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6/01 cJCIRC/DateDue.pGS-p.15

GROWTH STATUS AND PHYSICAL FITNESS OF PRIMARY
SCHOOL CHILDREN IN AN URBAN AND A RURAL COMMUNITY
IN OAXACA, SOUTHERN MEXICO

By

Maria Eugenia Peﬁa Reyes

A DISSERTATION

Submitted to
Michigan State University
in partial fulﬁllment of the requirements

for the degree of

DOCTOR OF PHILOSOPHY

Department of Kinesiology

2002

ABSTRACT

GROWTH STATUS AND PHYSICAL FITNESS OF PRIMARY SCHOOL
CHILDREN IN AN URBAN AND A RURAL COMMUNITY IN OAXACA,
SOUTHERN MEXICO

By

Maria Eugenia Peﬁa Reyes

This study considered the growth status and physical ﬁtness of primary school
children in a rural and an urban community in the Valley of Oaxaca, southern Mexico,
in 1999-2000. The prevalence of growth stunting, wasting, and overweight and obesity
were also considered. The sample included 700 school children 6 to 13 years of age,
361 from the rural community (177 males, 184 females) and 339 from the urban
community (173 males, 166 females). Anthropometric dimensions included body size,
segment lengths, skeletal breadths, limb circumferences and skinfolds. The body mass
index (BMI), leg length, arm and calf muscle circumferences, sum of skinfolds, and a
trunk/extremity skinfold ratio were derived. Physical ﬁtness items included motor-and-
health-related tests: right and left grip strength (muscular strength), 35 yard dash (32.3
meters, speed), standing long jump (explosive power), sit-and-reach (ﬂexibility), timed
sit-ups (30 seconds, abdominal strength and endurance), and a distance run (8 minutes
in grades 1-3 and 12 minutes in grades 4-6, cardiovascular endurance).

Height, weight, sitting height, estimated leg length and skeletal breadths on the
trunk were signiﬁcantly larger in urban than in rural school children. The BMI,
sitting height/stature ratio, skeletal breadths on the extremities, limb and estimated
limb muscle circumferences, subcutaneous fatness and relative fat distribution did

not consistently differ by age group and sex between urban and rural children.

Urban children tended to perform better in the sit and reach, sit-ups and
standing long jump, but results were not consistently signiﬁcant. Rural children 6-9
years tended to perform better in the dash. There were no urban-rural differences in
grip strength, but strength per unit body mass was greater in rural children. Rural
children in grades 1-3 performed better in the distance run, but results in older
children were not consistent.

The prevalence of stunting was about twice as great in rural than in urban
children, but the prevalence of wasting was very low in both communities. The
prevalence of overweight was signiﬁcantly greater in urban than in rural children, but
he prevalence of obesity was low.

Rural children, boys more than girls, reported more frequent daily
participation in household-related activities classiﬁed as moderate and moderate-to-
vigorous in intensity compared to urban children. Urban boys reported more
household-related activities of light or very light ntensity. Urban and rural girls did
not differ in reported frequencies of daily household activities classiﬁed of light and
very light intensity. Urban children reported more diversity in diet, speciﬁcally at
breakfast and dinner, than rural children. Animal protein represented in meats and
meat derivatives were rather limited in the diets of rural children.

The results of the comparisons of growth status, physical ﬁtness, daily
activities and diet of urban and rural primary school children reﬂect, to a large
extent, the contrast of living conditions and access to resources in the urban and rural

communities.

Copyright by
MARIA EUGENIA PENA REYES
2002

Dedication
To my mother and father whose faith in my dreams never declined

To my family, their energy and happiness help make sense of my life

ACKNOWLEDGMENTS

My ﬁrst words thank Dr. Robert M. Malina who has been the most inﬂuential
person on my professional career. The opportunity to work with him is not only an
academic experience but also a good example of how discipline for work and
enthusiasm could be combined with friendship towards success. My gratitude to the
students from the National School of Anthropology in México (ENAH ) Alma Garcia
Montes, David Lopez Romero, Marcos Ramirez Hernandez, Arturo Ramirez Ortiz,
Monica Franco Franco, Rafael Buenrostro, Margarita del Olmo, Denise Lambaer
Urrutia who participated in data collection. My recognition to local authorities, Mr.
Evaristo Lopez Lopez and Mr.Aurelio Mejia Santiago, teachers and to the school
children in the communities studied because their willingness to participate made this
work possible. My recognition to Swee K Tan for her work on the project. Thanks to
my committee members Dr. Manuel Chavez, Dr. James Pivarnik and Dr. Scott
Whiteford for their help and support along the process. To all my colleagues and
friends in Mexico and in United States whose support was a great companion. My
graduate studies and the completion of this dissertation was partially funded by The
National Institute of Anthropology in México (INAH), The University Graduate
Continuing Fellowship, Michigan State University, 1997, The National Science

Foundation grant BCS 9816400.

vi

Table of Contents

LIST OF TABLES ........................................................................................................... ix

LIST OF FIGURES ...................................................................................................... xiii

CHAPTER 1

INTRODUCTION ............................................................................................................. 1
Research Questions ............ . ..................................................................................... 7
Limitations ............................................................................................................... 7
Signiﬁcance .............................................................................................................. 8
Overview of Previous Studies in the Communities of Interest ............................ 9
Summary of Findings of Previous Studies ........................................................... 10

CHAPTER 2

REVIEW OF LITERATURE .......................................................................................... l3
Urban-Rural Contrasts — General Considerations ............................................... 13
Urbanization in Mexico ..................................................................... . ................... 18
Urbanization and Migration .................................................................................. 21
Migration and Demographic Characteristics of Oaxaca ..................................... 23
Urban-Rural Contrasts in Latin America and Speciﬁcally Mexico ................... 24
Functional Consequences of Undemutrition ....................................................... 32
Summary ................................................................................................................. 46

CHAPTER 3

METHODOLOGY .......................................................................................................... 47
Conditions in the Valley of Oaxaca ...................................................................... 48
The Communities ................................................................................................... 50
Overview of Conditions in the Rural and Urban Communities ......................... 60
Subjects .................................................................................................................. 61
Data Collection Procedures ................................................................................... 63
Statistical Analysis ................................................................................................ 74

CHAPTER 4

RESULTS ......................................................................................................................... 79
Anthropometry ....................................................................................................... 79

vii

Physical Fitness ..................................................................................................... 82

Stunting .................................................................................................................. 83
Wasting ................................................................................................................... 84
Overweight and Obesity ........................................................................................ 84
Activities of 4‘“, 5‘“ and 6th Grade Children ......................................................... 85
Dietary Information of 4‘“, 5th and 6th Grade Children ........................................ 88
CHAPTER 5
DISCUSSION .................................................................................................................. 91
Growth Status ......................................................................................................... 91
Overweight, Obesity and Wasting ........................................................................ 95
Stunting .................................................................................................................. 97
Physical Fitness, Physical Activity and Diet ....................................................... 98
Urban and Rural Life in Oaxaca - An Overview .............................................. 103
CHAPTER 6
SUMMARY AND CONCLUSIONS ............................................................................ 109
TABLES ................................................................. 117
FIGURES .............. 156
APPENDICES ............................................................................................................... 188
Appendix I. University Committee for Research Involving Human Subjects ...... 189
Appendix 11. Data Collection Forms .................................................................. 194
Appendix III. Tables of Descriptive Statistics ................................................... 201
BIBLIOGRAPHY ......................................................................................................... 216

viii

List of Tables

Table 1.1. Demographic, Economic, Education and Health Indicators for ...... 1 18
the State of Oaxaca relative to national statistics.

Table 2.1. Living conditions in the state of Oaxaca, 1980-2000. ........ 120

Table 2.2. Mean weight (kg) and height (cm) for urban (Durango) and rural ........ 121
(Morelos) children in Mexico in the 19603 by age group (years).

Table 2.3. Socioeconomic variation in the weight (kg) and height (cm) ........ 122
of urban boys in the Federal District and corresponding data for
low socioeconomic status rural boys from a community close to
the Federal District by age group (years).

Table 2.4. Socioeconomic variation in the weight (kg) and height (cm) of ........ 123
urban boys and girls in the Federal District by age group (years).

Table 2.5. Mean weight (kg) and height (cm) of indigenous Tojolabal ........ 124
children from Chiapas by age group (years).

Table 2.6. Mean height (cm) of a sample of indigenous Otomi children and ........ 125

a sample of urban middle class children by age group (years).

Table 3.1. Population distribution of Santo Tomas Mazaltepec by age group ........ 126
and sex in 2000.
Table 3.2. Indicators of social, economic, educational and health conditions ........ 127

in the rural and urban communities with comparative data for the city
of Oaxaca and the state of Oaxaca based on the national census for
2000.
Table 3.3. Numbers of school children surveyed in the rural and urban ........ 128
communities, 1999-2000, by age group and sex.
Table 3.4. Intra-observer technical errors of measurement for ........ 129

anthropometric dimensions.

Table 3.5. Within day reliabilities for physical ﬁtness items based in
intraclass correlations derived from repeated measures ANCOVA
with age as the covariate, sexes and rural and urban samples
combined.

Table 3.6. Within day reliabilities for physical ﬁtness items based on
correlations between trials, rural and urban samples combined.

Table 3.7. Sample sizes by age group and sex, and means and standard
deviations for chronological age for the rural and urban children
included in the analysis.

Table 3.8. Status quo menarcheal status of girls 9-15 years of age in the
rural and urban communities.

Table 4.1. Age-adjusted means and standard errors for indicators of body
size and proportions in rural and urban children 6-9 and 10-13 years
ofage.

Table 4.2. Age-adjusted means and standard errors for skeletal breadths
and limb circumferences in rural and urban children‘6—9 and 10-13
years of age.

Table 4.3. Age-adjusted means and standard errors for subcutaneous
fatness and relative subcutaneous fat distribution in rural and urban
children 6-9 and 10-13 years of age.

Table 4.4. Age-adjusted means and standard errors for indicators of muscular
strength in rural and urban children 6-9 and 10-13 years of age.

Table 4.5. Age-adjusted means and standard errors for indicators of
physical fitness in rural and urban children 6-9 and 10-13 years
of age.

Table 4.6. Prevalence [95% conﬁdence intervals] of stunting in rural and

urban children 6-13 years of age.

........ 130

........ 131

........ 132

........ 133

........ 134

........ 135

........ 136

........ 137

........ 138

........ 139

Table 4.7. Prevalence of wasting [95% conﬁdence intervals] in rural and
urban children 6-13 years of age based on the body mass index.

Table 4.8. Prevalence [95% conﬁdence intervals] of overweight and
obesity, using intematonal criteria, in rural and urban males 6-13
years of age based on the body mass index.

Table 4.9. Prevalence [95% conﬁdence intervals] of overweight and
obesity, using intematonal criteria, in rural and urban females 6-13
years of age based on the body mass index.

Table 4.10. Household activities reported by rural and urban school
children in 4‘“, 5‘“ and 6‘“ grades: Frequencies reported and
corresponding percentages.

Table 4.11. Recreational activities reported by rural and urban school
children in 4‘“, 5‘“ and 6‘“ grades: Frequencies reported and
corresponding percentages.

Table 4.12. Time spent viewing television (hours per day) reported by
rural and urban school children in 4‘“, 5‘“ and 6‘“ grades: Frequencies
reported and corresponding percentages.

Table 4.13. Frequency of household-related activities before and after

school by estimated level of intensity reported by rural and urban 4‘“,

5‘“ and 6‘“ grade school children.

Table 4.14. Recreational activities reported by rural and urban 4‘“, 5‘“ and
6‘“ grade children during the break period at schoole requencies and
corresponding percentages.

Table 4.15. The total number of foods reported and the ten foods reported
most often at breakfast (desaﬂno) by rural and urban children in the
4‘“, 5‘“ and 6‘“ grades - percentages reporting consumption of each

food item in the past 24 hours (sexes combined).

xi

........ 140

........ 141

........ 142

........ 143

........ 144

........ 145

........ 146

........ 147

........ 148

Table 4.16. The total number of foods reported and the ten foods reported

most often at lunch (comida) by rural and urban children in the 4‘“,

 

5‘“ and 6‘“ grades - percentages reporting consumption of each food
item in the past 24 hours (sexes combined).

Table 4.17. The total number of foods reported and the ten foods reported
most often at dinner (w) by rural and urban children in the 4‘“, 5‘“
and 6‘“ grades - percentages reporting consumption of each food item
in the past 24 hours (sexes combined).

Table 5.1. Age-adjusted means and standard errors based on ANCOVA
with age as the covariate for indicators of body size in urban school
children grouped by place of birth.

Table 5.2. Age-adjusted means and standard errors based on ANCOVA
with age as the covariate for indicators of body size in rural school
children grouped by place of birth.

Table 5.3. Estimated prevalence (%) of overweight and obesity in primary

school children 6 to 13 years of age from several areas of Mexico.

........ 149

........ 150

........ 151

........ 152

........ 153

Table 5.4. Estimated prevalence (%) of wasting in primary school children ........ 154

6 to 13 years of age from several areas of Mexico.
Table 5.5. Estimated prevalence (%) of growth stunting in primary school

children 6-13 years of age by age group in Oaxaca and Chihuahua.

xii

........ 155

List of Figures

Figure 3.1. Map of the Valley of Oaxaca indicating the location of the two

communities studied.

Figure 4.1. Mean height of urban and rural boys relative to selected
percentiles of United States reference data (Centers for Disease
Control and Promotion, 2000).

Figure 4.2. Mean height of urban and rural girls relative to selected
percentiles of United States reference data (Centers for Disease
Control and Promotion, 2000).

Figure 4.3. Mean weight of urban and rural boys relative to selected
percentiles of United States reference data (Centers for Disease
Control and Promotion, 2000).

Figure 4.4. Mean weight of urban and rura1 girls relative to selected
percentiles of United States reference data (Centers for Disease
Control and Promotion, 2000).

Figure 4.5. Mean body mass index of urban and rural boys relative to
selected percentiles of United States reference data (Centers for
Disease Control and Promotion, 2000).

Figure 4.6. Mean body mass index of urban and rural girls relative to
selected percentiles of United States reference data (Centers for
Disease Control and Promotion, 2000).

Figure 4.7. Mean height of urban and rural children.

Figure 4.8. Mean weght of urban and rural children.

Figure 4.9. Mean body mass index of urban and rural children.

Figure 4.10. Mean sitting height and estimated leg length of urban and

rural children.

xiii

........ 157

........ 158

........ 159

........ 160

........ 161

........ 162

........ 163

........ 164
........ 165
........ 166
........ 167

Figure 4.11. Mean sitting height/standing height ratio of urban and rural ........ 168

children.

Figure 4.12. Mean biacromial and bicristal breadths of urban and rural ........ 169
children.

Figure 4.13. Mean bicondylar and biepicondylar breadths of urban and ........ 170

rural children.
Figure 4.14. Mean arm and calf circumferences of urban and rural children. ........ 171
Figure 4.15. Mean estimated arm and calf muscle circumferences of urban ........ 172

and rural children.

Figure 4.16 Mean triceps skinfold thicknesses of urban and rural children. ........ 173‘

Figure 4.17. Mean subscapular skinfold thicknesses of urban and rural ........ 174
children.

Figure 4.18. Mean suprailiac skinfold thicknesses of urban and rural ........ 175
children.

Figure 4.19. Mean medial calf skinfold thicknesses of urban and rural ........ 176
children.

Figure 4.20. Mean sum of skinfold thicknesses of urban and rural children. ........ 177

Figure 4.21. Mean trunk/extremity skinfold ratios of urban and rural children. ........ 178

Figure 4.22. Mean right grip strength of urban and rural children. ........ 179

Figure 4.23. Mean left grip strength of urban and rural children. ........ 180

Figure 4.24. Mean sum of right and left grip of urban and rural children. ........ 181

Figure 4.25. Mean grip strength (sum of right and left) per unit body ........ 182

weight in urban and rural children.

Figure 4.26. Mean sit-and-reach of urban and rural children. ........ 183

Figure 4.27. Mean timed sit-ups in urban and rural children. ........ 184

Figure 4.28. Mean standing long jump performance of urban and rural ........ 185
children.

xiv

Figure 4.29. Mean 35-yard dash performance of urban and rural children. ........ 186
Figure 4.30. Mean distance run in 8 minutes (grades 1-3) and in 12 minutes

(grades 4-6) by urban and rural children. ........ 187

XV

Chapter 1

Introduction

The present study is developed within the context of quality of life and health
related outcomes in two communities of the state of Oaxaca, in southern Mexico. It
focuses on an aspect of a broader study designed with the purpose of evaluating secular
changes in growth status, physical ﬁtness, and living conditions in two communities in
the Valley of Oaxaca, which were initially studied in 1968 and 1972 and again in 1999-
2000 (Malina et al., 1972, 1980a; Malina and Selby 1982; Malina, 1999).

Deﬁcits in nutrition and a high prevalence of infectious and parasitic diseases
are major stresses that characterize the long term living conditions of the populations
of interest. The growth status of children is highly sensitive to the quality of life in a
community and particularly to marginal nutritional conditions. The main focus of the
overall study is secular change (Malina, 1999). Positive secular changes in height
during childhood and in adulthood are indicative of improved nutritional, health and
socioeconomic circumstances, all of which are interrelated. The present study
concentrates on urban-rura1 comparisons of growth and physical ﬁtness as related to
contrasting living conditions in the two communities.

Historically, Mexico has experienced uneven regional development, largely
inﬂuenced by inequitable distribution of resources among areas. This is reﬂected in the
economy as a whole and on living conditions for the population. The ongoing
transformation, beginning in the 19508, was intended to integrate rural areas into the
market economy of the nation. The main strategies included construction of new roads
and establishment of an irrigation infrastructure to make rural communities more
accessible. Several years later, the strategy shifted to the development of urban areas

and industrial parks whose objective was to attract the population into productive roles

and in turn, encourage economic growth. At the same time, other programs attempted
to enhance rural development (Palma-Cabrera, 1993). The cases for Oaxaca and several
other states (Chiapas and Guerrero) are somewhat singular because these states did not
seemingly beneﬁt from the progress experienced by the other states of Mexico.

Agricultural policies that characterized the land reform of the Cardenas
administration (1934-1940) contributed to the emergence of a large number of small
land owners under the gig; system (i.e., collectively owned land). The owners of
these small holdings had to deal with a lack of resources and general poor land quality,
associated with erosion over time and single crop cultivation. These in turn placed
consistent demographic pressures on the lands and affected productivity. The
conditions in Oaxaca were further exacerbated by the local geography (i.e.,
mountainous terrain), limited construction of roads and thus access to markets, and
lack of basic infrastructure for electricity, potable water, education and public health.
These factors had their greatest impact on small, rural communities which dominate
the state of Oaxaca. Further, by shifting national emphasis from agriculture to
industry, capital investments tended to be concentrated in the southern areas of the
state of Oaxaca. These include Tuxtepec and the Isthmus, areas which were oriented
towards exchange with the states of Veracruz and Puebla instead of the capital, Oaxaca
de Juarez and other communities the Valley of Oaxaca. The net result was reduced
sources of work opportunities and in turn income for the local population, which
contributed to the marginalization of living conditions for the more traditional, largely
indigenous, rural communities. The prevalence of poverty increased and it was
associated with illiteracy, high fertility and high infant and preschool mortality
compared to more developed regions of the country (Arellanes, 1988; Gonzalez-Garcia
and Monterrubio-Gomez, 1993).

Living conditions as assessed by the health and nutritional status of children and

adults provide useful information to estimate the impact of social and environmental

factors on the quality of life of members in a given community. The state of Oaxaca
has gone through signiﬁcant agricultural transformation in the past three decades,
although the outcomes are not as positive in terms of economic growth as they have
been for northeastern states such as Sinaloa, Sonora, or Baja California. The critical
transformation in the agricultural sector, following inclusion of the country in the open
market economy, brought serious challenges for local economies to maintain food
availability in light of increasing costs associated with buying rather than producing
foods to meet basic human needs.

Small scale farmers and landless agricultural workers in regions where
technological change has taken place are at greater risk for limited access to food
(Dewey, 1985; Diskin, 1991; Enge and Martinez-Enge, 1991; Food and Agriculture
Organization (FAO), 1996; Stonich, 1993; Whiteford and Ferguson, 1991). Farmers
who do not have access to the resources needed to acquire technology, primarily for
irrigation, are relatively worse-off. Adoption of new technology affects intra-
household allocation of labor for production and processing activities. In a parallel
manner, women have been forced to work in agricultural production, but without being
paid at the same rate as male wage laborers. This trend has the added disadvantage for
intra-family needs and relationships, which require the efforts of women for family
subsistence at the household level (Mebrahtu et al., 1995).

Although signiﬁcant changes have occurred in the state of Oaxaca over the past
three decades, the state still lags behind other states of Mexico in social, economic and
health indicators. Several trends in demographic, economic, education and health
indicators for 1999 and 2000 are summarized in Table 1.1. Among other states of
Mexico, Oaxaca has the lowest growth rate, due in part to a relatively high rate of out-
migration. The state of Oaxaca is unique among Mexican states in that 55% of its
localities (municipios) have <2500 inhabitants, which is the highest percentage in the

country. These munigipios are located in rural areas. The state of Oaxaca also ranks

among the highest in the percentage of its population <15 years of age (38%) and 265
years of age (6%), but overall the state has a relatively young median age (20 years).

From an economic perspective, the state of Oaxaca ranks lowest in the country
(32“) in GDP per capita, but in midstream for GDP as a fraction of the total GDP for
Mexico (1.5%, 19‘“). The minimum wage is also slightly lower in Oaxaca compared to
the national estimate.

The state of Oaxaca also ranks high in illiteracy and the percentage of
individuals with an incomplete primary school education, 3"d and 2“d in the country,
respectively, and low in the percentage of population with post-primary school
education, 31“.

The demographic, economic and education ﬁgures are consistent with marginal
status of the state of Oaxaca for health-related indicators. The state of Oaxaca ranks
among the highest in Mexico for overall death rate and deaths from intestinal and
respiratory infections. On the other hand, the state ranks among the lowest (30‘“) in
physicians per 10,000 population. The state of Oaxaca has a relatively high birth rate
among Mexican states, and an estimated infant mortality rate that is relatively low
(1 1 . 1/ 1000 live born). This is somewhat puzzling given the high prevalence of
intestinal and respiratory infections in the state. However, infant mortality for the state
of Oaxaca and other largely rural states in Mexico must be tempered with caution.
These states have a history of a high rate of underreporting birth and infant mortality
statistics (Cordero, 1968; Aguirre and Camposortega, 1980; Canales et al., 1980).

Overall, the demographic, economic, education and health indicators suggest
marginal conditions in the state of Oaxaca compared to the country of Mexico as a
whole. The conditions are exacerbated by the high percentage of the population living
in small, rural communities, and high mortality from intestinal and respiratory
infections. The low GDP per capita for Oaxaca reﬂects in part the inequitable

distribution of economic resources in the country and within the state. These

conditions are the substrate within which children grow and mature, and the growth
status of children is commonly viewed as reﬂecting the health and nutritional
conditions in a society (World Health Organization, 1995, see below).

The growth status of children in developing countries, based primarily on
anthropometric indicators such as weight, height, weight-for-age, height-for—age and
weight-for—height, is accepted as an indicator of the overall health and nutritional status
of a community (World Health Organization, 1995). Health is. .. “a human condition
with physical, social and psychological dimensions, each characterized on a continuum
from positive to negative poles. The positive health is associated with a capacity to
enjoy life and to withstand challenges not only absence of disease, the negative health
is associated with morbidity and taken to the extreme with premature mortality”...
(Bouchard et al., 1997, p. 99). Primary concern with unfavorable living conditions,
particularly chronic mild-to-moderate undemutrition among children in many
developing countries of the world, is related to potential long-term functional .
consequences that may jeopardize adult health and ability to earn an adequate daily
living (Pollitt et al., 1996).

Although emphasis is placed on growth status as an indicator of health and
nutritional conditions in a society (Bielicki, 1986, 1999), there is increasing interest on
overweight in some developing countries (Popkin et al., 1996). The estimated
prevalence of overweight (deﬁned as weight-for-height more than two standard
deviations above international reference medians) among children under ﬁve years of
age in developing countries range from about 5% in Latin America and the Caribbean
to 3% in Africa and 2% in Southeast Asia (World Health Organization, 1995; de Onis
and Blossner, 1997, 2000). There is, however, variation among and within countries.
Better developed countries within a geographic region and more afﬂuent sectors of
society within a country have a higher prevalence of overweight. In general, as the

prevalence of overweight increases, the prevalence of wasting (deﬁned as weight-for-

height more than two standard deviations below the international reference) within a
country decreases. However, both overweight and wasting of preschool children are
common in many countries. Stunting (deﬁned as height-for—age more than two
standard deviations below the international reference) is an additional nutritional
concern in many developing countries. Growth in height reﬂects, to a large extent, the
individual’s nutritional history, and stunting is attributed to chronically poor or
marginal nutritional circumstances during the preschool years. This suggests an
epidemiological paradox — persistent undemutrition (wasting and stunting) in the
presence of increasing overweight as countries go through an economic and nutrition
transition (Popkin et al., 1996).

The prevalence of overweight and/or obesity has increased among urban school
children in Mexico (Rangel et al., 1993; Siegel, 1999; Pefia Reyes et al., 2002).
Corresponding information for school children in rural areas and in rapidly growing
urban slums (see below) are not presently available. Issues related to overweight and
obesity among children from rural and marginal urban circumstances in developing
countries has received relatively little attention because the prevalence of chronic
undemutrition is still a major concern due to the relatively large proportion of
children affected.

Major cities in Latin American have experienced rapid growth associated with
rural to urban migration. In Mexico, for example, at the beginning of the 20‘“ century
only 10% of the total population lived in urban areas whereas the remaining 90%
lived in widely distributed rural communities of <15,000 inhabitants. Subsequently,
a shift in population occurred, at ﬁrst gradually and then more rapidly, so that by
1990 approximately 58% of the population lived in urban areas (about 46,700,000
inhabitants) and 42% lived in rural areas (34,500,000 inhabitants), including many
small communities. Living conditions in urban and rural settings are often markedly

contrasting in the context of access to health services, quality of schools, unstable

food supplies, and so on. The present study is set in the context of urban-rural

contrasts.

Research Questions
The present study is set within the context of three questions:

1. How do current samples of urban and rural school children 6-13 years of age in
Oaxaca, southern Mexico, compare in growth status?

2. How do current samples of urban and rural school children 6-13 years of age in
Oaxaca, southern Mexico, compare in physical ﬁtness?

3. How do current samples of urban and rural school children 6-13 years of age in
Oaxaca compare in the estimated prevalence of growth stunting and wasting?

4. How do current samples of urban and rural school children 6-13 years of age in '
Oaxaca compare in the estimated prevalence of overweight and obesity?
The following hypotheses will be tested:

1. Urban school children have better growth status assessed with height, weight
and other anthropometric indicators than rural school children.

2. Urban school children perform better on tests of physical ﬁtness than rural
school children.

3. Rural school children have a higher prevalence of growth stunting and wasting
than urban school children.

4. Urban school children have a higher prevalence of overweight and obesity than

rural school children.

Limitations
The study is based on cross-sectional surveys of two communities in the Valley
of Oaxaca, one a rural indigenous community where the Zapotec language is spoken,

and the other an urban colonia, which is now subsumed in the capital city of Oaxaca

 

(Oaxaca de Juarez). The Valley of Oaxaca is intermontane and includes many rural
populations. However, the urban population is rapidly growing. Rural communities
are characterized by relatively little or slow development, lack of adequate public
utilities and health services, associated poverty, marginal agricultural productivity, and
often relatively poor agricultural land. On the other hand, the urban settlements,
largely on the perimeters of major cities, have developed as a consequence of
consistent migration from rural villages. The process of migration observed in areas
such as Oaxaca shows that migrants congregate in irregular settlements located at the
periphery of cities, resulting in what are called “colonias pgpulares.” Health and
nutrition conditions associated with migration to cities are generally poor in these
marginal areas (Selby and Murphy, 1979; Murphy et al., 1991).

The two communities in the present study were studied initially about 30 years
ago. The rural, gimme-speaking community was studied in 1968 and then again in
1978 and 1979 (Malina et al., 1972; 1980a; Buschang, 1980). The urban community
was studied initially in 1972, when the growth status of school children in several -
urban and rural communities was surveyed (Malina et al., 1976, 1980b). The present
study did not attempt to locate members of the communities who participated in the
earlier surveys because the demographic dynamics of the communities are
characterized by a relatively high rate of out-migration. This would make it difﬁcult to
trace families and individuals who participated in the earlier surveys (see Malina et

aL,1982)

Significance

Living conditions in the urban colonia and the rural Zapotec-speaking

 

community are reasonably typical of corresponding communities in the Valley of
Oaxaca. Based on earlier studies in Oaxaca (Malina et al., 1981; Malina, 1983) and a

recent national survey of primary school children including samples in Oaxaca

(Instituto Nacional de Salud Publica, 2000), it is reasonable to assume that the
children from the two communities are representative of public primary school
children in other communities in the Valley of Oaxaca. They are probably different
from children of the same age who are from economically better-off families and
attend private schools in the city of Oaxaca.

The growth status of children is a valuable, direct indicator of the health and
nutritional conditions of communities in developing countries. The results will reﬂect
rural-urban contrasts in overall quality of life.

Chronic mild-to-moderate undemutrition is a risk factor for several functional
impairments. However, there is at present limited information for Mexico that
assesses this relationship, apart from earlier studies by Malina and colleagues. Other
available data from Mexico focus more often on the relationship between severe
protein-energy undernturition early in life and functional status in preschool children.
This is well documented in the work of Chavez and Martinez (1984) and Cravioto
(1980, see also Cravioto and Arrieta, 1986). Compared to preschool children, school
age children are unique in many parts of Mexico and other developing countries.
They represent the survivors of a rigorous selection process that involves chronic
undemutrition and infectious diseases, and associated morbidity and mortality. 'School

children will be, to a large extent, the next generation of economically active adults.

Overview of Previous Studies in the Communities of Interest

Previous studies conducted by Malina and colleagues in the Valley of Oaxaca
began in 1968 in Santo Tomas Mazaltepec, a on_teg-speaking community of about
1250 individuals in the mid-19603. The initial study focused on the growth status of
the primary school children, 6-14 years, and foods consumed at the household level
in a single rural community. In 1971 and 1972 the study expanded to include

primary school children in several contrasting communities in the Valley of Oaxaca,

including an additional Zapotec-speaking community (Magdalena Teitipac), two

urban colonias (Benito Juarez, San Juan Chapultepec), and two rura1 Ladino

 

communities (Rojas Cuauhtemoc, San Francisco Telixtlahuaca). The combined
sample from 1968 to 1972 was approximately 1450 primary school children (Malina
etaL,1980b)

A ten-year follow-up of Santo Tomas Mazaltepec was undertaken in 1978
(Malina et al., 1980a, Malina and Selby, 1982). The study included a village census
(approximately 1700 inhabitants), and the growth status and motor ﬁtness of school
children 6-14 years of age. The study also included food items consumed at the
household level, status quo and retrospective menarcheal data, and anthropometry of
adults. In 1979 a one-year follow-up of the school children was undertaken to estimate

velocity of growth (Buschang, 1980).

Summary of Findings of Previous Studies

Growth status in the combined sample from 1968 to 1972 included 1450
children 6-16 years of age from two rural Zapotec-speaking communities, two rural
Ladino communities and two colonias populares= Mean statures were consistently
below the 5‘“ percentile of US. (NCHS) reference values. A delay in the adolescent
spurt was suggested by the deviation of stature below the 5‘“ percentiles after 11-12
years. Body weights of girls, on average, fell between the 5‘“ and 10‘“ percentiles
whereas those of boys were close to the 5‘“ percentile from 6-11 years and fell below
the 5‘“ percentile subsequently (Malina, 1982, 1983). Weight-for-stature in boys and
girls, on the other hand, corresponded to medians for prepubertal US. children
(NCHS). Although they are absolute shorter and lighter, the school children of
Oaxaca have appropriate weight—for—stature.

In a more speciﬁc study of the mtg-speaking community (STM) in 1978, the

school children were grouped on the basis of an economic index derived from

10

landholdings, household goods and occupation. Within this seemingly single class
rural community boys from higher socioeconomic status (SES) households had better
growth status. The same trend was evident for girls, but the results were not
signiﬁcant (Malina et al., 1985). Evidence of early growth deﬁcits was suggested in
the estimated growth velocities based on 1978 and 1979 surveys. Estimated velocities
of growth in height did not differ between children from high and low SES
households (Little et al., 1988). Growth rates of school children from STM, including
body weight, stature, sitting height and estimated leg length, when compared to
corresponding data for well nourished children of similar age, also suggested that the
growth deﬁcits affecting stature and estimated leg length in Law children occurred
during early childhood (Buschang, 1980; Buschang and Malina, 1983; Buschang et
al., 1986).

The growth of Oaxaca children was compared to middle class children of
Mexico City (Ramos Galvan and Luna Jaspe, 1964), to reference values for well-off
Mexico City children (Ramos Galvan, 1975), and to children from low economic
conditions (Perez Hidalgo et al., 1965). Children from Oaxaca tended to be even
smaller than the children from poor socioeconomic conditions (Malina et al., 1972;
Malina, 1982, 1983).

The rural-urban comparison of Oaxaca school children showed that the rural
Quote; children were smaller than rural Ladino and urban gm children. The
rural m children also had smaller estimated mid-arm muscle circumferences

than both rural Ladino and urban colonia children (Malina et al., 1980b).

 

Children from the rural Epic; community also had lower absolute levels of
strength and motor ﬁtness compared to well-nourished children of the same age and
sex. However, per unit body size, grip strength was appropriate, running and jumping
performances were less, and throwing performance was better than expected (Malina

and Buschang, 1985; Malina et al., 1987).

11

There was no secular change in stature, weight, arm and estimated mid-arm
muscle circumferences, the triceps skinfold, and grip strength of school children in
Santo Tomas Mazaltepec over the 10-year interval between 1968 and 1978 (Malina et
al., 1980a). Diet estimated from the foods consumed at the household level also
indicated little change between 1968 and 1978 (Pefia et al., 1995). The lack of secular
trend change over the short term (1968-1978) appeared consistent with lack of secular
change in height among m adults between 1899 and thel97OS (Malina et al.,
1983). In this context, it was concluded that more time was perhaps needed before
improvements in indicators of public health, such as easier access to health care and a
decline in infant mortality, among others, may be reﬂected in improved growth status
of school children (Malina and Selby, 1982).

The present study is concerned with urban-rural contrasts in growth and
physical ﬁtness, and in the prevalence of stunting, wasting and overweight/obesity.
Data collected for the present study provide the basis for a more comprehensive
comparison of changes in growth status between 1968/1978 and 2000, which is the
major focus of the broader study (Malina, 1999). The analysis of secular change in
the growth status of school children indicates a major increase in height
(approximately 6 cm) over the past 30 years or so. Since there was no short term
secular change between 1968 and 1978, the major increase in height has thus occurred
over the past 20 years (Malina, 2002). Consistent with the secular change literature
(Bielicki, 1986, 1999), the improved growth status of the primary school children in

Oaxaca can be viewed as reﬂecting improved health and nutritional conditions.

12

Chapter 2

Review of Literature

The present study is concerned with urban-rural contrasts in growth and physical
ﬁtness, and in the prevalence of stunting, wasting and overweight/obesity of school
children in the Valley of Oaxaca in southern Mexico. The review ﬁrst considers presently
available comparisons of the grth status and physical ﬁtness of urban and rural
children in different parts of the world. It then focuses on urbanization in Mexico and
related issues, and then more speciﬁcally on the demographic characteristics of the
population in the state of Oaxaca, including recent trends in migration. Urban-rural
contrasts in the grth status of Latin American children and speciﬁcally those in
Mexico are then considered. Finally, the functional consequences of chronic

undemutrition, including effects on motor performance and physical ﬁtness are reviewed.

Urban-Rural Contrasts — General Considerations

The signiﬁcant changes that accompany the transition from agricultural to urban
industrial societies have greatly impacted the social and biological transformation of
populations worldwide. The urbanization process, however, occurs under different
circumstances among countries. In the case of Europe, for example, urbanization has
been a long term process, directed largely by individual interests and needs. In contrast,
the process of urbanization in most developing countries of the world has been dictated

by worldwide economic demands and constraints (Valladares and Coelho, 1993).

Living Conditions

Urbanization in Europe was characterized by consistent improvements in the

economy which clearly favored nutrition and child care. The favorable conditions

13

associated with urbanization in Europe included a regular supply of goods and
services, and relatively easy access to health care and related service institutions
(Tanner and Eveleth, 1976). Children in the cities beneﬁted from sanitation and health
services, large medical institutions, and educational, recreational and welfare
facilities. In contrast, rural dwellers generally did not have equivalent services, and
even worse, often lacked food during critical periods of growth. Other problems in
rural areas which impacted the nutritional and health status of children were related to
lack of adequate food storage facilities and inequitable distribution of resources. In
addition to environmental differences, a more diverse genetic background probably
resulted from migration and subsequent admixture in urban settings. This genetic
heterogeneity may be an additional factor, which inﬂuences growth status.

Accelerated urbanization in developing countries at present has reduced the
time that is needed to adjust to changes and, therefore, has affected not only lifestyle
but also the local ecology, often with serious consequences for health. Urbanization
has taken different paths depending on demographic proﬁle, health status, natural

resources and economic conditions, among many other factors (Schell et al., 1993).

Urban-Rural Contrasts in Growth

Data from Europe that span the past 100 years or so consistently indicate that,
within a speciﬁc country or cultural group, children in urban areas have greater size
and mature earlier than their peers in rural areas. In many countries, the urban-rural

differences persist in studies of adults (Bielicki, 1986). The differences in size
and maturity among children and adolescents in urban and rural areas are often
attributed to beneﬁcial changes in public health and nutrition and in general living
conditions associated with urbanization.

Meredith (1979, 1982) has reported comprehensive reviews of studies of

selected somatic characteristics of children and adolescents living in urban and rural

14

areas in various parts of the world. Data for the period from 1870 to 1915 showed
that children and youth of European ancestry residing in urban centers were generally
shorter and lighter than rural children. In contrast, data for the period 1950 to 1980
indicated that urban children were taller and heavier than rural children (Meredith,
1979, 1982). Data for the period between 1915 and 1950 are not as extensive but it
appeared that by the 1930s in Europe and the United States, the rural-urban contrast
was reduced and/or reversed (Malina et al., 1981).

At present, there are no signiﬁcant urban-rural differences in the growth status
of children and adolescents in the United States, Canada and most western European
countries (Hamill et al., 1972; van Wieringen et al., 1971; Eveleth and Tanner, 1976,
1990). On the other hand, some European countries, especially in eastern Europe
(e.g., Poland, Romania) and the Mediterranean area (e. g., Greece) continue to show
an urban-rural gradient in growth and maturity (Bielicki, 1986). Studies of 19 year
old Polish conscripts best illustrate the urban-rural differences because they account
for factors, which may potentially confound the comparisons. Among young adult
male conscripts surveyed in 1986, heights of those from rural areas were about 173
cm compared to 177 cm for those in larger urban centers, respectively (Bielicki et al.,
1992; see also Bielicki and Waliszko, 1991). Corresponding mean heights in 1995
were about 174 cm for conscripts from rural areas compared to about 179 cm for
conscripts from large cities (Bielicki et al., 1997). The trends for Polish conscripts
suggest that the urban-rural contrast in young adult height has not changed over time
from 1965 to 1995. Rural Polish girls also attain menarche later than urban girls,
although the difference between mean ages has declined from about 1.0 year to 0.6
year in surveys between 1955 and 1988 (Hulanicka and Waliszko, 1991).

Urban-rural contrasts are also evident among Han children and adolescents in
China (Han are the dominant ethnic group in China). Differences between mean

heights of urban and rural Chinese boys 7-18 years range from 2.9 to 5.7 cm;

15

corresponding differences for urban and rural girls range from 2.1 to 5.6 cm (Lin et al.,
19923). The urban-rura1 contrast is also reﬂected in later ages at menarche in rural
girls (Lin et al., 1992b). Similar urban-rural contrasts are evident in the growth and
maturity status of children and adolescents in parts of Africa (Spurgeon et al., 1984;
Cameron et al., 1992; Pawloski, 2002).

Urban-rura1 differences in growth and maturation reﬂect to a large extent the
inequitable distribution of and access to resources within a country. These include
economic, educational, nutritional and health-related resources. Such resources are
often concentrated in urban centers and are limited in the extent to which they ﬁlter

into the rural areas of some countries.

Urban-Rural Contrasts in Physical Fitness

In contrast to available data on comparisons of the growth and maturity status of
urban and rural children, corresponding data are limited for comparisons of physical
ﬁtness. Studies from the 19603 and 19703 indicate negligible differences in the physical
ﬁtness of urban and rural children in several European countries (Shephard, 1978).
Studies of Polish youth 7-15 years of age in the 19603 and 19703, in contrast, indicate
consistent urban-rura1 differences in tests of motor ﬁtness — vertical jump, medicine ball
throw for distance, dash, agility (Miemik, 1965; Pilicz and Sadowska, 1973). The
differences in motor ﬁtness may reﬂect the contrasting lifestyles of rural and urban
populations in Poland in the 19603 and 19703 because size differences (height and
weight) between the samples compared were rather small (Pilicz and Sadowska, 1973).
The same may explain variation in aerobic ﬁtness between youth 12-15 years of age
resident in alpine villages and midland urban centers in Switzerland (Buchberger, 1979).

Among Japanese primary school children 4—5 years of age, children residing in an
island community were more ﬂexible and had better motor coordination than urban

children, but the latter performed better in tests of motor ability — standing long jump,

16

ball throw, agility, dash (Munetaka et al., 1971). Data for Japanese elementary school
children and adolescents are variable (Tamura, 1975). Rural adolescents of both sexes
tend to have higher levels of aerobic power (ml/kg/min) and the urban-rural difference
increases with age. On the other hand, corresponding urban-rura1 contrasts for motor
performances vary among prefectures in Japan, but in many instances urban children
showed higher levels of motor ability. The rural-urban difference in endurance was
attributed to the fact that the rural children walked relatively long distances to school
and spent more time in physical activity (Tamura, 1975). This is consistent with the
positive association between indicators of physical activity and energy expenditure and
measures of cardiovascular endurance. On the other hand, the proﬁciency in motor
ability among urban children was attributed to better access to school physical
education and sport programs.

It is of interest that urban-rural comparisons of indicators of physical ﬁtness has
not received much attention in the auxology and‘sport science literature in the 19803
and 19903. This is perhaps due to the reduction of differences in lifestyle and in access
to health resources in urban and rural areas associated with economic development
during this time. Urban-rural comparisons of the performance of contemporary
American children are not available. A comparison early in the 20‘“ century indicated
negligible differences in lung capacity, grip strength and speed of limb movement
between urban and rural children in Missouri (Pyle, 1920).

Urban-rural comparisons in developing areas of the world are of limited
utility due to the generally marked socioeconomic and nutritional contrasts
between communities (Malina, 1990). Nevertheless, results in some studies are
variable. For example, rural children in South Africa of low socioeconomic status
tend to have lower grip strength compared to urban children of high socioeconomic
status, which probably reﬂects, to some extent, the reduced body size of the rural

children. In contrast, comparisons of neuromuscular reaction time and pulse rate

17

before and after exercise show no consistent rural-urban differences (Henneberg

and Louw, 1998).

Urbanization in Mexico

By the beginning of the 20th century in Mexico, it was estimated that only 10%
of the total population lived in urban areas. The other 90% lived in rural areas
comprising widely distributed in towns of less than 15,000 inhabitants. By the year
1990, about 58% of the population lived in urban areas (46.7 million inhabitants) and
the remaining 42% were in rural areas (34.5million inhabitants), including many in
small communities. Thus a major shift in the population distribution has occurred. A
rather large sector of the population was displaced from rural to urban settings.

The change in the population distribution in Mexico during the 20‘“ century had
several trends. Early in the century, the state with the most population was Jalisco,
followed by Guanajuato, Puebla, Veracruz and Oaxaca. In contrast, the state of Mexico
was 6‘“ and Mexico City was 10‘“ in population size. Between the 19803 and 19903,
there was a complete change in order and distribution of the population. The state of
Mexico, which surrounds the Federal District (Mexico City), is now the most highly
populated state in the country, approaching 10 million inhabitants, and the Federal
District (Mexico City) is now in second position. Guanajuato and Oaxaca moved down
in rank to the 6‘“ and 10‘“ positions, respectively (Cabrera-Acevedo, 1993).

Economic policies and structural changes contributed to better living
conditions, which in turn inﬂuenced demographic changes. The internal gross
national product doubled between the end of the 19403 and the beginning of the
19703. Improvements in living conditions and increases in social investments,
education and health were considered a social priority. Nevertheless, social
inequalities were prevalent and persisted. Disparities between social groups as

reﬂected, for example, in average mortality rates, varied to the extent that the

18

difference in life expectancy between extreme social groups was about 12 to 15 years
(Cabrera-Acevedo, 1993).

The economic goals for the country by the 19703 relied on industrialization with
corresponding impacts on population mobility and geographic distribution. Migration
from rural to urban areas, primarily to Mexico City, was dramatic. Mexico City
absorbed 50% of the total migration from different states, whereas the northern cities of
Guadalajara and Monterrey received another 10%. Baja California, in the northwest of
the country, was an important point for out-migration given its proximity to the United
States (Cabrera-Acevedo, 1993).

Agricultural reforms between 1934 and 1940 beneﬁted a large sector of the rural
population of Mexico. Agricultural modernization and irrigation were part of the so-
called “green revolution,” which had major results in the north of the country, whereas
the opposite was the case for the economy in the center and south of the country. From
the mid-19403 through the 19503, agriculture was adequate for food production and
economic resources (money stock) for the growing urban and industrial economy.

The industrial sector experienced a rapid growth from the 19403 to the19703,
which eventually proved to be the main inﬂuence for participation in work-related
activities in urban areas and in turn urbanization of the population. Industries were
located in the major cities, Mexico City, Monterrey, Puebla and Guadalajara. Private
and government investments stimulated the development of the basic infrastructure for
support of the oil, electricity, steel and iron industries, and in turn growth of the labor
force. Government support for industrialization also included commercial policies,
which included protective tariffs and import permits, that assured a protected market
for local industries in addition to tax exemptions and subsidized credits to promote
investment. The labor force experienced a considerable increase in that segment of the
population between 15 and 64 years of age, and a growing participation of women in

the work force.

19

Within the decade of 1930 to 1940, under the government of Lazaro Cardenas,
there was a signiﬁcant agricultural reform along with industrialization, which together
with demographic growth promoted better living conditions (well-being), increased
birth rates, and decreased mortality rates resulting in population growth. Increased
population mobility became a clearly recognizable social phenomenon, and was a key
factor in the increase in population size in the federal capital and surrounding urban
area (labeled Mexico City). It became the main destination for migrants from other
geographic areas of the country. As a result of this demographic growth, social,
economic and political problems emerged in rapidly expanding cities.

Social policies also played an important role in urban growth, among them being
investments in basic services such as education, sanitation and transportation. The
social security system (Instituto Mexicano del Seguro Social, IMSS) was implemented
in 1943, and by 1970, about one-fourth of the population was covered, although
beneﬁts were limited largely to urban areas.

On the other hand, government policies directed towards legalization of irregular
settlements on the periphery of large cities, i.e., colonias pgpulares, had the purpose of
meeting the housing needs of the rapidly growing urban population. Subsidies for
basic products, including energy, were largely directed towards regulation of the
national food supply. Most strategies had an urban bias, and, to a large extent,
beneﬁted the low-income sector of the urban population (Alba, 1993).

This accelerated economic development and demographic grth eventually
came to an end by the late 19703 when social policies (i.e., birth control, public health,
education, etc.) changed. Although the “green revolution” provided food self-
sufﬁciency to the country by the late 19703, agricultural production stopped growing.
Education made rather impressive advances, but the large numbers of illiterate
individuals did not decrease. Accumulation of human capital was also slowing, and the

labor force had, on average, only four years of education. Many did not complete six

20

years of primary school. Therefore, employment expectations of both the rural and
urban sectors became uncertain, and at this point, the advantages of urbanization were
seriously questioned (Alba, 1993).

In the context of changing conditions, the Consejo Nacional de Poblacion (1998)
developed an index of marginalization (indice de marginacion) to quantify inequities
within the country. Marginalization was deﬁned as persistent inequities that prevent
individuals and communities from enjoying progress and associated beneﬁts. The
index includes four components: (1) Education - percentage of literacy in the
population 15 years of age and older; percentage of people who did not complete
elementary school; (2) Housing — percentage of households without drainage and
electricity; percentage of people living in crowded households, household without
potable water, and houses with dirt ﬂoors; (3) Population distribution — populations
living in localities less than 5000 inhabitants; and (4) Income -— percentage of working
age individuals earning up to two minimum wages. Indices were estimated for the
municipal level using the 1990 census as a base and then a population update based on
the 1995 Conteo de Poblacion. The index for the state of Oaxaca was 1.85 (very high
marginalization). Indices for other states were 0.80 for Yucatan (high marginalization),
0.00 for Durango (medium marginalization), -0.85 for Sonora (low marginalization, - ,
1.27 for Baja California Norte (very low marginalization) and -1.74 for the Federal
District (very low). Most of the municipios in the state of Oaxaca were classiﬁed as

having a very high index of marginalization (Consejo Nacional de Poblacion, 1998).

Urbanization and Migration

Ecological changes and in some cases deterioration brought about by intensive
farming, crop failures, and limited assets contributed to rising debts, food insecurity and
reduction in good farm land, which were primary contributing economic factors

underlying rural to urban migration. An important question was, “What degree of food

21

deprivation is needed to trigger out-migration?” Failure of economic policies to stop
poverty is characteristic of agricultural modernization. It limits work opportunities by
offering low wages and growing underemployment in the form of informal activities.
These factors underlie out-migration from rural indigenous communities (Wilson, 1993).

Impoverished living conditions resulting from uneven regional development in
rural economies are among the main reasons behind migration in search of improved
family income. According to community-based observations, people with more years of
education have limited opportunities for jobs in the region. Young adults, particularly in
the age range 20 to 34 years, are the workers who most often seek jobs outside of their
respective communities. The type and duration of migration varies through time. Until
1950, indigenous migration was limited to temporary agricultural work in relatively close
geographical areas (Molina, 1991). The work generally involved cash-crops, such as
coffee and sugar cane, which required heavy physical work. After the work season, the
workers usually returned to their communities to carry on farming of their own lands and
the social and religious traditions of their respective communities. After 1960, however,
temporal farming production was no longer adequate to meet community needs, and
working outside of the community gradually became a prolonged absence and often
permanent migration involving the whole family.

The progressive detrimental impact of migration on a community takes different
forms which start with reduced participation in the local economy for a short period
and eventually leads to a demographic impact on the community by reducing the
number of economically active adults. In many cases, migration of young adult males
demands a reorganization of farming strategies as the work now has to be carried on by
women, children and older individuals. Associated changes are an increase in
supplementary income generating activities, such as handcrafts, hunting and ﬁshing.

There are thus two faces of migration. One is positive by providing economic

input to the community by sending funds to support small-scale agricultural

22

production that beneﬁts the local economy. The negative side is the occupational
mobility that often breaks-up family structures. It becomes more severe when
migration is long term and when women, children and older people must undertake

the essential subsistence agricultural labor tasks.

Migration and Demographic Characteristics of Oaxaca

The state of Oaxaca is characterized by high overall marginalization,
economically, socially and politically. According to the National Population Council
(CONAPO, 1996, cited by Iraizos-Bravo, 1999), 70% of the inhabitants of the state lived
in communities of less than 5000 inhabitants and about 80% of the work force
(poblacio’ n economicamonte aotiva [PEA]) had incomes below two minimum wages [a
minimum wage is the lowest salary paid for one working day, as regulated by law]; the
level of income to provide enough for living is estimated at least two times the minimum
wage (Iraizos-Bravo, 1999). In 1999, the minimum wage was about 34.5 oesos per day
for Mexico City and 30.0 pﬂos per day for the state of Oaxaca [corresponding to about
3.7 and 3.2 US. $, respectively] (INEGI, 2000). The state of Oaxaca ranked second in
illiteracy (just aﬁer Chiapas); this included 20% of the population older than 15 years of
age in 1997 (INEGI, 2000). About 25% of the population in the state of Oaxaca older
than 15 years of age did not complete elementary school. Further, about 45% of
households in the state of Oaxaca lacked sewage disposal and 32% lacked potable water.
Sewage disposal and potable water are minimum indicators of the local infrastructure.

About 51% of the economy in the state of Oaxaca is dependent upon agricultural
activity. However, low wages earned by agricultural workers have forced many
families to have women and children in the agricultural work force.

Statistics on the work force in Oaxaca for the 1995-1996 sugar cane harvest,
Zafra, Programa Nacional de Jomaleros Agricolas (cited by Iraizos-Bravo, 1999),

indicated that 23,000 migrant workers in Sinaloa, in the north of Mexico, were younger

23

than 14 years of age. They represented 45% of total wage labor force, and the largest
contingent of the young workers came from Oaxaca. The earnings of youth are thus
becoming a critical component for the family’s economy. However, the adverse
working conditions and inadequacy of health care and education for working youth
places them at high risk with a progressive deterioration in quality of life and little
hope for a better adult life (Arboleda-Ramirez, 1999).

Comparative data on living conditions in Oaxaca between 1980 and 2000 are
shown in Table 2.1. The data indicate rather slow improvement in living conditions for
the state. However, when the same indicators are observed within speciﬁc
communities, the range of inequality is magniﬁed. For decades, the state of Oaxaca
suffered, to a large extent, from ups and downs related to government agricultural and
social policies and strategies that offered the hope of progress, economic improvement,
and better quality of life for the area. The state has experienced signiﬁcant changes in
forms of production and resource allocation, but none of the strategies have apparently
succeeded in offering enough resources to families to earn a decent living. It is not an
accident that, given the heavy reliance of the. state of Oaxaca on agriculture, its
population has been struggling to survive the attacks of land reform and economic
measures that have created the conditions that prevent the population from reaching
food autonomy, reliability, and sustainability. Therefore, analysis of nutritional deﬁcits
in the population and its functional consequences are of central importance (Arboleda-

Ramirez, 1999).

Urban-Rural Contrasts in Mexico and Latin America

Urban-rural contrasts in many developing countries of Africa, Asia and Latin
America are magniﬁed by chronic nutritional problems in the rural areas, in addition to
marked economic inequities. In the more developed countries of these regions, the

urban-rural contrast in growth and maturity reﬂects SES variation, i.e., the larger size

24

and earlier maturity of urban children reﬂects the better-off economic circumstances
and access to resources of city residents (Eveleth and Tanner, 1990).

Urban-rural comparisons of the growth status of Mexican children date to the
19603. Vega-Franco and Robles-De la Vega (1962) estimated the nutritional status of
urban school children from Durango (north central Mexico) with height and weight. A
sample of 11,406 children, 6 to 12 years of age from public schools (5,917 males and
5,489 females) was measured in 1961. Adequate nutritional status corresponded to a
height within 15% and weight within i 10% of Mexican reference data (Ramos
Galvan, 1960). There was a deﬁcit in weight that increased with age in males and
females, beginning at 7 and 8 years, respectively, which lead to an increase of ﬁrst-
degree undemutrition in males and ﬁrst and second undemutrition degree in females
(Gomez criteria, see below). Height was normal in 74% of males and 68% of females.

Perez-Ortiz and Mora (1967) assessed the growth status of a sample of school
children, 7 to 14 years, from rural community in Tlaltizapan, Morelos, between 1962
and 1963. The sample was characterized by having low weight and most of the children
were classiﬁed as having ﬁrst degree undemutrition according to Gomez classiﬁcation,
which is based on weight-for-age. In the Gomez protocol, nutritional status is
determined as follows: (actual weight / ideal weight for age X 100). The Gomez scale
has the following categories: (1) overweight > 110%, (2) adequate 91-100%, (3) ﬁrst
degree undemutrition 76-90%, (4) second degree undemutrition 61-75%, (5) third
degree undemutrition <60% (Gomez, 1946, 1956).

Weight and height were almost equally affected in the rural children from
Morelos, and females were more affected than males. On the other hand, males had
more weight-for—height from 9 to 11 years, which suggested a tendency towards
overweight for these groups.

Table 2.2 compares the mean weights and heights of urban children from

Durango with the corresponding values for rural children from Morelos. Although the

25

children are from different geographic regions, both series date to the early 19603, and
may represent the trend for urban-rural differences at this time. Weight differences
were larger in boys (2.5 to 3.5 kg) than in girls (0.8 to 3.3 kg). Height differences were
also greater in boys (4.5 to 7.0 cm) than in girls (3.0 to 7.0), except at 10 years when
the difference between urban and rural girls was greater than the difference between
boys. This probably represents sampling variation in the cross-sectional samples.

Perez Hidalgo and colleagues (1965) compared the growth status of urban boys,
7-14 years of age, in Mexico City from high (n=1067) and medium (n=505)
socioeconomic status (SES) and a sample of boys from a rural community close to
Mexico City (n=425). Children of urban medium SES were taller and heavier than rural
children at all ages. However, compared to US. reference values (University of Iowa
charts), the Mexican children of high SES had an average height that was 15% lower
and an average weight that was close to the median for US. children. Comparison of
the urban and rural children in Table 2.3 also indicates smaller urban-rural differences
than those in the Durango-Morelos comparison (Table2.1). Mean differences for weight
were 0.5 to 3.3 kg at ages 7 to 12 years of age and reached 4.8 kg at 13 years.
Differences for stature ﬂuctuated between 2.0 cm and 5.2 cm.

Comparative studies for the 19703 are based on urban-rural and high-low SES
samples. Pryor and Thelander (1972) compared the grth of 382 urban and 439 rural
school children, ages 6 to 15 years, from southern Mexico (Oaxaca and Chiapas) to
American children from California. Among Mexican children, there was very little
difference between heights of the urban and rural samples until adolescence, although
urban children were slightly taller at most ages. Beginning at age 10 in girls and 11 in
boys, consistent differences showed that urban children became taller than rural
children. Compared to Californian children, Mexican boys and girls had heights that
were one standard deviation below the mean from 6 to 9 years and then 1.5 standard

deviations below the mean from 10 to 12 years. Unfortunately these data are reported

26

only graphically and the actual values are not available (Thelander personal
communication to R.M.Malina).

A comparative study of urban school children from high SES (162 females, 156
males) and low SES (275 females, 226 males) in Mexico City (Villanueva, 1979)
showed considerable differences between the groups. The difference between high and
low SES children reached, on average, up to 4 cm for height and 2 kg for weight. The
samples were also compared to middle class Mexican children (Faulhaber, 1976), to
high SES Mexican children (Ramos-Galvan, 1975), and to British reference data
(Eveleth and Tanner, 1976). Boys and girls from high SES compared well to the
average heights of high SES Mexican children (Ramos-Galvan) and British children
(Eveleth and Tanner), but were above the urban middle class Mexican children
(F aulhaber). The high SES girls were heavier than girls from lower SES and the
middle class sample (Faulhaber), but were lighter than British and high SES Mexican
children. In contrast, high SES males were consistently heavier than their lower SES
peers and the middle class sample, but were similar to reference values for British
children and the high SES Mexican reference between 7 and 10 years; subsequently,
their weights were heavier. The differences in height and weight between high and low
SES Mexican children are shown in Table 2.4. Differences in weight ranged from 0.7
to 3.3 kg in males and from 1.2 to 3.5 kg in females, but did not follow a pattern across
age groups. The differences in height ranged between 3.5 to 5.7 cm in males and from
3.4 to 6.3 cm in females. The largest difference occurred at 10 to 11 years of age in
girls, which was interpreted as reﬂecting earlier sexual maturation (Villanueva, 1979).

The grth of 554 school children, 6 to 15 years of age (287 males and 267
females) from Indian communities from Chiapas was reported by Aréchiga and Serrano
(1981). Heights and weights of rural children were considerably below the urban
Mexican reference for high SES children (Ramos Galvan) and middle SES children

(Faulhaber) at most ages in both sexes (Table 2.5). The differences in height and weight

27

were considerably larger than indicated in the comparisons cited above, reﬂecting the
impoverished circumstances in rural indigenous communities in southern Mexico.
However, the urban-rural differences were of similar magnitude in boys and girls.

Nutritional status and food intake were assessed in three rura1 villages of
Guanajuato, a north central state of Mexico, by Eastwood-Garcia et a1. (1990) with the
purpose of identifying patterns of food intake and growth stunting in preschool children
(33 to 60 months of age). The observational study collected data on 45 children (24
males and 21 females). Stunting corresponded to height-for-weight below three
standard deviations of reference values. The children had experienced a reduction of
linear growth due to past insults, but were not currently overly thin. Although the
children were beyond the period of greatest vulnerability, it was apparent. that catch-up
growth did not occur.

Butte et a1. (1993) followed the weights and heights of infants in Capulhuac, a
rural farming community in the northern Mexico, at monthly intervals from birth to 6
months. Growth faltering was evident at 6 months. Assessment of energy expenditure
indicated that energy utilization was impaired as a result of malabsorption and/or
micronutrient deﬁciencies, and possibly illness. More importantly, the energy intake
was not appropriate to support catch-up growth.

Lagunas-Rodriguez and Jimenez-Ovando (1995) conducted a study of Otomi
youth, 6 to 20 years of age, living in the northwest part of the state of Mexico. The
cross-sectional sample of 518 males and 489 females was studied between 1978 and
1987. Although living conditions in the Otomi region were slightly better than those
that were common in Chiapas, a similar growth pattern was apparent upon comparison
with to the urban middle class sample of Faulhaber (1976). The differences increased
with age and ranged from 6.4 to 15.5 cm for height in males and from 4.0 to 10.4 cm
for height in females. The largest differences occurred at 13 year in males and at 12

years in females (Table 2.6). Unfortunately, body weights were not reported.

28

Lopez-Alonso (1995) reported on the growth of children in three North Sierra
communities in the state of Puebla in late 19703 and the late 19803. The samples were
from Zacapoaxtla (n=374) and Caxhuacan (n=332), which are predominantly Nahuatl-
speaking communities. The third community was Mecapalapa (n=383), a Totonaco-
speaking community. The sample included youth 8 to 18 years of age. The particular
interest in the groups was related to isolation resulting from geographic barriers since
they lived in the Sierra Madre region. Growth in height and weight was compared to
the urban middle class samples of F aulhaber ( 1976, 1989) using z-scores. At 8 years,
both males and females from Zacapoaxtla and Mecapalapa had heights slightly below
the urban reference, but with increasing age males from Zacapoaxtla lagged behind the
reference by -0.5 to -1.5 SD units from 9 to about 15 years of age. The Caxhuacan
samples presented a poorer picture; boys had heights that varied between -1.5 and —2.5
SD units between 8 and 15 years of age, and girls showed heights more than —3 SD
units at most ages. Body weights showed a similar pattern, but deﬁcits were not larger
than -2 SD units. The results indicateda greater effect on height than on weight. The
apparent sex difference in the magnitude of the deﬁcit was attributed mainly to
preferential treatment of males inﬂuenced by local rearing practices.

Cities in many developing countries of the world are currently expanding as a
result of continuous rural to urban migration. Estimates for the year 2000 showed that
Latin America appeared to be the most urbanized region of the developing world.
Latin America urbanization has been associated with high rates of population growth,
and until the 19603, the urban population was highly concentrated in the main cities as
in the cases of Montevideo, Buenos Aires, Mexico City, Caracas, Santiago, Lima, San
Jose and Panama City (Valladares and Coelho, 2000). Although the rural-urban
migration later shifted to medium-sized cities, population mobility continues to be a
challenge when recession, scarcity of resources, and poverty are highly prevalent in

urban settlements characterized by poor living conditions.

29

Quite commonly, migrants ﬁ'om rural areas form irregular settlements on a city’s
edge. Such neighborhoods are variously labeled in the literature, but a common term

appears to be “shanty towns.” Names for such neighborhoods in Latin American

 

countries include favelas, barriadas, pueblo jovenes, and colonias populares. Health and
nutritional conditions associated with migration are generally poor (Malina et al., 1980b;
Malina, 1990).

Malina et a1. (1981) considered the growth status of children from six communities
in the Valley of Oaxaca in southern Mexico in the 19703: two rural indigenous, Zapotgo-
speaking communities, two rural Cm communities (more westemized and
progressive), and two urban ms. Boys in the M3 were slightly, but consistently,
taller and heavier than boys in rural indigenous communities, but girls in the communities
did not differ in height and weight. In contrast, children from the rural Ladino

communities were slightly better off in height and weight compared to those in the

 

colonias and rural Zapoteo communities. Urban oolonia and rural girls also did not differ
in age at menarche (Malina et al., 1981). Of interest, rural to urban migration (i.e.,

children in the colonias) did not necessarily result in improved grth status since the

 

differences between rural Ladino and urban children were small (about 0.5 kg for weight
and 2 cm for height). On the other hand, the comparison clearly indicates the relatively
poor nutritional status of children from rural indigenous communities (see Malina, 1990).

Graham et a1. (1979, 1980) noted generally similar results for Peruvian children.
Differences in height and weight were small between rural children from northern
villages and poor urban children from the capital city of Lima. Rural boys were slightly
shorter, but no differences were observed for rural and urban comparisons of stature in
girls. Height and weight ratios suggested that, on average, rural children carried less
weight-for-height than urban children.

Given the relatively high rate of migration from rural to urban areas in Latin

American cities (as well as in other parts of the developing world), the need for ongoing

30

studies of the growth status of children who migrate with their families is highlighted.
With a longer duration of residence in urban areas, grth status may improve compared
to children in rural areas.

Urban-rural differences in growth can be summarized as showing two different
trends, one for developed and the other for less developed countries. In the case of United
States and most European countries, the earlier advantage of rural children over urban
children was reversed from the 19503 to the 19803, resulting in taller and heavier children
in urban compared to rural areas settings. Afterwards, no urban-rural differences are
observed, which appears to indicate that living conditions for both urban and rural
population are very much alike. In contrast, in some European countries as well as in
Latin American countries an urban—rural difference that favor living conditions for urban
children involve not only growth but also maturity. These trends are evident among
children and young adults in the case of Poland, children and adolescents in China, and,
especially children, adolescents and adults in Africa and Latin America.

The rationale for emphasis on the urban-rural gradient for populations where such
differences exist is their common origin, i.e., most differences result from unequal
access to economic resources that negatively impact quality of life. In general, the high
concentration of economic resources, facilities and health services in cities of less
developed areas of the world makes urban dwellers a privileged sector of the
population. At the same time, this kind of urbanization raises physical and economic
barriers that prevent children living in rural areas from having access to adequate living
conditions and, therefore, for reaching they full growth potential. In the case of
Mexico, the urban advantage over rural living conditions has prevailed for more than
three decades, if not more, which indicates that not enough has been done to improve
the living conditions and quality of life in rural areas. This is especially evident in two
well studied rural, indigenous populations such as the Mega of the Yucatan

(McCullough, 1982) or Zapotecs of Oaxaca (Malina et al., 1980, 1983). Both

31

Yucatecan mm and Oaxaca Zapotecs have showed very little or no improvement for
most of the 20th century, at least through the 19703.

Such conditions are comparable in the Totonaco—speaking and the Nam—tia-speaking
communities studied by Lopez-Alonso (1995). Quality of life also has not improved for
indigenous communities in Chiapas, one of the most marginalized areas of the country,
which is experiencing recent social movements demanding better use of natural resources
to improve their lives. The rural populations, living under the more difﬁcult conditions
are, to a large extent, indigenous. The Otomi population studied by Lagunas-Rodriguez
and Jimenez-Ovando (1995) is slightly better-off, though with weights and heights that
still fall below those of urban populations. It is possible that one of the advantages of this
group is its relative proximity to Mexico City, which may translate into easier access to
better resources. Therefore, when they are compared to those who have both economic
and the geographic disadvantages which set them farther away from major urban centers,
living conditions then appear to be better off than other indigenous groups.

There is then a need for more precise and up-to-date information on the health
and growth status of children in rural communities of Mexico. Promotion of health and
nutritional programs to improve living conditions of marginalized people at present has
to start with the knowledge of the extent of rura1-urban differences and with more
precise information of how they affect children, and, moreover, to what extent they
affect the ability of adults to obtain daily living resources. The ability to develop such
basic information required to implement adequate nutrition, health and education
programs that respond equally to the needs of urban and rural populations may be

expected to reduce the gaps that presently exist.

Functional Consequences of Undernutrition
Risk factors for growth retardation associated with chronic undemutrition include

seasonal changes in food availability, disease, poverty, and overall deprivation. Frequent

32

infections may also contribute to reduce rates of grth in length and weight. Although
improvements in sanitation and health care help to reduce the risk of some diseases,
recovery from infections increases the nutritional demands on the organism. An adequate
diet must account for the dietary requirements for catch-up after a bout with infection.

Because undemutrition affects a large sector of the population in developing
countries, it is a major, worldwide public health concern. Nutritional deﬁciencies can
have long term consequences at different levels, ranging from poor mental
development, to impaired physical growth (stunting), to limited physical working
capacity (Allen, 1993; Pollit et al., 1996; Scrimshaw, 1996).

The association between changes in weight-for-height and linear grth in
children from poor environments is considered a response to marginal dietary intakes
over time, which allows overall growth to proceed but at a reduced rate without the
children becoming wasted. This mechanism appears to insure proportionate grth
under critically low energy and nutrient intakes.

Marginal nutritional status, sometimes labeled mild-to-moderate undemutrition,
is presently highly prevalent in developing countries more so than more severe forms
of undemutrition. The World Health Organization (Onis et al., 1993), based on surveys
conducted from 1980 to 1992, reports that most countries in Latin America have a low
to moderate prevalence of underweight among preschool children (birth to 5 years of
age). However, there is considerable variation in estimates among countries and within

speciﬁc countries.

Cognitive and Behavioral Consequences of Undernutrition

Studies that focus on the impact of early undemutrition on cognitive development
were mainly concerned with its potential inﬂuence on mental development, and over
the long-term, reduction of opportunities for success in school. For adults, such

persistent conditions would affect the development of skills necessary to earn a living.

33

Mild-to moderate undemutrition is recognized as a developmental risk factor in this
regard (Pollitt et al., 1996; Winick, 1993).

Effects of undemutrition on social and emotional development have received
limited attention. Several studies have shown that social and emotional development
are sensitive to undemutrition, so that marginal nutrition can affect a child’s ability to
adapt to his/her social and educational environments (Espinosa et al., 1992; Gardner
and Grantham-McGregor, 1990; Grantham-McGregor et al., 1991).

Information on the consequences of deﬁcient nutrition on behavior has been
derived from intervention studies of nutritional supplementation in poor communities.
Among these, the Jamaican study provides valuable information to understand distinct
levels of response to limitations imposed by food scarcity (Grantham-McGregor et al.,
1991; Powell et al., 1985, 1995; Walker et al., 1996). The initial study examined the
relationship of background variables such as nutritional status and socioeconomic
conditions, on developmental level. Limited stimulation in the home environment was
presumed to explain the observed decline and gender differences favoring girls over
boys, since girls tended to perform better in school than did boys. The study also
suggested that mental development was more likely to be affected when malnutrition
was experienced for longer periods. Nutritional supplementation had beneﬁcial effects
on the mental development of stunted children. The beneﬁcial effect of
supplementation continued for about six months, whereas the simple stimulation effect
diminished faster. The ﬁndings supported the hypothesis that at least part of the deﬁcit
in behavioral development was attributable to undemutrition.

The Nutrition Collaborative Research Support Program (CRSP) was conducted
in three different countries (Egypt, Kenya, Mexico) with contrasting diets to determine
the relationships between energy intake and several outcome variables, including
growth status, psychological development, pregnancy, lactation, behavior and

morbidity (Allen, 1993). Food intake was measured at the household level by

34

collecting information on food preparation and consumption inside and outside of the
household. Food availability was considered adequate in Egypt since animal products
provided, on average, 18% of energy (compared to approximately 40% for children in
the United States). The communities in Kenya had serious deﬁciencies in production
that were reﬂected in the poorest nutritional situation; preschool children obtained only
about 8% of energy intake from animal products. In the Mexican communities, only
12% of the energy intake came from animal products and 60% from carbohydrates
(Allen, 1993).

Measures of cognitive and behavioral development were administered to infants
at three and six months of age, to preschool children at 18, 24 and 30 months of age,
and to school-age children at the time of school entrance. Neurobehavioral
performance in infants and preschool children was estimated with the Bayley scales of
motor and mental development. The cognitive and behavioral outcomes suggested that
growth stunted children of all ages performed less well than non-stunted children.
Infants whose mothers consumed more animal products and had better quality diets,
smiled more often. Maternal status for micronutrients (iron and vitamin B 12) was
positively associated with infant performance on the Bayley motor and mental scales at
three and six months of age. Observations of Mexican preschool children also showed
that those whose growth was stunted because of poor quality diets had behavior
characterized by apathy, long periods of time of doing nothing and crying, and reduced
interactions with others. In contrast Egyptian and Kenyan children whose diets had
more animal products played and verbalized more often, and used symbolic play, which
is predictive to some extent of later cognitive development.

Data from an earlier study in Mexico (Chavez and Martinez, 1984) of
supplemented and non—supplemented children in a small agricultural community
considered relationships between food consumption and behavior early in life. No

differences were detected in direct observations of activity, behavior, and mother-child

35

interactions in the ﬁrst eight months of life, with several signiﬁcant exceptions. Children
who received the supplement were more active than the unsupplemented children.

Play behaviors from six months to one year of age also varied between the
groups. Children who were shorter and had less weight, i.e., undernourished, showed
reduced verbal interactions by about 50%, reduced imaginative play by about 20%, and
an increased tendency to cry more often than better nourished children. Overall,
chronic undemutrition depressed physical activity and interpersonal interactions with
the parallel consequences of limited stimulation during the ﬁrst year or two of life.

The long-term effects of early protein-energy malnutrition were described by
Cravioto (1980) in a follow-up study of 18 severely malnourished infants in another
rural Mexican community. Children who were severely malnourished and hospitalized
during the ﬁrst two years of life and subsequently rehabilitated, were followed and
compared to children in the same community who were not undernourished early in
life. Motor development scores during the ﬁrst three years of life (Gesell scales)
declined with age. About 28% of the variation in the motor development scores at one
year and 45% at two years could be explained by body weight, whereas the proportions
of variance in motor development scores explained by length at one and two years were
18% and 38%, respectively. At school age, the motor performances of the severely
malnourished children after nutritional recovery were poorer compared to control
children in the community. The differences were especially marked for coordination,
agility and balance.

The CRSP study cited previously (Allen, 1993) also included school-age children
who were tested on Raven’s progressive matrices as a measure of overall intellectual
ability. Energy intake remained a signiﬁcant predictor of intellectual ability when
socioeconomic status, maternal anthropometry, gender and sanitary conditions in the
communities were statistically controlled. Energy intake was a signiﬁcant predictor of

performance on the Raven task. The association between dietary patterns and attained

36

body size and growth in school children showed that better nutrition (diet quality but
not energy intake) was a strong predictor of weight, height and weight gain in Mexican
children, while in Kenya the diet predicted only weight gain. Data for Egypt where
meat consumption was higher, showed that the inﬂuence was on height gains.
Morbidity also explained some degree of growth failure in all three countries, since
toddlers consumed less food during illness, falling to lower levels in Mexico and
Kenya. The results suggest that chronic undemutrition places children at risk for lower
levels of attention, difﬁculties in learning, poor school attendance, and achievement.
Thus, a process that begins early in life in many communities in the developing world
has a toll at school age (Pollit et al., 1996).

Richardson et a1. (1972) analyzed the long-term consequences of severe
malnutrition in early childhood at school age in 74 Jamaican boys who were
hospitalized during the ﬁrst two years of life for marasmus, kwashiorkor, or both. The
children were about 6 to 10 years at the time of follow-up. Teachers assessed behaviors
in the school setting. The index boys, i.e., previously malnourished boys, were less
able to pay attention in class than classmates, but did not differ from unaffected
siblings, i.e., their siblings in the same household who were not hospitalized for
malnutrition during the ﬁrst two years of life. The previously malnourished boys were
signiﬁcantly less cooperative, showed fewer social interactions, and tended to be
isolated and withdrawn, or to be more often disliked by peers in school. There was no
systematic association between age at hospitalization during the ﬁrst two years of life
and the degree of behavioral impact, but this may reﬂect lack of information on
maternal conditions during pregnancy or both maternal and familial conditions after
hospitalization. Nevertheless, social domains and interactions at school age were
affected by severe malnutrition early in life.

Physical activity levels, emotional states and social behaviors of children from

Kenya who had mild-to-moderate undemutrition were described by Espinosa et a1.

37

(1992). Food intake was assessed during behavioral observations and by direct
measurements, and social behaviors were directly observed in unstructured settings.
Information on socioeconomic status, parental literacy, duration of schooling, and
school attendance were also considered. Playground observations were conducted
during regular school breaks and included activity levels (classiﬁed as high and low),
emotional states, and social interactions (peer involvement, no peer interactions,
aggression, leadership). Observations were conducted during 40-minute school breaks
for each child over 6 to 8 months. Weight-for—age and weight-for—height were
signiﬁcantly associated with higher activity levels at the beginning of the study.
Better-fed children also showed more positive affect. Overall, playground behaviors of
school children appeared to be related more to the adequacy of caloric intake than to
speciﬁc nutrients; in contrast, fat and animal protein intakes appeared to be more
closely related to the cognitive development of children followed up to 5 years. The
results suggest that an adequate level of energy intake is essential to maintain levels of
physical activity on the playground, whereas a diet of higher quality (i.e., balance of
protein and energy) is essential for the development of cognitive skills. Cognitive
skills at school age were also inﬂuenced by previous nutritional status.

Martorell (1995) summarized the Institute of Nutrition Central America and
Panama (INCAP) study of early supplementary feeding and cognition in adolescence.
The study was based on data collected in two periods, nutritional supplementation during
pregnancy and the ﬁrst seven years of life in four rural communities in Guatemala
(1969-1977) and a cross-sectional follow-up of former participants during the teen-age
years. The study assessed the differential effect of two supplements with different
proportions of energy and protein (163kcal/682kJ and 11.5 g protein vs. 59kcal/247 U
and 0g of protein) made available to mothers, infants and young children. Performance
during adolescence was assessed on a battery of educational and information processing

tasks. The participants who received the protein supplement between birth and three

38

years of age scored signiﬁcantly higher than adolescents who were given the non-protein
supplement. The previously protein supplemented adolescents had especially faster
reaction times in information processing tasks. The supplementary protein feeding
provided during the ﬁrst three years of life also had a long-term inﬂuence on academic
performance in adolescence (reading, vocabulary, and mathematics).

Reaction time was also assessed in a study of 85 undernourished, Indian rural
school children, 11-14 years of age, who were randomly selected using as a reference
their nutritional status during the ﬁrst ﬁve years of life (Agarwal, 1998). Assessments
with audio-visual reaction time (RT) and electromyography were performed. Early
malnutrition was associated with prolonged RT compared to controls with adequate
nutrition during the ﬁrst ﬁve years of life. Total pre-motor and motor RT for audio as
well as visual stimuli were affected in the previously undernourished children, and RT
also increased with the severity of current nutritional status. An additional observation
was that the children who suffered undemutrition during early childhood but who
achieved normal nutritional status at school age remained slow in processing auditory
and visual information compared to children with normal nutritional status. This study
suggested that undemutrition early in life affects perceptual abilities, information
processing and analytical capabilities at school age, but also that current nutritional
status was an additional factor (Agarwal, 1998). Nevertheless, the persistence of
impaired perceptual and information processing abilities suggests a functional
deﬁciency associated with early malnutrition that is unlikely to recover.

In an earlier study, Agarwal (1993) assessed the effect of long-term, chronic
malnutrition in rural Indian children. Two age groups were studied, 0-3 and 6-8 years.
Functions such as immediate memory, reasoning, language and comprehension were
negatively affected by undemutrition. Motor coordination was signiﬁcantly affected in
early childhood, but was somewhat improved at school age, which suggested that the

school environment may have provided stimulation to offset earlier effects and lead

39

to improved motor function. On the other hand, the undernourished children showed
poorer attainment in personal independence, individual responsibility, self-sufﬁciency
and language development. It is important to note these characteristics inﬂuence the
child’s overall social interactions which also affect subsequent development. In a sub-
sample of wasted and stunted children (i.e., severely undernourished), observations of
neurological deﬁcits were also noted in performances on measures of ﬁnger tapping

and arm pronation-supination.

Nutritional Conseguonces for Motor Porformanco

The acquisition of basic movement patterns and skills takes place largely during
early childhood so that most fundamental motor patterns (walk, run, jump, hop, kick,
throw) are developed by 6 to 8 years. Afterwards there is, more or less, rather
continuous improvement of such abilities in more complex performances, i.e., motor
skills improve with age from childhood into adolescence (Malina and Bouchard, 1991).

Chronic undemutrition is associated with impaired motor performances as
expressed in low scores in tests of static strength, running speed, jumping, and
throwing. Measures of motor performance are, therefore, of interest in the evaluation
of health status in developing areas of the world where chronic undemutrition is
common. Performance-related physical ﬁtness refers to. . .“those components of
ﬁtness that are necessary for optimal work, motor and sport performance. It is
commonly deﬁned in terms of motor abilities and performance using standardized
tests”... (Bouchard et al., 1997, p.89). Because performance-related ﬁtness is a
multifactorial outcome, depending on speciﬁc motor skills, aerobic and anaerobic
power, body size and composition, motivation, and nutritional status, it applies to
highly skilled elite athletes as well as the general population, and to the child in
learning to run, or jump, or to aging adults whose movement activities are declining

(Bouchard et al., 1997).

40

Assessment of the performances of children must consider that physiological
demands are higher for children than they are for adults, such as the oxygen cost of
walking or running, which per unit of body weight is higher in children and may be
related to proﬁciency in motor skills (Malina et al., 1987). Different aspects of
performance are affected under chronic protein-energy malnutrition (PEM) in children.
Rocha-Ferreira et al. (1991), for example, considered the functional characteristics of 8
year old low SES Brazilian children with a history of mild-to-moderate undemutrition
(61 girls, 84 boys). Performance items included the standing long jump, shuttle run,
50m dash, 9-min run, and grip strength. Current nutritional intake was estimated from
information provided by parents (intake at home) and school records (intake at school).
There were low-to-moderate positive correlations between body size and proportions
and indicators of performance. When age and weight were statistically controlled,
stature was positively correlated with jumping, agility and 9-minute run scores.

In a study of Senegalese children 10-13 years of age, Beneﬁce (1993)
emphasized physical activity as an important component of daily energy expenditure
(EE). It was estimated that physical activity represented 31% of total BE in boys and
25% in girls. Beneﬁce also considered the effects of nutritional status on the physical
activity and motor performances of this sample of Senegalese youth 10-13 years of age.
Physical activity was estimated from direct observation, and performance tasks
included the 35 m dash, a submaximal step test, the standing long jump, hand grip
strength, an overall ball throw, and vital capacity. The Senegalese children had deﬁcits
in height and weight that were associated with lower performances than observed in
well-nourished children.

The strength and motor performances of school children 6-14 years of age from a
rural indigenous community in the Valley of Oaxaca, Mexico (Santo Tomas Mazaltepc)
were studied by Malina and Buschang (1985) and Malina and Little (1985). The mild-

to-moderately undernourished school children had absolutely lower levels of strength

41

and motor ﬁtness compared to well-nourished children. However, when body size was
controlled, i.e., per unit height or weight, grip strength was commensurate with their
small body size, but running and jumping performances were less than expected. In a
subsequent study, the performances of these rural Mexican children were compared to
school children of the same age from an island community in Papua New Guinea
(Malina et al., 1987). Grip strength and the same motor tasks were measured in both
studies. The growth status of the two samples approximated the 5‘“ percentiles of US.
reference data, which suggested that the samples as a whole probably experienced
chronic mild-to-moderate nutritional stress during infancy and early childhood. The
performances of the rural Mexican children were below those of the Papua New Guinea
children and a corresponding sample of American children the same age and sex.
When expressed per unit body size, the performances of the Papua New Guinea
children compared favorably to those for the American children, but those of the
Mexican children did not, especially for the dash and standing long jump.
Interestingly, performance on a ball throw for distance per unit body size was better in
the Mexican and Papua New Guinea samples than in the American sample. The
throwing performances were likely related to patterns of life style observed in both

communities compared to those of the American children.

Nutritional Status and Physical Working Capacity

The long-term effect of chronic undemutrition on physical working capacity has
been a matter of debate in terms of quality of life and economic productivity. Smaller
individuals appear to require less food to live and to move, and seemingly perform well
in activities that demand low level of energy expenditure. On the other hand, many
studies show that small body size is disadvantageous in conditions of moderate-to-heavy
work (Allen, 1990; Buzina et al., 1989: Calloway, 1982; Desai, 1984; Ferro-Luzzi, 1985;

Satyanarayana et al., 1979; Spurr et al., 1983; Spurr and Reina, 1988, 1989).

42

Physical working capacity (PWC) represents the individual ’3 ability to perform
submaximal or maximal muscular work. PWC is measured via submaximal or
maximal power output, submaximal oxygen consumption, or maximum oxygen
consumption (VOZmax, peak V02). PWC is often used as an indicator of health status
in adults in societies with economies that depend upon physical labor in agricultural or
industrial production. Deterioration of PWC is often observed in populations where
chronically marginal nutritional conditions are common. Moreover, when the
compromised nutritional status also involves iron deﬁciency, which has an important
role in oxygen transport, PCW is more affected (Buzina et al., 1989). Therefore, the
concern for poor nutrition is not restricted to energy and protein, but also to
macronutrients and micronutrients that are known to affect physiological functions
essential to physical work, immunological competence, behavior and cognition.
Although causes vary from country to country, economic deprivation and disease are
generally central to the issues at hand.

Despite of the general assumption that in developing areas physical work
capacity is of prime importance to obtain resources for survival, energy requirements
vary with degree of complexity in each society (Ferro-Luzzi, 1985). As an example,
subsistence economies of modern hunter-gatherers require rather moderate physical
effort to meet their needs, whereas agricultural communities demand more work from
their members. A peasant farmer in a pre-industrial system represents the next level of
intensity of energy input and his energy expenditure is considered in the high range
without taking into account intermediate periods of activity. In terms of the necessary
adjustments to carry on physical work, it has been suggested that the upper limit of
work that can be tolerated for an 8-hour shift corresponds to a level of physical activity
that approaches 35% to 40% of an individual’s VOzmax. The malnourished individual
with reduced PWC responds either by working at a higher proportion of VOzmax or by

producing less than the well-nourished person performing the same work task.

43

Several studies have observed association between marginal nutritional status and
physical work performance in youth from different populations. Satyanarayana et a1.
(1979), for example, considered the physical working capacity of boys who were
observed between 1 and 5 years of age and then observed again at about 15 years of age.
Physical working capacity was measured on bicycle ergometer as power output at a heart

rate of 170 beats per minute (PWC ). The boys were classiﬁed by their nutritional

no
status during early childhood, expressed as standard deviation scores for height (i.e.,
degree of growth stunting). The boys who were most severely stunted in growth during
early childhood were at a signiﬁcant disadvantage compared to nutritionally normal boys
(based on height standard deviation scores during early childhood) in PWCm. They also
had to work at a higher rate to achieve the same power output.

Desai et al. (1984) measured the effect of marginal nutritional conditions on the
physical working capacity of adolescent offspring of agricultural migrant workers in
Southern Brazil. Nutritional status was estimated by 24-hour dietary recall. Body size,
biochemical data (lactic acid levels), and PWC (heart rate and oxygen consumption
during a submaximal bicycle ergometer work) were measured. Well-off Brazilian boys
of the same age served as a control group. Physical grth and estimated fatness and
muscle mass of the adolescent offspring of migrant workers were low. Although
oxygen consumption of the migrant children at submaximal work loads (0, 25, 50,
75w) was similar to that of the controls, the former worked at a higher percentage of
their maximum work capacity as indicated by signiﬁcantly higher heart rates for the
same oxygen consumption. Higher blood lactic acid levels in the migrant adolescents
suggested that considerable physiological stress was experienced. PCW 170 was
signiﬁcantly reduced by about one-third in the migrant adolescents, 643:62 kpm/min
vs. 905 _+345 kpm/min. The differences were attributed to reduced body mass, which

represented the effect of chronically compromised nutritional conditions during

childhood on both PWC and growth.

44

Spurr (1990) summarized a series of studies on the effects of nutritional status on
PWC and productivity in adult males and of nutritional status and growth on the PWC in
school aged children 6-16 years of age in Cali, Colombia. Well-nourished and marginally
undernourished children were included in the study. The undernourished group had
reduced grth and subcutaneous fatness, and a signiﬁcantly delayed grth spurt and
sexual maturity. Absolute VO2 max values were signiﬁcantly lower, with larger
differences for girls than for boys. However, per unit body mass, VOzmax was generally
similar between the marginally undernourished and well-nourished children.

An estimate of daily energy expenditure among Colombian children was based on
heart rate. Heart rate was used to estimate daily energy expenditure and energy
expenditure in physical activity. To answer the question of how undernourished boys
would respond to increased levels of energy expenditure, physical activity was
intentionally modiﬁed. Fourteen nutritionally normal and 19 marginally
undernourished boys 10-12 years of age participated in a summer day camp. During
the sport activities of the day camp, the undernourished boys could not keep up with
the nutritionally normal boys as reﬂected in consistently lower estimated levels of
energy expenditure during the morning session. After a hot meal was served for lunch,
the undernourished boys were able to keep-up with the nutritionally normal boys for
about one hour, but then consistently lagged behind in energy expenditure. The
morning observations probably reﬂect a combination of a history of chronic, marginal
undemutrition and lack of breakfast, whereas the afternoon observations probably
reﬂect the provision of a hot lunch.

In contrast to the preceding studies, Haas et a1. (1995) considered the physical
working capacity of Guatemalan adolescent boys who had received different nutritional
supplements during the ﬁrst three years of life. Boys who had received the protein
supplement (see Martorell, 1995, discussed earlier in this section) had a greater V02

max per unit body weight and per unit fat-free mass than boys who had received only a

45

calorie supplement. The direction of results was the same for protein supplemented
and calorie supplemented girls, respectively, but the differences were not significant.
The preceding discussion has focused on children and adolescents. In developing
areas of the world, however, there is major concern for the functional efﬁciency of
adults who were chronically undernourished as children. Among adults, there is a need
to differentiate between working capacity and work productivity (Martorell, 1989).
Whereas work capacity is a measure of biological potential to do work, productivity is
an economic term that is expressed in terms of goods produced per unit time. Some
studies show that reduced muscle mass in stunted adult men is associated with
diminished work capacity. However, some farming and industrial activities do not
demand extremely high levels of physical work. Instead, more sedentary occupations
are more likely to require cognitive abilities, skill, dexterity, motivation, good sight,

etc., as important determinants for adequate work performance.

Summary

Urban-rural contrasts in growth and physical ﬁtness in different populations
show variable results. In most developed countries, urban-rural differences in growth
and ﬁtness are negligible. In areas where such contrasts persist, e.g., parts of Eastern
Europe and Latin America, the urban-rural differences largely reﬂect inequitable
distribution of resources. In contrast to Eastern Europe, the urban-rural contrast in
Latin America also reﬂects major differences in nutritional and health status. The
rapid growth of urban centers and slums in Latin American cities is an additional
problem. These areas are inhabited largely by migrants from rural areas and health
and nutritional conditions are quite different from other areas of urban centers. The
present study contrasts the growth status and physical ﬁtness of children resident in a
marginalized urban area with those of children resident in a subsistence agricultural

rural community. Two areas are separated geographically by about 25-30 km.

46

Chapter 3

Methods

The present study considers the growth status and physical ﬁtness of school
children living under contrasting conditions in two communities, one urban and one
rural, in the Valley of Oaxaca, southern Mexico. It is a part of a broader study of
secular change in growth status and physical ﬁtness of school children in the Valley
of Oaxaca (Malina, 1999).

The state of Oaxaca has one of the poorest economies in Mexico. Rural
lifestyle in Oaxaca is more traditional, based on kinship, and communities are
commonly endogamous. The economy in rural communities is based on small scale
farming of relatively small plots of individually owned land.

In contrast, urban lifestyle is characterized by more recently established,
colonias populares, which were described by Selby and Murphy (1979) as a
heterogeneous mix of classes and ethnic groups that, despite of having some urban
advantages, do not show improved health and nutritional status compared to the
economically better-off segments of the urban population.

The two communities which are the focus of the present study, Santo Tomas
Mazaltepec and San Juan Chapultepec, were chosen because they represent the
contrasting living conditions that may inﬂuence growth and physical ﬁtness of school
children. Figure 3.1 shows the geographic location of communities. Moreover, both
communities were studied systematically approximately 30 years earlier, thus
permitting a unique secular perspective. Thus, reasonably extensive information on
growth status and living conditions is available from earlier studies. These earlier

contacts also facilitated access to both communities for the present study.

47

Conditions in the Valley of Oaxaca

The Valley of Oaxaca includes the largest area of the altiplano of Oaxaca. It
includes the state capital, mxaca de Juarez, and the Monte Alban and Milk!
archeological sites. The valley is divided into four areas, the ELIa, Tlacolula and
Zimatlan valleys, and the Man, EiLla and Mihautlan areas. The major source of
water is the was; River, which starts northeast of Oaxaca. It collects water draining
from the mountains and also from the Tlacolula River which passes through Mitla. For
most of the year, the water level in the Am River is rather low by the time the river
reaches the Valley of Oaxaca. Water levels change dramatically during the rainy season,
May through September. The river also contains relatively high levels of pollutants
derived from drainage of the city of Oaxaca, chemical from the wood industry, and
agriculture. Additional factors affecting water levels in the river are water extraction
from wells and deforestation. The Atom River and its branches inﬂuence agricultural
production in the Et_la, Tlacolula and Zimatlan valleys (Rios Morales, 1995).

The Valley of Oaxaca depends mainly upon agriculture and mostly on a single
crop, rain-fed maize. Because the crops depend on precipitation, droughts cause
frequent harvest failures, whereas ﬂooding during the rainy season often destroys
seemingly ﬁne harvests. However, gradual improvements in transportation and
greater access to tractors, fertilizers and irrigation pumps during the last 25 years
have brought new possibilities to the potential agricultural market, but conditions are
inequitable among members of farming communities.

Agricultural production experienced a signiﬁcant decline in the Valley of
Oaxaca in the 1960 and persisted for some time. At this time, the economy was
developing in Tuxtepec and the Lsgrpo, which attracted migrant workers from
communities in the Valley of Oaxaca. These two areas also were involved in greater
exchange with the states of Veracruz and Puebla rather than with the capital city of

Oaxaca. This contributed to reductions in jobs and modiﬁcations of natural resources

48

associated with the economic transformation process, and forced many of the poor in
the region, including the unemployed, to look for work opportunities in the economic
developing areas of the state and even areas out of the state (Winter et al., 1988).

The rainy season in the Valley of Oaxaca begins during April and May, peaks
during June, and continues through July and August, although it is highly variable
(Dilley, 1993). Rain-fed agriculture is possible from June to September. During
drought years such as 1982, the rain-fed agriculture became impossible even during
the rainy season. Although the Valley of Oaxaca has two or three growing seasons,
95% of agricultural production takes place during the summer months (Dilley, 1993).
Maize is the most important crop, accounting for 87% of the total summer
agricultural production and 64% of the value of summer production. Almost all
summer maize is rain-fed (88%) and grown almost exclusively for human
consumption. Variation in maize production affects the region’s food supply.

Dilley (1993) emphasizes that even in good years, the Valley of Oaxaca is not
self-sufﬁcient in maize production. The deﬁcit is supplemented by imported maize.
Since 1970, the Valley-wide production, on average, was 100 kg of maize per capita
per year, whereas the average consumption was estimated as 160 kg per capita.

At present, land quality, in particular access to water, is a major factor in
determining who participates in the growing agricultural market economy. Irrigation
is necessary to ensure success for cash crop cultivation. Irrigation has increased in
the Valley due to the use of gasoline and electric pumps, with a corresponding impact
in socioeconomic structure of the community.

Both state and national governments promote cash crop cultivation and
adoption of new agricultural technology in the Valley of Oaxaca. Credits are given to
access farm equipment, chemical fertilizers, alfalfa cultivation and livestock
acquisition. According to Dilley (1993), the state of Oaxaca authorized $1.3 million

US. for agroindustries, $4.5 million for irrigation works and $1.2 million for federal

49

and rural roads in 1990 for the Valley. The modern proﬁle of agricultural economy
shows investments in new technologies for successful cash-cropping becoming an
integral part of the economy. Therefore, irrigation pumps play a very important role
and chemical fertilizers are commonly used. Another important component of the
new economic strategies is growing demand on dairy products that has doubled cattle
production in the Valley region over the last four decades (Dilley, 1993).

The Valley ﬂoor varies in altitude from 1420 to 1740 meters and is surrounded
by mountains (Kirkby, 1973). The mean annual temperature is around 20°C, with a
difference of 5°C between the mean temperatures of the hottest and coldest months.
As noted, the Valley receives about 85% of its annual rainfall during the ﬁve month
period from May through September, the “rainy season.” The interval from October
through April receives minimal rainfall and is considered the “dry season” (Kirkby,
1973). Thus, “Fall” and “Winter” in the Valley of Oaxaca are dry seasons and are

relatively warm.

The Communities
imto Tomas Mazalt_epe_c

At the time of this study in 1999-2000 the community of Santo Tomas
Mazaltepec had a high proportion of Zapotec-speaking population. Despite the
closeness to the Oaxaca city (about 23 km north), it is important to note that Santo
Tomas was still lacking urban advantages such as sewage, potable water within each
household, paved streets and public phones in 1999, when data collection of the
present study began (October 1999). Signiﬁcant changes have since taken place
during the period 1999-2001. These represent beneﬁts for the community which
were achieved as a result of active participation of its members, among them works
to develop street branches for sewage which began around January 1999 and was

completed by November 2000. The major and most expensive investment had to do

50

with a water treatment plant. The community had to put together essential resources
for the land and construction. Construction was completed in December 2001 and it
is expected that the water treatment plant will be operating sometime in 2002.
Overall, the community has experienced major improvements during the three year
term of the immediately preceding presidente municipal, who concluded his term in
December 2001 (January 1999 through December 2001).

Water is brought to the community from two rivers that join each other at about
500 meters from the village, and become the Mazaltepec River. The river lacks water
for most of the year, except for the rainy season from May to September when the
level rises considerably. The river eventually runs through San Andres Zautla and
into the Atoyac River. There is also a storage site for potable water obtained from
deep wells located about 500 meters north of the village. A water pump is used to
send the water from the storage site to the village.

Santo Tomas has a village president, who is elected to a three year term according
to the traditions of the community. Activities of the municipal government are carried
out in two units, the amntamiento and the comisariado dc biones ojidalos (commision
for the welfare of the community). The former consists of the municipal president, a

sindioo and alcalde (judge), a secretary, a treasurer, ﬁve regidores (councilmen), and

 

the tow (individuals in charge of running errands). The ayontamiento meets every
evening at the municipal building to address community issues and to take care of
requests of people from the village. If there are important decisions to be made, the
case is brought before the village assembly where only adult males participate. The
aﬂntamiento and the comisariado serve for a three year period. The presidente
municipal is elected from among the older and responsible men in whom community
members place their conﬁdence. The individual elected is not from a speciﬁc political
party, but usually has demonstrated commitment to the community and its welfare,

rectitude, and experience from participation in communal activities.

51

Santo Tomas is located in the Etla district. According to the most recent update
from the annual household survey conducted by the health center in the community, the
population in 2001 was 2046 individuals (Martinez-Julian et al., 2001), although there is
probably some degree of under-registration given the relatively constant out-migration
that is characteristic of the village. Nevertheless, the estimated population size suggests
limited population increase over the past 30 years since the population was 1423 in 1970.
Table 3.1 shows the population distribution by age group, based on data from the health
center for 2001 (the report for 2000 did not disaggregate the data by age). Differences
between the community estimates and those for the 2000 census might be inﬂuenced by
population mobility, as emigration is obviously a factor that needs to be considered. In
this context, the annual report of the health center in the community probably provides a
better indication of current conditions than the national census ﬁgures.

The community is rural. Most lands are community owned because lands are not
productive enough to provide resources for family subsistence. Maize is the main crop.

The proportion of the population that is working, i.e., economically active (15
years of age and older), varies from year to year according to surveys of the community
health center. Based on data for surveys from 1999 to 2001 (Lopez and Altamirano,
1999; Reyes-Castellanos et al., 1999, 2000; Martinez-Julian et al., 2001), economically
active individuals represented, respectively, 68%, 53% and 68% of the population. The
main occupational activities for the population also show variation by year. The
proportions of campesinos (peasant farmers) was 32%, 25% and 28% for 1999, 2000,
and 2001, respectively. Housewives represented, respectively, 17%, 26% and 32% of
economically active individuals. It is important to emphasize that housewives generate
an important source of income, largely through sale of tortillas. One-third of the
mothers of the school sample indicated that they made their living from the preparation
and sale of tortillas. School students (some from the primaria and others from the

tolesecundaria) often combine school activity with household- and farming-related

52

chores that are essential components of the family routine. Hence, school age children
over 15 years of age represent a small but signiﬁcant percentage of the working
population. The contributions of primary school children under 15 years of age are not
reﬂected in the statistics for economically active individuals, although many contribute
signiﬁcantly to the economic activities of households by helping in ﬁeld work, animal
care and herding, and household chores related to family businesses. Other
occupational activities for those 15 years and older include individuals classiﬁed as
employees (4% in each of the three years) and comerciantes (traders, 7%, 17% and
11%, respectively, in the three years). Unemployed individuals represent a relatively
small number (0.6%, 2.3% and 2.1%, respectively in the three years).

Data on average family income indicated that a large proportion of families had
incomes lower than or equal to one minimum wage (minimum salary). The percentages
were 86%, 84% and 65% for 1999, 2000 and 2001, respectively. At the time of the study
was begun (1999), the minimum wage was about 34.5 ms for Mexico City and 30.0
ms for the state of Oaxaca, which corresponds, respectively, to about 1035 and 900
rm per month (INEGI, 2000). Equivalents in United States dollars are $113 and $96,
respectively. Income reached two times the minimum wage in 14%, 15% and 35% of the
families in 1999, 2000 and 2001, respectively (Lopez and Altamirano, 1999; Reyes-
Castellanos et al., 1999, 2000; Martinez-Julian et al., 2001). An average salary of two
times the minimum wage is considered necessary to satisfy basic family needs.

At present, a number of men are employed as construction workers. Construction
is an increasingly more common source of income due to an increase in the number of
houses being remodeled or new construction in process. These improvements are largely
the result of important economic contributions sent by migrant workers to their families.
According to an informant in the community, the duration of a migrant’s economic cycle
is about three years before his/her family beneﬁts from his/her earnings. The process is

described as follows. For the ﬁrst year away from the village, they send money to pay

53

debts derived from the loans acquired to pay for the trip and expenses associated with
settlement in the new location. During the second year, the resources help to improve the
family living conditions in the new community. It is not until the third year that the
resources are invested in household improvements in the parent community (Santo
Tomas). It is interesting to note that during the interval of the study in the community
(October 1999 to March 2000), there was a signiﬁcant increase in household
improvements which appeared to show that the regular ﬂow of resources from migrant
workers have had a positive inﬂuence on the quality of life in the community.

Information in the 1998 health diagnostic report prepared by the staff of the
community health center (Lopez and Altamirano, 1999) indicated that about 93
individuals had emigrated from the community. Based on information derived from
household survey interviews in 1999-2000, the estimated number of migrants was 98.
The families surveyed indicated that more than one-half have one relative who
emigrated, while 22% and 26% had three or more members who emigrated from the
community. However, of these, only 3% had emigrated permanently.

The destination of the migrants was mainly Mexico City (about 60%), with a
smaller proportion going to the United States (20%). Migrants are primarily males
(79%). A small number are females (13%), who leave their children with their
parents (i.e., grandparents). About 13% of the males who emigrated were fathers and
66% were sons. The duration of the migration period ranged from 6 months (7%) to
2-4 years (27%) to 5-10 years (30%). The emigrants leave their families in the
village and return periodically for important community celebrations, such as di_a_d_o

muertos (November 1-2) and ﬁesta del santo patrono del pueblo (village saint’s day)

which takes place on December 18. Few migrants married outside of the community

 

and returned to the village after they had children 5-10 years later.
Social organization is still largely based on nuclear families, which represented

76% and 87% of the households in 1999 and 2000 (Lopez and Altamirano, 1999; Reyes-

54

Castellanos et al., 1999, 2000; Martinez-Julian et al., 2001). Education has continued to
improve since the earlier surveys. In the 19703, only 35% had completed between one
and six years of school. Data for the 2000 census (INEGI, 2000, 2002) showed that
among individuals under 18 years of age, 41% completed six years of school and about
37% completed secondary school. However, among individuals 18 years of age and
older, only 7% completed high school and 4% had some college education. In the period
1999-2001, only 6% of the population was described as illiterate.

A secondary school which works under the national education television system
(telesecundaria) is presently reaching a larger number of students of this level. About
100 students were enrolled in the telesecundaria at the time of the study. Signiﬁcant
improvements in the telesecundaria include a recent donation of computers for the
purpose of retaining the students in the community rather than have them attend a '
secondary school in Etla.

There was one kindergarten building. The building for the primary school had
six classrooms and enrolled a total of 367 students in morning and afternoon sessions
in 1999-2000.

The community health center provides medical care on a daily basis. Attention is
offered by one full time physician, who commutes from Oaxaca. She is helped by a nurse
and a medical student who was under internship training. One of the most recent projects
was to build a public library, which was opened for the community in March 2000.

The community is largely bilingual in m and Spanish (Lopez and
Altamirano, 1999; Reyes-Castellanos et al., 1999, 2000; Martinez-Julian et al., 2001).
Most people above 15 years of age speak 2am. Although children and
adolescents are Spanish-speaking, they are generally able to understand m.

Based on the conditions described, it is clear that community living conditions
have improved signiﬁcantly in recent years. Paved roads are only available for two

of the main streets in the village and 10 km away from the village. Transportation

55

includes buses that run from Mazaltepec to Oaxaca City on regular basis every 40
minutes on weekdays and every hour on weekends. There is also a taxi service, but it
is expensive and less frequent. There is only one public phone in the village; people
usually go to Zautla (8 km) when they need phone service. However, the road from
Santo Tomas to Zautla, and in turn to Etla is mostly paved (about 10 km).

The following housing construction characteristics were derived from the most recent
health center. Roofs were made of tile (42%), concrete (44%), and laminated board (12%).
The laminated board includes a light asbestos coating, which apparently represents a very
low level of exposure (Asbestos Institute, 2002). Walls were made of concrete or brick
(53%), adobe (40%), and wood and other materials (7%). The majority of houses (66%)
presently have cement or concrete ﬂoors; the remainder have earthen ﬂoors.

Sanitary conditions in the village have improved relative to the earlier‘survey in
the late 19703. Potable water was available for 89% of the households in 1998 and to
98% in 2001. Disposal of human wastes was dependent upon latrines in 32% of
households in 1998 and 47% in 2001. This improvement reduced the amount of open
ground used for human excrement from 52% to 35%. The use of septic tanks also
increased from 15% to 17% from 1998 to 2001.

The burning of waste materials is a persistent source of pollution, but it has
decreased slightly from 61% in 1999 to 57% in 2001. And, in 2001, the municipal
administration purchased a truck that collected waste throughout the community.
Smoke from kitchens is a persistent problem as most women still use wood and
carbon to cook tortillas.

Based on the health center report, acute respiratory conditions are relatively
common. They represented 75% of requests for treatment in 1999, but only 25% in
2000 and 31% in 2001. Intestinal infections were the second most common
complaint, 15%, 7% and 4%, respectively in 1999, 2000, and 2001 (Lopez and
Altamirano, 1999; Reyes-Castellanos et al., 1999, 2000; Martinez-Julian et al., 2001).

56

San Juan Chapultepec

The urban community San Juan Chapultepec is located on the slopes of the hills
west of the city of Oaxaca de Juarez. It is an old community which had a population of
about 5000 in 1970 (Welte, 1973). This urban settlement has expanded considerably and
its population continues to increase due to migration not only from rural areas but also by

attracting people from other states who come to work to the city of Oaxaca. At present, the

 

colonia is part of the city of Oaxaca, although its administration is based on a municipal
agent who corresponds to a large extent to the presidente municipal at the villages.

It is difﬁcult to obtain a precise estimate of demographic changes in San Juan
over the past 25-30 years. San Juan is now incorporated into the city of Oaxaca
(Oaxaca de Juarez). The following ﬁgures are estimates for the area, including

several barrios. They are based on the 1990 and 2000 censuses using disaggregated

 

information for the city of Oaxaca (INEGI, 1990, 1993, 2000, 2002). The 1990
census indicated an estimated population of 14,573, which increased to about 16,279
in 2000. Data for the area suggests slow, continuous demographic growth. Living
conditions in San Juan are closely related to the resources and administration of the
city of Oaxaca. The cm; has spread up and across the hillside which represents
the newer and more crowded areas, or the so called Mos. There is still a dynamic
participation of community members in activities of common interest, such as
building facilities and maintaining public areas (schools, parks and sport facilities) or
cleaning ﬁelds. Adults congregate on weekends to undertake this shared community
work called “M”. It represents the family contribution to community well-being.
Characteristics of the urban population resident in the m can be gleaned
from a study in the mid-19703 (Graedon, 1976), the 1990 census (INEGI, 1990, 1993),
the 1995 update (INEGI, 1995), and the 2000 census (INEGI, 2000, 2002). The
population is basically Spanish-speaking. In the earlier survey, education was, on

average, three years, and 20% of the heads of households were illiterate. In contrast,

57

estimates in the 2000 census indicate that 82% of the San Juan Chapultepec population
15 years and older was literate and that they had an average of 8 years of schooling.
About 20% of the adult population 18 years and older completed elementary school
(W), about 20% completed secondary school (secundaria), and 18% reached high
school (preparatoria) (INEGI, 2000, 2002). There are presently two kindergardens and
three primary schools within the m. The schools work only as morning sessions.
There is a television-based secondary school (telesecundaria) next to the agonoia

municipal in the colonia, and about 190 students were enrolled in 1999.

 

Average household size was six persons in the previous study in the mid-19703
(Graedon, 1976). The 2000 census indicated an average of 4.2 persons per household
(INEGI, 2000). Time of residence in the oom varied from 6 months to more than 20
years in the 1990 census (INEGI, 1990, 1993), which reﬂects the high mobility of the

urban population. Data from the 2000 census indicated that 81% of the population

 

resided in the colonia for ﬁve years or more (INEGI, 2000, 2002).

The 2000 census for the city of Oaxaca reported a working population of about
53%; the corresponding ﬁgure for San Juan was 40% (INEGI, 2000, 2002). About
18% of the working population declared household activities as a primary occupation
compared to 17% in 2000 (INEGI, 1990, 2000). This sector represents mainly
women who, despite not having a formal job, do various activities to bring resources
to support the family. Examples include tortilla making or vending combined with
household chores. About 33% of the Oaxaca population work as employees or in
industry, and 40% works in the service sector (INEGI, 2000).

Data on average family income in 1990 indicated that less than one-half of
families (40%) received between one and two minimum wages (minimum salary),
25% received less than one minimum wage, and one-third (33%) reported more the
two minimum wages. In the 2000 census, about 15% of the working population in

the San Juan Chapultepec area received less than one minimum wage, 31% received

58

between one and two minimum wages, and only 23% reported income between two
and ﬁve minimum wages (INEGI, 2002). Although the data indicate some
improvement, the ﬁgures for 2000 still indicate generally limited resources to satisfy
basic human needs.

A survey of 3360 households in the city of Oaxaca in the 1990 census (INEGI,
1993) indicated the following house characteristics. Roofs were made primarily of
laminated cardboard (35%) and concrete (42%); walls were made of brick (57%),
adobe (20%), and wood (4%); and almost 65% of houses had cement ﬂoors.
Corresponding estimates for a survey of 3570 households in the San Juan area in 2000
(INEGI, 2000, 2002) indicated generally improved living conditions. Walls were made
largely of concrete, cement or bricks (70%), while only 30% had light and/or
precarious building materials for walls; about 81% of the houses had cement ﬂoors.

Sanitary conditions represented by potable water, sewage facilities and waste
disposal indicated more favorable living conditions in 2000. Only 14% of houses had
no sewage, while 76% were connected to street sewage and 6% to septic tanks. About
86% of houses had access to potable water (INEGI, 2000, 2002). There also was a
regular service of municipal trucks to collect waste on a daily basis, although service is
less frequent in the higher sections (i.e., near to top of the hill) of the oolorria. Public
transportation is provided by regular bus and taxis service to Oaxaca city.

Public transportation is provided by regular bus service to the central areas of
the city of Oaxaca. Taxis are also available on a regular basis. The buses presently
reach the mos near the tops of the hills, although many individuals climb rather
steep paths to negotiate the hilly environment of the ool_or_iia.

In the mid-19703, the most common health problems in San Juan showed
seasonal variation (Graedon, 1976). There was a high prevalence of gastrointestinal
problems from March to April, which was attributed to water and environmental

contamination. More recent data from the health center indicate a high prevalence of

59

respiratory and gastrointestinal infections as the main problems between 1995 and 1999
(Martinez-Morales, 1999). More speciﬁc information is limited to households that are
located in the vicinity of the health center, which is located adjacent to the agencia

municipal. It reaches less than 1000 inhabitants of the colonia. The attending

 

physician and medical student in training also indicated the lack of accurate
demographic and health data for this speciﬁc sector of the city (San Juan).
Although most streets are paved, there are many unpaved roads, particularly as

one moves up the hillside. In addition, sanitary deﬁciencies increase as the barrios

 

progress greater distances from the center. A physician and two nurses at a health

center provide basic attention on daily basis, 8 hours a day. The closest hospital is

 

about 5 km away from the colonia, but there are some private services provided by .
general practitioners and a private hospital. Given the proximity of San Juan to
downtown Oaxaca, the population has relatively easy access to work opportunities

and services such as health clinics, pharmacies, stores and markets.

Overview of Conditions in the Rural and Urban Communities

Indicators of social, economic, educational and living conditions in the two
communities which are the basis of this study are summarized in Table 3.2. The
information is derived from the 2000 national census (INEGI, 2002). Conditions in the
rural community related to health and sanitation are generally inferior to those in the
urban community. Rural households also have relatively fewer appliances with the
difference most marked for refrigerators. This obviously has implications for the
storage of foods. About one-half of the economically active population in the rural
community has no regular wages, whereas about two-thirds of the economically active
population in the urban community receives between 1 and 5 minimum wages. The
urban and rural communities do not differ in the prevalence of literacy/illiteracy, but

urban adults have slightly more years of schooling.

60

The characteristics of the urban community, San Juan, are generally similar to
those for the city of Oaxaca, and are better than those for the state of Oaxaca as a
whole. The characteristics of the rural community, Santo Tomas, vary compared to
those for the state of Oaxaca. Indicators of health (sanitation, health insurance
coverage) are relatively less available in Santo Tomas, and proportionally more
economically active individuals receive no wages in Santo Tomas compared to the
state as a whole. In contrast, proportionally more individuals 15+ years of age in

Santo Tomas are literate compared to those in the state of Oaxaca.

Subjects

Study subjects were children enrolled in the primary school in each community.
Attendance in primary (elementary) school is required in Mexico, and the focus of
the study was children enrolled in school. The project was developed within the
activities of the general project: “Secular change in size, strength and motor ﬁtness in
the Valley of Oaxaca, Mexico,” with Robert M. Malina as principal investigator
(Malina 1998). The project was approved by the University Committee for Research
Involving Human Subjects at Michigan State University (Appendix 1). After initial
contacts with each community, permission for the study was granted bylocal
authorities and school ofﬁcials of each community. All activities were supervised by
minicipal and school authorities in both communities.

There was a very good relationship with the presidente municipal and other
members of the municipio’s administration in the rural community. The research
team contributed some books to the local library and some medicines to the health
center. In addition, the team also assisted the administration in preparing a document
about the village history. The latter was based on interviews with the oldest
individuals in the community and discussions with archeologists who worked in the

area. The document is presently available in the community library.

61

Informed parental consent in both communities was obtained after meeting with
the parents at the respective schools. At these meetings, the purpose of the study was
explained and a consent statement was distributed and read to the parents. Some of
the parents were not able to read the approved form. Only those children whose
parents provided informed consent to participate in the study were included.

Self-assent was obtained from older school children (10 years of age and older).
The statement of participation in the study was read to them and they were informed
that they could decide if they wanted to participate in the study and that they could
withdraw from the study at any time.

The rural sample was comprised of the children enrolled at the primary school
in Santo Tomas Mazaltepec. The school program included morning (8 a.rn. to 12:30
pm, with a one-half hour break 10-10:30 am.) and afternoon (1:30 pm. to 6 pm,
with a one-half hour break, 4-4:30 pm.) sessions. Children enrolled in both
programs were included in the sample. The break is used in both sessions for children
to get a meal. For the morning school, the meal was breakfast, since children
generally leave home without eating a meal. For the evening session, the meal
corresponded to lunch. A total of 367 children, 180 boys and 187 girls, in the 1“
through 6‘“ grades was measured and tested in the Fall 1999 and Spring 2000.
According the school records, there were 372 children enrolled at the beginning of
the school year, but several dropped out before the study was started.

The urban sample was drawn from one of three primary schools in San Juan
Chapultepec. It was the same school studied previously (Malina et al., 1976). In
contrast to Santo Tomas, San Juan had only a morning session. The duration of the
session for the urban children was the same as in the rural community. A total of 341
subjects, 175 boys and 161 girls, in the 1“ through 6‘“ grades was measured and
tested in the Fall 1999 and Spring 2000. Note that the total enrollment in the school

at the start of the academic year was 342 children and one child was not in

62

attendance during the time of the survey. Hence, the present sample represents the
entire student body.

Chronological age of each child was based on the date of measurement and birth
dates obtained from school records and corroborated by parents and teachers if
necessary. When birth certiﬁcates were not available for children in Santo Tomas, dates
were obtained from the municipal records in the community or the archives in Etla.
Children were grouped into whole year age categories, i.e., 6.0 to 6.99 deﬁned the 6
year age group, and so on. The distribution of subjects measured during the survey of
each community by age group and sex is indicated in Table 3.3. The total sample
surveyed was 708 school children 6 to 15 years of age, 367 (180 males, 187 females) in

the rural community) and 341 (175 males, 166 females) in the urban community.

Data Collection Procedures

Anthropometric, menarcheal status and physical ﬁtness data were collected at
the respective schools during regular school hours in both communities. In addition,
an activity and dietary questionnaire was administered in children in grades 4, 5 and
6. The data collection forms are given in Appendix II. The speciﬁc protocols for

each type of data are described subsequently.

Anthropometg

A battery of anthropometric dimensions was selected to provide information on
growth (size attained) and nutritional status. The growth status of children is
universally accepted as an indicator of the overall health and nutritional status of a
community (Waterlow et al., 1977).

Height and weight provide an indication of overall body size and in the form of the
body mass index (BMI, wt/htz), provides an indication of underweight and overweight.

Sitting height in conjunction with standing height provide an indication of segment

63

lengths and proportions. Skeletal breadths and limb circumferences provide an indication
of skeletal robustness and relative muscularity, and skinfold thicknesses provide an
estimate of subcutaneous fatness and relative fat distribution (Malina, 1995a).

Measurements were taken following the procedures described in Lohman et a1.
(1988; see also Malina 1995a). Bilateral dimensions were taken on the left side (as
were measurements in earlier studies done in Oaxaca). Anthropometric data were
collected by MEPR. Six students of physical anthropology, who were speciﬁcally
selected and trained for the study by the principal investigator, assisted in recording,
ﬁtness testing and anthropometry of adults (which is part of the broader study and is
not considered in this study). The students were enrolled in the Escuela Nacional de
Antropologia e Historia (ENAH) in Mexico, D.F.

Anthropometric dimensions were taken with calibrated instruments. The
protocol was the same as used in the 1968 and 1978 surveys in Santo Tomas and the
1972 survey in San Juan. Weight was measured with a portable ﬁeld unit
(HealthOMeter) that was scaled to 100 grams. Stature and sitting height were
measured with a GPM (Martin type) ﬁeld anthropometer (Pﬁster Import-Export, Inc.,
Carlstadt, NJ), while skeletal breadths on the trunk were measured with the upper
segment of the ﬁeld anthropometer used as a sliding caliper. Skeletal breadths on the
extremities were measured with a small sliding caliper (Martin type, 25 cm; Pﬁster
Import-Export, Inc.). Circumferences were measured with a retractable ﬁber glass
tape (non-stretchable, Grafco), and skinfolds were measured with a Lange caliper
(Cambridge Scientifc Industries, Cambridge, MD). The skinfold caliper was
regularly calibrated relative to the standardized wedge provided by the manufacturer.

Body mass (weight) was measured in kilograms using a portable scale and
recorded to the nearest 100 grams. Weight was measured without shoes, but the
children wore light clothing with all accessories removed (sweaters, sweatshirts,

jackets, etc.).

64

mtg}; (standing height) was measured with the child standing erect posture,
without shoes and with body weight evenly distributed between both feet. The heels
were placed together and the arms were hanging relaxed at the sides. Height is the
distance from the ﬂoor to the top of the head positioned in the Frankfort horizontal
plane. Measurements were recorded to the nearest 0.1 centimeter.

Sitting height corresponds to the distance from the table (sitting surface) to the
highest point at the top of the head (vertex). The individual sat erect on the table
with the knees hanging freely and the hands positioned on the thighs. Sitting height
was measured to the nearest 0.1 cm.

Biacromial breadth was measured as the distance between the left and right
acromial processes of the scapulae with application of ﬁrm pressure. The
measurement was taken from the rear and was recorded to the nearest 0.1 cm.

Bicristal breadth was measured as the distance between the most lateral points
of iliac crests with application of ﬁrm pressure. The measurement was taken from
the rear and was recorded to the nearest 0.1 cm.

Bicondylar breadth was measured as the distance across the most medial and
most lateral points of the femoral condyles. The individual was seated with the knee
ﬂexed 90°. The measurement was recorded to the nearest 0.1 cm.

Biepicondylar breadth was measured as the distance between the epicondyles of
the humerus with the elbow ﬂexed 90°. The measurement was recorded to the nearest
0.1 cm.

Limb circumferonces. Three limb circumferences were measured and recorded
to the nearest 0.1 cm.

Relaxed arm circumferenco was measured at the level midway between the
olecranon and acromial processes with the arm handing loosely at the side. The tape
was placed in the horizontal position in contact with the skin but without

compression of the underlying soft tissues.

65

F lexed arm circumference was taken at the same level as relaxed arm
circumference, but the arm was ﬂexed to a right angle at the elbow.

Calf circumference was measured as the maximum circumference of the calf
with the subject in a standing position and body weight evenly distributed between
both legs. The measuring tape was placed in a horizontal plane in contact with the
skin but without compressing the soft tissues.

Four skinfolds were measured to the nearest 0.5 mm using a Lange skinfold
caliper (as was used in the earlier studies in Oaxaca). A double fold of skin and
underlying soft tissue was raised with the thumb and index ﬁnger of the left hand
about one cm above the speciﬁc site for each fold and the caliper was applied to the
site.

Triceps skinfold was measured on the back of the arm over the triceps muscle
at the same level as relaxed arm circumference.

Subscapular skinfold was measured on the back immediately beneath the
inferior angle of the scapula following the natural cleavage line of the skin.

Suprailiac skinfold was measured immediately above the iliac crest in the
midaxillary line.

Calf skinfold was measured on the medial aspects of the calf at the same level
as calf circumference.

During the ﬁeld phase of the study with the school children, every tenth child
was measured independently by MEPR on a second occasion to estimate intra-
observer measurement variability. The replicates were taken about one month after
the initial measurements (hence, there is the potential for a growth factor in the
interpretation of measurement variability). The technical error of measurement (3:)
was calculated as follows:

a, = VXdZ/ZN,

66

the square root of the sum of differences between replicate measurements squared
divided by twice the number of replicates (Malina, 1995a). lntra-observer technical
errors of measurement for the present study are summarized in Table 3.4. They
compare favorably with errors based on within day replicates from an earlier survey in
the rural community (Table 3.3) and with corresponding intra- and inter-observer
technical errors in several national health surveys in the United States (Malina, 1995a).

The basic anthropometric dimensions were used to derive several additional
variables:

1. The body mass index (BMI) was calculated as weight (kg) divided by height
(m) squared (kg/m2). It is used primarily as an indicator of overweight, but is also
used as an indicator of underweight in developing countries.

2. The sitting height/standing height ratio expresses relative sitting height and
provides an estimate of the relative contribution of the trunk or lower extremities to
stature. The ratio was calculated as sitting height/standing height X 100.

3. Estimated leg (subischial length) was calculated as standing height minus
sitting height.

4. Estimated mid-arm muscle circumference and area were derived from relaxed
arm circumference (Ca) and the triceps skinfold (St) as follows (Malina, 1995a):

Upper arm muscle (cm) = Ca - (1: St)

where Ca is arm circumference and St is the triceps skinfold (cm).

5. The trunk-extremity ratio (TER) was used as an estimate of relative subcutaneous
fat distribution. The sum of the two trunk skinfolds (subscapular and suprailiac) was

divided by the sum of the two extremity skinfolds (triceps and medial calf).

Age at Menarche

All girls were interviewed on menarcheal status by MEPR or a female assistant.

They were ﬁrst asked in Spanish and with culturally appropriate terminology whether

67

or not menarche had occurred (status quo method, Malina and Bouchard, 1991). In
the case of post-menarcheal girls, they were also asked to recall the age at which

menarche was attained. Prompts were used to facilitate the recall process.

Physical Fitness

Physical ﬁtness items included a combination of motor-and-health-related
tasks. Four tasks were used in an earlier study in Santo Tomas - right and left grip
strength, 35 yard dash, and standing long jump (Malina and Buschang, 1985).
Several additional tasks were added for the current study.

Static grip strength of the right and left hand was measured with a Stoelting
adjustable dynamometer. The subject held the dynamometer in the line with the
forearm at the level of the thigh. Children were instructed to squeeze the
dynamometer as vigorously as possible so as to exert maximum force. Three trials
were administered for each hand, the protocol alternating trials between hands. The
best trial with each hand was retained for the analysis (Malina and Buschang, 1985).

The 35-yard dash (32.3 meters), an indicator of running speed, was measured as
the time elapsed from the starting signal to crossing the finish line. The children ran
on a ﬂat concrete surface on the respective school grounds. The elapsed time was
recorded to the 0.1 second. Two trials were administered, and the better of the two
was retained for the analysis. A sufﬁcient rest period between trials was included in
the protocol (Malina and Buschang, 1985).

The standing long jump, a measure of power, was measured as the distance
from the take-off line to the point where the heels touched the ground. The distance
was measured to the nearest cm. Three trials were administered and the best of the
three was retained for the analysis (Malina and Buschang, 1985).

The 12 minute run/walk was used as a measure of cardiorespiratory ﬁtness.

The subjects ran or walked for 12 minutes in an area at the urban school or the

68

central plaza of the rural community, which was previously laid out with posts
marking the limits and distance covered. The number of laps was counted by the
research assistants. A warm-up and cool-down was provided done before and after
the test, respectively. Participants ran in groups of about ﬁve. The distance run was
recorded to the nearest meter by the research assistants. After testing several ﬁrst
grade children, it was noted that younger children had a difﬁcult time trying to
complete the 12 minutes walk/run. Therefore, the test was modiﬁed for children in
the younger ages, corresponding to children at the 1“ to 3‘°grades. The walk/run time
was reduced from 12 to 8 minutes. Only one trial was administered and the children
were verbally encouraged throughout the test to complete the task.

The 't-an -reach, an indicator of lower back and upper thigh ﬂexiblity, was
measured as follows. Subjects were permitted to warm-up before the test by
performing slow stretching movements. The subject removed his/her shoes and was
seated at the test apparatus with the legs fully extended. The heels were
approximately shoulder width apart and the feet were ﬂat against the end board of the
apparatus. The subjects were instructed to extend the arms forward as far as possible
with the hands placed on t0p of each other. The subject leaned forward extending the
ﬁnger tips, with palms facing downward, as far along the ruler as possible without
jerking or bouncing. This effort pushed a sliding marker along the scale. The child
stretched forward along the top of the box four times. On the fourth attempt, he/she
held the stretch for at least one second. The score was the farthest point reached on
the last stretch, which was recorded to the nearest centimeter (Safrit, 1995). Three
trials were recorded and the best of the three was retained for the analysis.

S_it_-up_s, a measure of abdominal strength and endurance, were measured as
follows. The subject was in a supine position with the knees bent at right angles and
the feet approximately shoulder width apart. The hands were placed at the side of the

head with the ﬁngers over the ears and with the elbows pointed toward knees. The

69

hands and elbows had to be maintained in this position for the entire duration of the
test. The participant’s ankles were held throughout the test by the appraiser to ensure
that heels were in constant contact with the mat. The subject was required to sit up,
touch the knees with the elbows, and return to the starting positions (shoulder touching
the mat). Each subject performed as many sit ups as possible within 30 seconds.
Subjects were permitted to pause for rest whenever necessary. Clear instructions were
given. Bouncing “was not allowed and the subject’s buttocks had to remain in contact
with the mat. In curling down after the sit up, the lower back had to be in contact with

the mat before the upper back and shoulders touched. One trial was given.

Test Validity and Reliability

Grip strength, standing long jump and 35-yard dash are indicators of static
strength, power (explosive strength) and running speed, respectively. The are
commonly used indicators of performance-related physical ﬁtness (Malina, 1995b).
The tests require all out effort, and have face validity and good reliability
(Fleishman, 1964; Simons et al., 1969).

The sit-and-reach, timed sit-ups and distance run are indicators of lower back and
hamstring ﬂexibility, abdominal strength and endurance, and cardiovascular endurance
(aerobic capacity), respectively. They are indicators of health-related physical ﬁtness
(American Alliance for Health, Physical Education, Recreation and Dance, 1980). The
validity of the sit-and-reach as an indicator of back ﬂexibility is limited; the test is
apparently a more valid estimate of hamstring ﬂexibility. In contrast, the sit-and-reach
has high reliability (Plowman and Corbin, 1994). The validity of sit-ups as a measure
of abdominal strength and endurance is uncertain due to the lack of an agreed upon
criterion measure. However, the test has moderate to moderate high reliability
(Plowman and Corbin, 1994). Distance runs have moderate validity as indicators of

aerobic capacity and moderate to high reliability (Cureton, 1994).

70

For ﬁtness items with more than one trial in the present study (right and left grip
strength, dash, standing long jump, sit and reach), repeated measures ANCOVA was used
to estimated within day reliabilities (intraclass correlations). Results are summarized in
Table 3.5. The intraclass correlations range from 0.85 to 0.95 and indicate good within
day reliability of these ﬁtness measures. Correlations were also were also calculated
between ﬁrst vs second trial, ﬁrst vs third trial, best vs second best, second best vs third
best, etc. The average of the correlations are summarized in Table 3.6. With two
exceptions (r=0.71 and 0.77 for the dash in boys, all correlations range between 0.81 and

0.93, and indicate acceptable levels of reliability for group comparisons.

Activity and Diet Information for Older Children

Measuring habitual physical activity and recording dietary intake of children is a
difficult task, especially in ﬁeld settings where literacy levels vary and concepts of time
and amounts may not be the same as in western cultures. To obtain an estimate of
physical activities and foods consumed by the school children, students in the 4‘“ through
6‘“ grades were asked to complete an activity questionnaire and to write down a list of the
foods that they ate at each meal the day before. The data provide a general description of
activities and foods consumed by children in the upper primary school grades.

The activity questionnaire was administered in the classroom setting. The
questions were read aloud for the group, and the children were given time to write
their answers. The assistants walked around the classroom to provide assistance as
needed, largely in the context of answering speciﬁc questions and providing
explanations. The assistants collected the questionnaires, checked the responses, and
clariﬁed answers with children if necessary.

The children were asked to describe their daily routines and kinds of activities
they did with their parents, caregivers, siblings and peers, including play activities

during school and free time and work chores. The children were also asked to

71

describe their activities during free time, speciﬁc games and/or sport activities,
television viewing, and household chores.

To estimate diet, a short term 24-hour recall was used. The children were asked
to indicate the different foods consumed within the past 24 hours. Amounts were not
requested. A similar protocol was used in earlier studies (Peﬁa et al., 1995). The
information was compared to the list of foods consumed at the household level
during interview. In previous studies in Oaxaca, the communities were characterized
as having a relatively limited diet with a relatively small number of foods, according
to previous surveys. A basic list derived from the earlier studies (Amdurer, 1976;
Peﬁa et al, 1995) was used with the children and households.

The purpose of the activity and dietary assessments of older school children
was to provide an indication of habitual activities and foods consumed. They are a
complement to the anthropometric and ﬁtness data, and provide background
information on dietary intake and activity behaviors of primary school children in the
urban and rural settings. The data are presented in a descriptive manner as

community- and sex-speciﬁc frequencies and percentages.

Preparatory Activities for the Field

Prior to going into the ﬁeld, preparatory activities were undertaken in three
phases. First, potential ﬁeld assistants (students enrolled in Escuela Nacional de
Antropologia e Historia, ENAH) in Mexico City were identiﬁed and interviewed by
the co-principal investigator and ﬁeld coordinator (MEPR). Six assistants were
eventually selected. All were students of physical anthropology and had previous
experience with anthropometry.

Second, a working session was conducted in the Anthropometry Laboratory of
ENAH. This session provided more detailed information about the project and

speciﬁc training about the ﬁeld protocols for anthropometry, physical ﬁtness testing,

72

and interviewing school children. A preliminary activity questionnaire was
developed during this session. This session took about one week.

Third, standardizing sessions were conducted for anthropometry and ﬁtness
testing. For the former, the speciﬁc dimensions were described and demonstrated
and then the assistants practiced taking the measurements on each other, and also on
other adults and children who visited the laboratory at ENAH. All anthropometric
dimensions were taken under the supervision of the ﬁeld coordinator (MEPR). The
protocol for the administration of the hand grip strength tests was also standardized
at this time. This phase took about two weeks.

After the anthropometric phase, the second part of the standardizing process
concerned physical ﬁtness testing. The assistants ﬁrst work in the laboratory to
familiarize themselves with the tests, equipment, test procedures and sequence,
instructions for children, and recording. The tests were performed initially by the
assistants outdoors on a basketball court at ENAH. Then, the tests were administered
to a group of six children, 8-12 years of age. This phase took about one week.

The ﬁnal phase of the standardization process involved the preparation and
ﬁeld testing of the activity questionnaire. The development of the activity
questionnaire was based on the following guidelines: (1) What activities do school
children do in three different settings: at home, at school, and outside of school; and
in the context of several social interactions - by themselves, with peers, with
teachers, with adults (relatives, caretakers, others)? (2) What are the children’s
responsibilities to their respective households, i.e., work-related activities for the
family - food preparation, animal care, wood gathering, ﬁeld activities, and others, as
well as family business activities, e.g., tortilla sales. (3) What do school children do
during after school time (and on weekends), with a speciﬁc emphasis on physical
activities related to work-related chores and leisure? (4) What kind of games and

organized activities are they involved in and what is the level of involvement? The

73

students administered the activity questionnaire to each other and then to several
other students at ENAH. After group discussion and evaluation, modiﬁcations were
made as needed. This took about one week.

After the standardization sessions, a pilot study was conducted. The
instruments were tested on a group of urban school children in Cuernavaca, Morelos.
The entire battery, including anthropometry, physical ﬁtness tests and activity
questionnaire, was applied to a group of children. Subsequently, adjustments and/or
modiﬁcations were made as needed, and the recording forms were ﬁnalized. Further
adjustments were made in the ﬁeld as needed, e.g., modifying the 12 minute run to an

8 minute run to accommodate children in grades 1 through 3.

Statistical analysis

Given the small number of children 14 and 15 years of age (6 in the rural
community and 2 in the urban community), they were not retained for the analyses.
Thus, the analysis is limited to school children 6 through 13 years of age. Sample
sizes by age group and sex, and means and standard deviations for chronological age
for the rural and urban school children retained for the analyses are indicated in Table
3.7. The total sample thus includes 700 school children 6 to 13 years of age, 361
from the rural community (177 males, 184 females) and 339 from the urban
community (173 males, 166 females). By sex, the overall sample includes 350 males
(177 rural, 173 urban) and 350 females (184 rural, 166 urban).

The analysis followed several directions. First, descriptive statistics (means,
standard deviations and medians (where appropriate) for all variables were calculated
by age group and sex in each community. Second, to establish the current growth
status of the rural and urban children, mean heights, weights, and BMIs were plotted
relative to the new United States growth charts or reference data (Centers for Disease

Control and Prevention, 2000). Third, the descriptive statistics for all variables were

74

plotted by age to illustrate general trends in comparisons of the rural and urban males
and females, respectively, in the anthropometric (measured and derived) and physical
ﬁtness characteristics. Given the small numbers among 12 and 13 years old children,
graphic presentation of the data was limited to children 6 through 11 years of age.

The subsequent analyses focused on the speciﬁc study questions.

1. How do current samples of urban and rural school children 6-12 years of age in
southern Mexico compare in growth status?

Analysis of covariance (ANCOVA) with age as the covariate was used to test
the signiﬁcance of differences in height, weight and other anthropometric indicators
between urban and rural school children. The data were analyzed in two age groups
separately for each sex: 6-9 and 10-13 years. As noted earlier, numbers of older
children (14+ years) were too limited for the analysis. The samples were combined
into two age groups to approximate earlier (6-9 years) and later (10-13) ages of
middle childhood. These groupings were valid from two perspectives. First, the
younger age group (6-9) is probably prepubertal. All girls 6-9 years were pre-
menarcheal. This is also an age group in which children are nearing mature
movement patterns for fundamental motor skills. Second, the older age group (10-
13) probably includes children who have begun the transition into adolescence,
which inﬂuences body dimensions and physical ﬁtness. Six rural and 5 urban girls
11-13 years of age were already post-menarcheal (Table 3.8). A level of p<0.05 was
accepted.

The following hypothesis was tested in the context of this research question:
Urban school children have better growth status assessed with height, weight and
other anthropometric indicators than rural school children. This hypothesis was

deemed reasonable based on earlier studies in Oaxaca and in other areas of Mexico.

75

2. How do current samples of urban and rural school children 6-12 years of age in
southern Mexico compare in physical ﬁtness?

Analysis of covariance (ANCOVA) with age as the covariate was used to test
the signiﬁcance of differences in six tests of physical ﬁtness between urban and rural
school children. The raw scores of each test were used in the comparisons. The data
were analyzed in two age groups separately for each sex: 6-9 and 10-13 years (see
above). A level of p<0.05 was accepted.

The following hypothesis was tested in the context of this research question:
Urban school children perform better on tests of physical ﬁtness than rural school
children. As noted in Chapter 2, data comparing the physical ﬁtness of urban and
rural children are limited. The available data, however, suggest generally better

levels of ﬁtness in urban samples.

3. How do current samples of urban and rural school children in southern Mexico
compare in the estimated prevalence of growth stunting and wasting?

Growth stunting was estimated using the criteria of the World Health
Organization (WHO, 1995), in which stunting is deﬁned as low height-for-age
relative to internationally acceptable reference data. A height below two standard
deviations of age- and sex-speciﬁc reference values is classiﬁed as stunted. Heights
of individual children were converted to z-scores using the protocol and reference
values of the new United States Growth charts (Centers for Disease Control and
Prevention, 2000). A z-score below —2.0 was deﬁned as stunting. Note that the
original recommendation of the WHO was based on the earlier United States Growth
Charts (Hamill et al., 1977).

The sex-speciﬁc prevalence (and 95% conﬁdence intervals) for growth stunting
was calculated for each age group (6-9, 10-13 years) and the total sample (6-13

years). Sex-speciﬁc comparisons of the prevalence of stunting in the two age groups

76

and the total sample of urban and rural children were tested with the chi-square
statistic.

Many developing areas of the world include an epidemiological paradox, a
continued presence of undemutrtion in the face of an increasing prevalence of
overweight/obesity. Wasting is a form of undemutrition that indicates low weight-
for-height (World Health Organization, 1995). Wasting was deﬁned as a BMI below
the 5‘“ percentiles of age- and sex-speciﬁc reference data for the United States
(Centers for Disease Control and Prevention, 2000).

The sex-speciﬁc prevalence (and 95% conﬁdence intervals) for wasting was
calculated for each age group (6-9, 10-13 years) and the total sample (6-13 years).
Sex-speciﬁc comparisons of the prevalence of wasting in the two age groups and the
total sample of urban and rural children were tested with the chi-square statistic.

The following hypothesis was tested in the context of this research question:
Rural school children have a higher prevalence of growth stunting and wasting than

urban school children.

4. How do the current samples of urban and rural school children in southern Mexico
compare in the estimated prevalence of overweight and obesity?

Overweight was deﬁned relative to the internationally recommended criteria
(cut-off points) based on six national samples (Cole et al., 2000). The recommended
cut-off points for the international criteria are based on pooled data from six
nationally representative cross-sectional growth surveys — Brazil, Great Britain,
Hong Kong, the Netherlands, Singapore, and the United States (excluding the most
recent national health examination survey, 1988-1994, NHANES III). In establishing
the cut-off points, a BMI of 25 kg/m2 at 18 years of age was considered overweight
and a BMI of 30kg/m2 at 18 years of age was considered obese. Curves were then

mathematically ﬁt to the pooled BMI data from 2 years of age on so that they passed

77

through a BMI of 25 kg/m2 and 30 kg/m2 at 18 years of age (retro-ﬁtting). The
values at each half year from 2 to 18 years of age are the respective cut-off points for
overweight and obesity (Cole et al., 2000).

The sex-speciﬁc prevalence (and 95% conﬁdence intervals) of overweight and
obesity was estimated for each age group (6-9, 10-13 years) and total sample (6-13
years). The sex-speciﬁc comparison of the prevalences of overweight and obesity in
the two age groups and the total sample of urban and rural children was tested with
the chi-square statistic. The following hypothesis was tested in the context of this
research question: Urban school children have a higher prevalence of overweight and

obesity than rural school children.

The reported daily activities and foods consumed by the 4‘“, 5‘“ and 6‘“ grade
children in the urban and rural communities were summarized in frequencies and
percentages. The activities were divided into those related to recreation and those
related to household chores. Time spent viewing television and intensity of
household-related activities was also estimated. The ten most commonly reported
food items for each meal of the day (breakfast - desaﬂno, lunch - comida, dinner -

cena) were listed separately for rural and urban children.

78

Chapter 4

Results

Descriptive statistics by age group and sex in the urban and rural communities
are given in Appendix III, Tables III.1 through 111.14. The data are plotted in Figures
4.1 through 4.25. As noted earlier, the plotted data are limited to ages 6 through 11 due
to small numbers at 12 and 13 years. Results of the analyses of covariance, with age as
the covariate, and age-adjusted means and standard errors are summarized in each of
the following sections dealing with body size, segment lengths and proportions,
skeletal breadths, limb circumferences and estimated muscularity, subcutaneous fatness
and relative fat distribution, and physical ﬁtness. Prevalences and 95% conﬁdence
intervals and results of the chi square analyses for stunting, wasting and overweight in
the two communities are then compared. A descriptive comparison of the recreational

and household activities of 4‘“, 5‘“ and 6‘“ grade children closes the chapter.

Anthropometry

Body Size. The growth status of the sample relative to US. reference values
(Centers for Disease Control and Prevention, 2000; Kuczmarski et al., 2000) is shown
in Figures 4.1 through 4.6. On average, the heights of urban boys and girls fall at or
above the 10‘“ percentiles and approach the 25‘“ percentiles at several ages, whereas the
heights of rural boys and girls ﬂuctuate between the 5‘“ and 10‘“ percentiles (Figures 4.1
and 4.2). Mean weights of urban children of both sexes tend to be above the 25‘“
percentiles of the reference values. In contrast, mean weights of rural boys and girls
are at or below the 25‘“ percentiles (Figures 4.3 and 4.4). The trends for mean heights
and weights suggest elevated weight-for—height in both the urban and rural samples.

This is reﬂected in the BMI, which, on average, falls between the 25‘“ and 75‘“

79

percentiles of the reference data at most ages (Figures 4.5 and 4.6). The urban-rura1
contrast is more apparent among 10-11 year old boys and 6-9 year old girls.

Mean heights, weights and BMIs of the urban and rural samples are illustrated
in Figures 4.7 to 4.9, while results of the ANCOVA, with age as the covariate, are
summarized in Table 4.1. In the two age groups within each sex, urban children are
significantly taller and heavier than rural children. The BMI does not signiﬁcantly
differ between urban and rural males 6-9 years and females 10-13 years, but is
signiﬁcantly higher in urban than in rural females 6-9 years and males 10-13 years.

Sogment Lengtbs and Proportions. Mean sitting heights and leg lengths of urban
and rural children are illustrated in Figure 4.10, while mean sitting height/standing height
ratios are shown in Figure 4.11. On average, sitting height and leg length are
signiﬁcantly longer in urban than in rural children of both sexes in each age group (Table
4.1). This reﬂects the greater standing height of urban children. Although absolute sizes
of the two components of height are larger in the urban sample, there are no urban-rural
differences in relative proportions. This is shown in the ratio of sitting height to standing
height (Figure 4.11). The ratio does not differ between urban and rural children.

Skeletal Breadths. Age-for-age, the two skeletal breadths taken on the trunk
(biacromial and bicristal breadths) are, on average, larger in urban than in rural
children within each sex (Figure 4.12). Shoulder (biacromial) and hip (bicristal)
breadths are signiﬁcantly larger in urban than in rural boys and girls in each age group
(Table 4.2). This likely reﬂects the larger overall size of the urban sample. In contrast
to skeletal breadths of the trunk, the skeletal breadths taken on the extremities
(biepicondylar and bicondylar) do not consistently differ between urban and rural
children (Figure 4.13). Results of the ANCOVA (Table 4.2) indicate that the two
extremity skeletal breadths are signiﬁcantly larger in urban than in rural boys with the
exception of biepicondylar breadth at 6-9 years. Among girls, both extremity breadths

are signiﬁcantly larger in urban than in rural children 6-9 years, but do not differ

80

between urban and rural children 10-13 years. It should be noted, however, that
although the differences between urban and rural children are statistically signiﬁcant in
some cases, the absolute differences in extremity skeletal breadths are quite small.

Limb Circumferences and Estimated Muscularig. Age trends in arm and calf
circumferences are shown in Figure 4.15, while corresponding trends in estimated arm
and calf muscle circumferences are shown in Figure 4.16. Age-adjusted mean
circumferences based on the ANCOVAs (Table 4.2) are generally larger in urban than
in rural children. However, the differences are signiﬁcant only in girls 6-9 years and in
boys 10-13 years. Among boys 6-9 years, arm circumference and estimated midarm
muscle circumference do not differ between the urban and rural samples, whereas calf
and estimated calf muscle circumferences are signiﬁcantly larger in the urban sample.
Among 10-13year old girls, on the other hand, the urban-rural contrasts in arm and calf
circumferences and in estimated muscle circumferences are not signiﬁcant.

Subcutaneous Fat and Relativo Fat Distribution. Age trends in the four skinfold
thicknesses are shown in Figures 4.16 to 4.19, while corresponding data for the sum
of the four skinfold thicknesses and the trunk-extremity ratio are shown in Figures
4.20 and 4.21, respectively. Results of the ANCOVA are summarized in Table 4.3.
The thickness of each skinfold and the sum of the four skinfolds do not differ
between urban and rural boys and girls 6-9 years and between urban and rural girls
10-13 years. On the other hand, urban boys 10-13 years have signiﬁcantly thicker
skinfolds (individual skinfolds and sum of four skinfolds) than rural boys of the same
age. The same trends are apparent in the trunk-extremity ratio, indicating no urban-
rural differences in relative subcutaneous fat distribution (Figure 4.21), with the
exception of urban boys 10-13 years of age have proportionally more subcutaneous
fat on the trunk (higher ratio) than rural boys of the same age.

Hypothesis. Urban school children have better growth status as assessed with

height, weight and other anthropometric indicators of growth than rural school

81

children. This hypothesis was partially supported. Absolute body size (height and
weight), trunk (sitting height) and estimated leg length, skeletal breadths on the trunk
(biacromial and bicristal breadths) are signiﬁcantly larger in urban than in rural school
children. Urban-rural constrasts in skeletal breadths on the extremities (biepicondylar
and bicondylar breadths), limb circumferences, estimated limb muscle circumferences,

and subcutaneous fatness are not consistently signiﬁcant by age group and sex.

Physical Fitness

Comparisons of mean values for right and left grip strength, the sum of right and
left grip strength, and strength per unit body mass are illustrated in Figures 4.22 to 4.25.
Results of the ANCOVA of the urban-rural comparison are summarized in Table 4.4.

Right grip, left grip and the sum of right and left grip strength do not differ
signiﬁcantly between urban and rural boys and girls 6-9 and 10-13 years of age.
However, strength per unit body mass (sum of right and left grip/body weight) is
signiﬁcantly greater in rural girls 6-9 years and in rural boys 10-13 years. On '
average, strength per unit mass is also greater in rural boys 6-9 years and in rural
girls 10-13 years, but the differences are not signiﬁcant.

Age trends for each of the other physical ﬁtness variables (trends are by grade for the
distance run) are illustrated in Figures 4.26 through 4.30. Comparisons of the age-adjusted
means (AN COVA, Table 4.5) indicate several trends by age group, although the
signiﬁcance of the differences is not consistent across items and age groups. Among
children 6-9 years of age, urban boys and girls perform, on average, better in the sit-and-
reach (p<0.01 males, NS females), sit-ups (p<0.001 males and females), and standing long
jump (p<0.001 males and females), whereas rural boys and girls perform, on average, better
in the dash (NS males, p<0.05 females). The same trends are evident in children 10-13
years of age. On average, urban children perform better in the sit-and-reach (NS males,

p<0.01 females), sit-ups (p<0.01 males, p<0.001 females), and standing long jump

82

(p<0.001 males and females). In contrast to the younger age group, urban children 10-13
years of age also perform better, on average, in the dash (p<0.05 males, p<0.01 females).
Performance in the distance run was evaluated by grade (Figure 4.30, Table
4.5). In grades 1-3, rural children of both sexes run signiﬁcantly greater distances in
8 minutes than urban children (p<0.001 males and females). In grades 4-6, rural
boys run a greater distance in 12 minutes than urban boys but the difference is not
signiﬁcant, whereas urban girls run signiﬁcantly farther than rural girls (p<0.05).
Hypothesis. Urban school children perform better on tests of physical ﬁtness
than rural school children. This hypothesis was partially supported. Urban children,
on average, tend to perform better in the sit and reach, sit-ups, standing long jump and
dash (10-13 years only), but results are not consistently signiﬁcant. Rural children 6-9
years perform better in the dash. There are no urban-rural differences in grip strength,
although strength per unit body mass tends to be greater in rural children. Rural
children in grades 1-3 perform better in the distance run. Rural boys in grades 4-6 also
perform better in the distance run, but the difference is not signiﬁcant. On the other

hand, urban girls in grades 4-6 perform signiﬁcantly better in the distance run.

Stunting

The prevalence of growth stunting (and 95% conﬁdence intervals) in the rural
and urban samples is summarized in Table 4.6. Differences are small and not
signiﬁcant between age groups in each community (all x7- are <1.0). On the other hand,
the prevalence of stunting is about two times higher in rural than in urban children.
The trend is consistent in each age group but signiﬁcance levels vary in the older group
due to the smaller samples sizes, 6-9 (males )6 = 7.48, p<0.01; females x2 = 6.45,
p=0.01) and 10-13 years (males )6 = 3.27, p=0.07; females xz = 2.83, p=0.09). Across
the total age range, 6-13 years, the rural-urban difference in the prevalence of stunting

is signiﬁcant in both boys (7(2 = 10.62, p<0.01) and girls (x2 = 9.26, p<0.01).

83

Hypothesis. Rural school children have a higher prevalence of growth stunting

than urban school children. This hypothesis was supported.

Wasting
In contrast to growth stunting, wasting is relatively rare among the urban and
rural school children in this study (Table 4.7). The estimated prevalence is about 2%
in rural children and 1% in urban children, and there is no sex difference. The urban-
rural difference is not signiﬁcant (boys, x2=0.63, NS; girls, x2=0.49, NS).
Hypothesis. Rural school children have a higher prevalence of wasting than

urban school children. This hypothesis was not supported.

Overweight and Obesity

The prevalence (and 95% conﬁdence intervals) of overweight and obesity,
based on the internationally recommended criteria or cut-off values (Cole et al.,
2000) are summarized in Tables 4.8 and 4.9 for boys and girls, respectively. Across
the entire age range (6-13 years), the prevalence of overweight is greater in urban
than in rural boys (11% vs 5%, respectively, x2 = 4.49, p<0.05) and girls (14% vs 8%,
respectively, x2 = 4.43, p<0.05). The prevalence of overweight is especially higher in
urban (14%) than in rural (3%) boys 10-13 years of age (x2 = 5.70, p<0.05). Among
boys 6-9 years, the urban-rural contrast in the prevalence of overweight is smaller,
9% vs 6%, respectively ()6 = 0.68, NS). The opposite trend is apparent among girls.
The prevalence of overweight is higher in urban than in rural girls 6-9 years of age,
16% vs 7%, respectively (x2 = 4.35, p<0.05). Corresponding percentages for urban
and rural girls 10-13 years of age are 12% and 8%, respectively (x2 = 0.47, NS).

In contrast to overweight, the prevalence of obesity in the urban and rural samples is
low, with the exception of urban boys 10-13 years of age. Among 6-9 year old children,

only 2 urban boys and 2 rural boys are classiﬁed as obese (x2 = 0.003, NS), whereas

84

among 10-13 year old children, 5 urban boys (8%) and no rural boys are classiﬁed as
obese (x2 = 6.00, p<0.05). Among girls, only 2 rural girls (one in each age group) and 4
urban girls (2 in each age group) are classiﬁed as obese (x2 = 0.52, NS; )6 = 0.62, NS).
Hypothesis. Urban school children have a higher prevalence of overweight and
obesity than rural school children. This hypothesis was partially supported. The
prevalence of overweight is signiﬁcantly greater in urban than in rural children,
speciﬁcally when the data are considered across the entire age span, 6-13 years. Within
ages groups 6-9 and 10-13 years, the prevalence is greater in urban children, but the
results are not consistently signiﬁcant. The prevalence of obesity in urban and rural

school children is low, and is signiﬁcantly greater only in urban boys 10-13 years.

Activities of 4‘“, 5‘“, and 6‘“ Grade Children

Self-reported daily activities were obtained from children in the 4‘“, 5‘“ and 6‘“
grades. A structured questionnaire was used. The activities were divided into those
classiﬁed as recreational and those related to household chores. Time spent viewing
television and intensity of household-related activities was also estimated.

Household Activities. Household activities of urban and rural school children
are summarized in Table 14.10. Overall, rural boys report least involvement in
house-related activities. About two-thirds of urban boys and urban and rural girls
report house cleaning chores (62-67%) in contrast to 42% of rural boys. Urban boys
and urban and rural girls also report making the bed (26-33%) compared to only 12%
of rural boys. Urban (52%) and rural (60%) girls report cleaning dishes than urban
(23%) and rural (1%) boys. In contrast to urban girls (12%), more rural girls (25%)
report doing laundry. Few boys (3-4%) report doing laundry.

There are major differences between urban and rural children in food- and
animal-related activities. Relatively few urban children, 2% of boys and 6% of girls,

report involvement in cooking. More rural girls than rural boys report involvement in

85

food-related activities. About 64% of rural girls report activities related to the making
of tortillas compared to 13% of rural boys, and 14% of rural girls report cooking
compared to no rura1 boys. On the other hand, more rural boys report gathering wood
(13%) and getting water (12%) than rural girls (6% report getting water).

Rural children, speciﬁcally boys, report daily involvement in animal-related
activities, caring for animals (70%) and getting animal feed from the pasture (69%).
Smaller percentages of girls report these activities, 8% and 9%, respectively. Small
percentages of urban children report daily care for pets, 8% boys and 3% girls.

Small percentages of rural boys (4%) and girls (2%) report involvement in
farming activities, most often described as clearing ground. More rura1 girls (12%)
than rural boys (4%) reported assisting with a family business, primarily selling
tortillas. Rural and urban girls also report more involvement in caring for siblings
than rural and urban boys.

Recreational Activities. Recreational activities are summarized in Table 4.11.
Basketball is the most commonly reported sport activity of urban and rural boys,
followed by football (soccer). Basketball is also the most commonly reported sport
activity of rural girls, whereas basketball and volleyball are reported about equally
among urban girls. Smaller percentages of children of boys and rural girls report
participation in volleyball. No rural children report participation in baseball
compared to small percentages of urban boys and girls.

Games of chase are reported more often by girls (urban 58%, rural 47%) than
boys (urban 35%, rural 10%). Urban and rural girls also report more involvement in
games of hide and seek, 30% and 32%, respectively, compared to urban and rural
boys, 9%. and 7%, respectively.

Bicycling is reported by small numbers of children. Small numbers of urban
boys and girls report skating (7) and karate (4), whereas one rural boy and one rural

girl report dancing.

86

Light/sedentary activities indicate a sex difference. More girls report playing
with dolls and more boys report playing with cars and marbles. More boys also report
playing videogames, 12% urban and 5% rural, in contrast to only one urban girl.

Television Viewing. Children were asked to indicate how much time they spent
viewing television. Results are summarized in Table 4.12. Overall, about 11% of
children in the 4‘“, 5‘“ and 6‘“ grades report either not having a television and/or no
television viewing. Urban-rural contrasts in viewing television less than one hour and
between 1 and 2 hours are small. About 47% of boys and 37% of girls report less than
one hour, and about 21% of boys and 26% of girls report watching television 1 to 2
hours. Relatively more urban boys (28%) report watching television for more than 2
hours per day than rural boys (13%); in contrast, similar percentages of urban (27%)
and rural (23%) girls report viewing television for more than 2 hours per day.

lutensity of Activities. An attempt was made to estimate the intensity of the
activity reported before and after school by the 4‘“, 5‘“ and 6‘“ grade children.
Activities were classiﬁed as follows:

Very light - includes activities involved in making the bed, doing dishes and
running errands close to home (and requiring a short period of time),

Light — includes housecleaning (sweeping, mopping), shucking corn, removing
grains from cobs, assisting with family business, cooking,

Moderate -— includes feeding, cleaning and herding animals; milking cows/
goats; washing clothes; grinding corn; making, delivering and/or selling tortillas;
gathering chapulines,

Moderate-to-vigorous — clearing farm ground, carrying water, cutting and
gathering wood, cutting and carrying feed for animals.

Results are summarized in Table 4.13. Rural children, boys more so than girls,
report daily participation in household-related activities classiﬁed as moderate and

moderate-to-vigorous in intensity compared to urban children. Urban boys, on the

87

other hand, report more household-related activities that are very light or light in
intensity. Urban and rural girls do not differ markedly in reported frequencies of
daily participation in household-activities classiﬁed a very light and light.

Activities During School Break. The daily school schedule includes a 30
minute break for lunch. Activities during the break reported by 4‘“, 5‘“ and 6‘“
children are summarized in Table 4.14. During this time, many boys are involved in
physical activities. About equal percentages of rural and urban boys report
involvement in games of running and chasing (35% rural, 31% urban), and in sport
(56% rural, 48% urban). Basketball ball is the preferred sport of rural boys and
soccer in urban boys. On the other hand, relatively more urban (20%) than rural
(9%) boys report sedentary activities during the break — sitting, eating, chatting.

About equal percentages of rural and urban girls report involvement in games of
running and chasing during the break (48% rural, 49% urban), but relatively more rural
(3 8%) than urban (6%) report involvement in sport during the break. Basketball is the
preferred sport of rural girls, whereas small but equal numbers of urban girls report
participation in basketball and football (soccer). More urban (42%) than rural (14%)
report sedentary activities during the break. The sex difference in sedentary activities

during the school break is more marked in urban than in rural children.

Dietary Information of 4‘“, 5‘“ and 6‘“ Grade Children

Children in the 4‘“, 5‘“ and 6‘“ grades were asked to list the foods that they
consumed at each meal in the past 24 hours. Complete records were provided by 67
rural children and 97 urban children. Overall, urban children reported a greater number
of individual food items at the three meals than to rural children, 66 compared to 47,
respectively. The total number of foods and the ten foods reported most often by the
children at breakfast (desayuno), lunch (M) and dinner (o_e_r_iu) are listed in Tables

4.15, 4.16 and 4.17, respectively. Urban children reported more diversity in diet,

88

speciﬁcally at breakfast and dinner. The total number of foods reported at lunch was
similar in rural and urban children. Animal protein represented in meats and meat
derivatives were, in general, rather limited in the diets of rural children.

Rural and urban children reported 25 and 34 different food items at breakfast,
respectively. However, the frequencies of food items reported at breakfast were 165
among the 67 rural children and 129 among the 97 urban children, which suggests
2.5 items per child among rural children and 1.3 items per child among urban
children. Bread, chocolate, milk and coffee were the most commonly reported
breakfast foods among both rural and urban children. The ﬁve most commonly
reported breakfast foods also included cereal and milk shakes in urban children, and
tortillas in rural children.

The number of food items reported at lunch was reasonably similar in rural (38)
and urban (44) children. The frequencies of food items reported at lunch were 152
among the 67 rural children and 149 among the 97 urban children, which translates to
2.3 items per child among rural children and 1.5 items per child among rural
children. There was, however, a major rural-urban contrast. The three most
frequently reported items among rural children were soft drinks, orange juice and a
fruit drink (agua frutas), which were reported by 30%, 22% and 18% of the children,
respectively. The next three most commonly reported food items among rural
children were bread, tortillas and sauces (_sa_lsu), each of which was reported by 16%
of the children. Lunches of urban children were more substantive: chicken, beans,
rice, chicken broth, and eggs, which were reported by 10% to 14% of the children.
Other food items among the ten most often reported by urban children were p_a_s_t2_r
(noodle) soup, meat broth, and meat. Only 8% of urban children reported soft drinks
among the ten most common items at lunch.

Almost twice as many food items were reported for dinner among urban children

(43 items) compared to rural children (23 items). In contrast to breakfast and lunch,

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soft drinks and fruit drinks were not among the ten most often reported food items
among rural children. The frequency of food items was 76 among the 67 rural
children, which suggests that only one item was consumed per child (1.1) at the
evening meal. Five of the ten most frequently reported items were animal derivatives,
i.e., animal protein sources. Except for eggs and chicken, reported by 6% and 5% of
the children, respectively, dinner items reported by urban children were largely starch-
based. The frequency of food items for dinner reported by the 97 urban children was
131, which suggests that 1.4 items were consumed per child at the evening meal.
Overall, the diets reported by 4‘“, 5‘“ and 6‘“ grade children in the rural and
urban communities are rather limited, speciﬁcally in animal protein. Somewhat
surprisingly, t_or_ti_l_l_ss and beans, often reported as staples of the Mexican diet, are
relatively lacking among the food items reported by the urban children. Among rural
children, 20%, 25% and 25% reported consuming to_rtulus and beans at breakfast,

lunch and dinner, respectively.

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Chapter 5

Discussion

The present study considered the growth status and physical ﬁtness of primary
school children, 6-13 years of age, living under contrasting conditions in two
communities, one urban and one rural, in the Valley of Oaxaca, southern Mexico. The
sample can be viewed as generally representative of the public primary school
population in rural areas and in expanding pm of Oaxaca, not of the more afﬂuent
segment of the population whose children tend to attend private schools. The sample
was divided into two age categories, 6-9 and 10-13 years. The analysis was set in the
context of four questions and hypotheses dealing with growth status, physical ﬁtness,
the prevalence of stunting and wasting, and the prevalence of overweight and obesity.

Activities and foods consumed by 4‘“, 5‘“ and 6‘“ grade children were also described.

Growth Status

It was hypothesized that urban school children would have better grth status as
assessed with height, weight and other anthropometric indicators than rural school
children. The hypothesis was partially supported. Absolute body size (height and
weight), trunk (sitting height) and estimated leg length, skeletal breadths on the trunk
(biacromial and bicristal breadths) are signiﬁcantly greater in urban than in rural school
children. Urban-rural contrasts in skeletal breadths on the extremities (biepicondylar
and bicondylar breadths), limb circumferences, estimated limb muscle circumferences,
and subcutaneous fatness do not consistently differ by age group and sex.

The data for weight, height, sitting height and estimated leg length in urban and
rural children of Oaxaca are generally consistent with data for school children in several

European countries (Bielicki, 1986), Africa (Spurgeon et al., 1984; Cameron et al., 1992),

91

and China (Lin et al., 1992a) in showing more favorable growth status in urban compared
to rural children. Most studies, however, are limited to height and weight. Similar
contrasts have been reported in several studies of Mexican children dating to the 19603.
The studies in Mexico have generally compared the grth status of a rural or urban
sample relative to reference values for children in Mexico City or the United States.
Results consistently indicate smaller body size in rural school children and in children
from other urban centers in Mexio (Vega-Franco and Robles-De la Vega, 1962; Perez-
Ortiz and Mora, 1967; Pryor and Thelander, 1972; Arechiga and Serrano, 1981; Lopez-
Alonso, 1995). The data for Mexico also indicate marked differences in growth status of
urban children when they are classiﬁed by socioeconomic status (Perez Hidalgo et al.,
1965; Villanueva, 1979). More recent data from the 19903 indicate that primary school
children from urban centers of Sonora and Veracruz (Peﬁa Reyes et al., 2002) compare
favorably in height to the commonly used reference data (Ramos Galvan, 1975) for
Mexican children. However, the more recent samples are heavier and have a higher body
mass index (BMI), which have implications for overweight and obesity.

Urban-rural contrasts in growth status reﬂect to a large extent the inequitable
distribution of and access to resources within a country. These include economic,
educational, nutritional and health-related resources. Resources are often concentrated
in urban centers and are limited in the extent to which they ﬁlter into expanding areas
of cities in Latin America and into the rural areas. The data for Latin America are also
inﬂuenced by recent migrations to urban centers, which have lead to the expansion of

urban developments (colonias in Mexico), many of which are slums with poor housing,

 

marginal access to resources and limited employment opportunities.

Migrants do not ordinarily differ in physical characteristics from sedentes in
their respective communities (Bogin, 1988), and this is also true of the growth status
of eventual migrants and sedentes in Oaxaca (Malina et al., 1982). However, it is

well documented that the growth status of offspring born to migrants to urban centers

92

improve in their growth status compared to children in the home communities (Boas,
1912, 1922; Goldstein, 1943).

A question of interest in the present study is the growth status of children born in
San Juan Chapultepec or the city of Oaxaca, and those born in other communities in the
state of Oaxaca or in other states of Mexico. Information on the place of birth of all except
four children in the sample of school children from San Juan Chapultepec was available:
75% of the children were born in San Juan or the city of Oaxaca, 18% were born in other
areas of the state of Oaxaca, and 6% were born in other states of Mexico (including one
child who was born in the United States). The heights, weights and BMIs of children born
in San Juan or the city of Oaxaca, in other communities in the state of Oaxaca, and in other
states of Mexico do not differ signiﬁcantly (Table 5.1). Information was not available on
the age of the child at the time of migration for children whose families moved into the
£01m. However, about 75% of the families of the school children for whom information
was available (236 of 3 17) lived in the chouLa for 10 years of less.

Corresponding information for children in Santo Tomas Mazaltepec indicated that
87% of the children were born in the community while 4% were born in other areas in
the state of Oaxaca and 7% were born in other states of Mexico. Information on place
of birth was not available for 8 children. Boys born in the rural community and those
who were born elsewhere did not differ in height, weight and the BMI. Girls born in
other areas of Oaxaca (n=9) or other states of Mexico (n=15) were signiﬁcantly heavier
and had a larger BMI than girls born in the community, but the three groups did not
differ signiﬁcantly in height (Table 5.2).

Results of the present comparison for height and weight are consistent with a
similar comparison of about 30 years ago between primary school children resident in
two comm of Oaxaca, one of which was San Juan, and two rural Zapotec-speaking
communities, one of which was Santo Tomas (Malina et al., 1981). The earlier

comparison also indicated no urban-rural difference in the thickness of the triceps

93

skinfold for girls, but indicated a smaller estimated midarm muscle circumference in
rural boys and girls. In the present study, the triceps skinfold did not differ between
urban and rural girls and between urban and rural boys 6-9 years; however, urban boys
10-13 years had a thicker triceps skinfold (Table 4.3). Estimated arm muscle was
signiﬁcantly greater in urban boys 10-13 years and in urban girls 6-9 years, and did not
differ between urban and rural boys 6-9 years and girls 10-13 years (Table 4.2).
However, the age-adjusted means tended to be larger in urban children in the four age
groups. The earlier study did not analyze the data by corresponding age groups.

Although urban children tend to be taller and heavier than rural children, both
samples from Oaxaca are, on average, consistently shorter and lighter compared to
United Stated reference data. On average, the heights of urban boys and girls fall at or
above the 10‘“ percentiles but approach the 25‘“ percentiles at several ages, whereas the
heights of rural boys and girls ﬂuctuate between the 5‘“ and 10‘“ percentiles (Figures 4.1
and 4.2). Mean weights of urban children of both sexes tend to be above the 25‘“
percentiles of the reference values. In contrast, mean weights of rural boys and girls
are at or below the 25‘“ percentiles (Figures 4.3 and 4.4).

The growth status of the current sample of Oaxaca children fares better relative to
United States reference values than Oaxaca children surveyed between 1968 and 1972.
A combined sample of rural and urban children, 6 to 13 years of age, in 1968-1972 had
heights that were, on average, consistently below the 5‘“ percentiles of United States
reference data and weights that approximated, on average, the 5‘“ percentiles of United
States reference data (Malina, 1983). This comparison needs to be tempered with
caution. Different reference values were used in the present (Centers for Disease
Control and Prevention, 2000) and earlier (Hamill et al., 1977) comparative studies.
Heights of national samples of American children in surveys carried out from the 19603
through 1994 have not changed signiﬁcantly, although there have been major increases

in body weight in the most recent national survey, 1988-1994. The increase in weight

94

was of major public health concern and the body weights from the most recent survey
were not used in the construction of the new growth charts (Kuczmarski et al., 2000).
Allowing for these caveats in the United States reference data, the growth status of
urban and rural school children in Oaxaca in 2000 has improved compared to that of

urban and rural school children in 1968-1972.

Overweight, Obesity and Wasting

The urban girls 6-9 years and boys 10-13 years had a signiﬁcantly larger body
mass index (BMI) than rural children in the respective age groups, but the BMI did not
differ between urban and rural girls 10-13 years and boys 6-9 years (Table 4.1). The
trends in the BMI are generally consistent with the estimated prevalence of overweight
and obesity in the urban and rural children (Tables 4.8 and 4.9). Across the age range
6-13 years, urban children show a higher prevalence in overweight than rural children,
11.0% and 5.1%, respectively, in boys (x2=4.49, p<0.05), and 14.5% and 7.6%,
respectively, in girls (x2=4.43, p<0.05). In contrast, obesity is relatively rare in this
sample of urban and rural children, 1.1% and 4.0%, respectively, in boys (x2=3.33,
NS), and 1.1% and 2.4%, respectively, in girls (x2=1.10, NS).

The estimated prevalence of overweight and obesity in the present study was
based on the internationally recommended criteria of Cole et a1. (2000). These criteria
were applied to several other samples of Mexican children to provide a comparative
perspective: primary school children in urban centers of Sonora and Veracruz (Pena
Reyes et al., 2002) and Mexico City (Siegel, 1999), and rural Tarahumara school in
Chihuahua children in northern Mexico (Peﬁa Reyes et al., in preparation). The
estimated prevalences of overweight and obesity are summarized in Table 5.3. Rural
Mexican primary school children from indigenous communities in Oaxaca and
Chihuahua have a low prevalence of overweight, about 4% in boys and 8% in girls.

Obesity in rural school children is relatively uncommon, about 1%. Urban boys in

95

Oaxaca have a lower prevalence of overweight (11%) and obesity (4%) compared to
urban boys in other centers of Mexico (19-23% and 9-14%, respectively). The contrast
among girls from different urban areas is less for overweight, 14% in girls from Oaxaca
compared to 17-23% in girls from larger urban centers. On the other hand, obesity is
relatively uncommon in urban Oaxaca girls (2%) compared to girls in other urban
centers (6-9%). Corresponding data for other samples utilizing the internationally
recommended criteria (Cole et al., 2000) are not presently available.

Estimates of overweight and obesity in a population are based on the BMI, and
both conditions indicate excess weight-for-height. Overweight and obesity are
sometimes referred to as forms of overnutrition, but chronically excessive energy
intake is only one part of the equation. Chronic physical inactivity is another important
factor in the etiology of overweight and obesity. The opposite extreme of overweight/
obesity is wasting, a form of chronic undemutrition that indicates low weight-for-
height (World Health Organization, 1995). In the present study, wasting was deﬁned as
a BMI below the 5‘“ percentiles of age- and sex-speciﬁc reference data for the United
States (Centers for Disease Control and Prevention, 2000). The same criteria were
applied to the data for the children from other areas of Mexico used in the comparisons
of overweight and obesity (see above). Results are summarized in Table 5.4. Overall,
wasting is relatively uncommon among rural and urban Mexican primary school
children 6-13 years of age. Estimated prevalences are lowest in rural (2%) and urban
(15) children in Oaxaca and rural Tarahumara children in Chihuahua (<1% boys, 2%
girls). Estimates are 2% (boys) and 3% (girls) in Sonora, 3% (boys and girls) in
Veracruz, and 6% (boys) and 4% (girls) in Mexico City. The somewhat higher
estimates of wasting for primary school children in Mexico City are perhaps somewhat
surprising. They may reﬂect more extreme conditions of poverty, or perhaps later
onset of the adolescent grth spurt during which weight-for-height relationships

change appreciably (Malina and Bouchard, 1991).

96

Stunting

In contrast to wasting, which indicates low weight-for—height, stunting refers to
short stature or deﬁcient linear growth. Growth in height is a record of a child’s
nutritional history, and a high prevalence of growth stunting, deﬁned as a z-score
below —2.0 relative to age- and sex-speciﬁc reference values, generally accepted as
evidence of chronic undemutrition in a community (World Health Organization,
1995). Most stunting occurs during the preschool years when the rate of growth in
height is especially rapid (Malina and Bouchard, 1991). Estimated rates of growth in
height over a one year interval (1978-1979) suggest that the height of school children
6-13 years in Santo Tomas is more indicative of insults experienced during the
preschool years than during the school ages (Buschang and Malina, 1983).

In the present study (Table 4.6), the prevalence of stunting is almost twice as great
in rural (about 29%) than in urban boys and girls (about 15%). Corresponding data for
other samples 6—13 years of age in Mexico are not available. Estimates of stunting
(height more than two standard deviations below that expected for age) for ﬁrst grade
children at school entry in 1994 vary among states in Mexico (Secretaria de Salud, 1998).
Estimates are highest in Chiapas (44.1%), Oaxaca (43.4%) and Yucatan (36.6%), all
states with a high percentage of rural indigenous populations. Estimates for rural
children 6-9 years of age in the present study are 27.4% in boys and 29.2% in girls, which
are lower that the statewide estimate for rural children at entry to school (43.4%).

The prevalence of stunting was estimated for the sample of rural Tarahumara
school children in Chihuahua using the same reference values (Centers for Disease
Control and Prevention, 2000) as in the present study. The comparative data are
summarized in Table 5.5. Among children 6-9 years, estimates of stunting are slightly
lower in rural Zapotec in Oaxaca compared to rural Tarahumara in Chihuahua. Among
older children 10-13 years, estimates of stunting a reasonably comparable in rural

Oaxaca and Chihuahua. In contrast, estimates of stunting among urban children in

97

Oaxaca are about one-half of the estimates among rural children in Oaxaca and

Chihuahua.

Physical Fitness, Physical Activity and Diet

It was hypothesized that urban school children would perform better on tests of
physical ﬁtness than rural school children. The hypothesis was partially supported.
Urban children, on average, tended to perform better in the sit and reach, sit-ups,
standing long jump and dash (10-13 years only), but results were not consistently
signiﬁcant. Rural children 6-9 years performed better in the dash. There were no
urban-rural differences in grip strength, although strength per unit body mass was
greater in rural children. Rural children in grades 1-3 and rural boys in grades 4-6
performed better in the distance run. On the other hand, urban girls in grades 4-6
performed signiﬁcantly better in the distance run.

The urban-rural contrasts in physical ﬁtness may reﬂect, in part, physical
education in the respective schools and the pattern of daily activities. The rural
school has one physical education period per week (30-45 minutes). The class is
conducted by the classroom teacher. The ﬁrst part of the period is spent marching
around the patio of the central plaza of the community, followed by free play. Most
children participate in sport, speciﬁcally basketball. There is little, if any, instruction
and practice of speciﬁc motor skills. The urban school, in contrast, has a physical
education teacher who offers formal classes (30-45 minutes) once per week. Time is
usually devoted to the practice of speciﬁc motor skills and routines, which vary from
grade to grade and throughout the school year.

Several of the ﬁtness tests (e.g., standing long jump, sit-ups) appeared more familiar
to the urban than to the rural children. This may contribute to some of the contrasts
between the urban and rural samples, i.e., familiarity with the tests. Indeed, some of the

younger rural children had difficulty with the protocol for the standing long jump.

98

In contrast to physical education, the rural children, especially boys, spend a
good deal of time in household chores related to the care of animals (Table 4.10).
These chores require muscular strength and moderate endurance in walking back and
forth to the ﬁelds for animal feed (and carrying the feed back to the household) and for
animal grazing. Gathering and carrying wood and carrying water are other household
chores of many boys. This may contribute to the generally better distance run
(endurance) performances and the better grip strength per unit body size in rural boys.

The chores of rural girls are largely involved with food preparation (Table 4.10).
These activities include shucking corn, walking back and forth to the corn grinding mill
(and carrying the maize), and occasionally assisting with the sale of tortillas, which
involves considerable walking. The activities of girls also include some chores related
to animal care (same as boys), carrying water, and gathering chapulines. All these
activities require regular walking and carrying. Hence, this may contribute to the better
grip strength per unit body size in rural compared to urban girls. Although rural girls
are seemingly more active in walking and carrying tasks, this does not necessarily
translate into better endurance (distance run performance). It may reﬂect the
observation that many of the activities of rural girls take place relatively close to home
and with age, older rural girls are generally more homebound than older urban girls.
Rural girls 6-9 years perform better in the distance run than urban girls, but urban girls
10-13 years perform slightly better in the distance run than rural girls.

The strength and motor ﬁtness of children in Santo Tomas were also studied in 1978.
Performances in the dash, standing long jump, ball throw for distance, and grip strength
were consistently poorer than those of American children. When performances were
adjusted for body size differences between the samples, the performances of the rural
Zapotec children were generally commensurate to their smaller body size, especially 6
through 9 years of age, although the rural children tended to throw better than expected for

their small body size (Malina and Buschang, 1985). Comparison of the mean

99

performances of children in Santo Tomas in 2000 with those of the sample in 1978
indicates several trends. The recent sample of boys and girls is stronger in grip strength,
probably reﬂecting their larger body size. Differences between the 2000 and 1978 samples
in the 35 yard dash (32.3 m) are small and inconsistent across the age range. In contrast,
the standing long jump performance of the 2000 sample is, on average, consistently poorer
than the performances of the 1978 sample in both sexes (Malina, 2002).

Urban-rural comparisons of physical ﬁtness are rather limited, but suggest
variable results depending on ﬁtness tests being used. The physical ﬁtness of Japanese
children and adolescents varies by item and among prefectures. In Kyoto, for example,
rural elementary school children (about 7-12 years) performed better in muscular
strength (grip, back), motor ability (50 m dash, standing long jump, ball throw for
distance), and muscular endurance (chinning), but urban children performed better in
agility (continuous hopping). On the other hand,‘urban boys 9-18 years in the Gifu
prefecture performed better than their rural peers in muscular strength (back) and motOr
ﬁtness (50 m dash, standing long jump), but urban and rural boys did not differ in grip
strength. Urban girls had better motor ﬁtness than their rural peers, but there were no
urban-rura1 differences in muscular strength (grip, back). Both rural boys and girls had
better maximal aerobic power than their urban peers (Tamura, 1975).

Observations on rural and urban children in Oaxaca are reasonably similar to those
for Japanese children. The rural children tended to perform better in the endurance task
(8 and 12 minute run), with the exception of girls 10-13 years, whereas there were no
differences in muscular strength. The urban children also performed better in the
standing long jump, but urban-rural differences were not consistent for the dash.

Data from Poland in the 19603 indicated better performances in the vertical jump
and agility by urban boys 7-13 years of age, but no consistent differences in the
performances of urban and rural boys in a dash, medicine ball throw and grip strength

(Miemik, 1965). On the other hand, 10 year old urban Polish boys and girls performed

100

better than their rural peers in a 30 m dash, a 1 kg medicine ball throw, the vertical jump,
squat thrusts (muscular endurance), and an agility run (Pilicz and Sadowska, 1973).

Urban-rural comparisons of physical ﬁtness in some areas of the world must be
tempered by contrasts in socioeconomic and nutritional status. Rural, low
socioeconomic status children in South Africa, for example, have poorer grip strength
than urban, high socioeconomic status children, but rural-urban contrasts in
neuromuscular reaction time and pulse recovery after exercise (cardiovascular
endurance) are inconsistent (Henneberg and Louw, 1998).

A question of interest is the physical ﬁtness status of the Oaxaca children compared
to healthy, well nourished children. Reference values for several indicators of physical
ﬁtness permit several comparisons. The F itrressgram (Cooper Institute for Aerobic
Research, 1994) provides “healthy ﬁtness zones” for several components of health-
related physical ﬁtness, including the BMI and percentage fat (predicted from skinfolds).
Mean BMIs of rural and urban children in Oaxaca fall well within the “healthy” zone.
The percentage body fat of Oaxaca children was predicted from the sum of the triceps
and medial calf skinfolds following the protocol of the Fitnessgram (Lohman, 1994).
Mean estimated percentage fat of the rural and urban children fall towards the low end of
the “healthy ﬁtness zone” in both sexes. The recommended low ends of the “healthy
ﬁtness zone” are 10% fat in boys and 17% fat in girls. Mean estimates for rural and
urban boys 6-9 years are 12.3% and 12.7%, respectively, and for rural and urban boys 10-
13 years are 12.6% and 14.9%, respectively. Estimated means for rural and urban girls 6-
9 years are identical, 15.8%, and are below the low end of the “healthy ﬁtness zone,”
while those for rural and urban girls 10-13 years are 17.7% and 17.0%, respectively.

The sit-and-reach is scored on a pass-fail basis in the Fitnessgram. Mean values
for the sit-and-reach performance of the rural and urban Oaxaca children exceed the
passing levels (20 cm in boys, 23 cm in girls). The mean sit-and-reach performances of

Oaxaca children approximate the medians for the reference sample of the American

101

Alliance for Health, Physical Education, Recreation and Dance (1980). The

F itnessgram includes modiﬁed sit-ups (curl-ups), but it is not a timed test. Rather,
children are instructed to perform the curl-ups at a slow and controlled pace of about
20 per minute. Hence, the data are not comparable to values in the present study.

Reference data for the distance run and/or walked in 8 and 12 minutes are not
available. The American Alliance for Health, Physical Education, Recreation and
Dance (1980) provide reference values for the distance run (yards) in 9 minutes.
Expressing the medians and means as yards per minute and meters per minute,
respectively, provides an indirect comparison. Allowing for the differences in
measurement units, the distance run performance of rural and urban Oaxaca children,
estimated as meters per minute, is quite similar to the reference. The aerobic
performance of the Oaxaca children is perhaps more impressive in the context of their
smaller body size, speciﬁcally leg length, which is related to stride length. This would
suggest better aerobic ﬁtness in the Oaxaca children.

The three remaining items in the physical ﬁtness battery used in the present study
include static strength (grip strength), explosive strength (standing long jump) and
running speed (35-yard dash). The three items are highly correlated with body size
(Malina, 1975, 1994a). Hence, given the smaller body size of the Oaxaca children, one
would expect lower performances in these three tasks. Reference values for healthy,
well-nourished children are not available with the exception of the standing long jump.
Tests of running speed use different distances. Comparisons of grip strength are
limited by variation in the type of dynamometer. Estimates of strength based on
different dynamometers are not directly comparable.

Data for a mixed-longitudinal sample of Philadelphia children 6-13 years of age
tested in the mid-19603 include the standing long jump, the 35-yard dash and grip
strength (Malina, unpublished). The jumping and running protocols are the same as

used in the present study. Grip strength was measured with a Narragansett

102

dynamometer in the Philadelphia study, whereas an adjustable Stoelting dynamometer
was used in the present study. Mean performances of rural and urban Oaxaca children
on the standing long jump and 35—yard dash are consistently lower than corresponding
age- and sex-speciﬁc values for the mixed-longitudinal sample of Philadelphia
children. Allowing for differences in type of dynamometer, the grip strength of Oaxaca

children is also consistently lower than that of Philadelphia children.

Urban and Rural School Children in Oaxaca — An Overview

The growth status of children is often viewed as a mirror of conditions in society and as
speciﬁcally reﬂecting the overall health and nutritional status of a community. The growth
status of the urban and rural school children can be viewed as reﬂecting conditions in the state
of Oaxaca and speciﬁcally in the Valley of Oaxaca, which are inﬂuenced by economic
development in the area and by an increasing proportion of small land owners who are
abandoning rural communities in search of jobs closer to or in the more attractive urban areas
(Ruiz-Cervantes, 1988). The larger heights and weights of the urban sample probably reﬂect
improved health and nutritional conditions in the city of Oaxaca compared to rural areas.
Improved conditions are reﬂected in indicators as sewage disposal and potable water, better
housing, access to outpatient clinics, better schools, and availability of a regular food supply.

Although it is difﬁcult to specify direct contributions of these factors to the grth
status given the complexity of the cellular processes that underlie growth, this
interpretation is consistent with an index of nutritional deﬁcits (indicadores do
desnutricion) developed by the National Institute of Nutrition (Roldan et al., 2000). The
variables used to derive the index include primarily health and social indicators so that
the index might be more appropriately labeled social undemutrition (desnutricion social):
height deﬁcit at school entrance, infant mortality, school age mortality, percentage of
deaths related to respiratory disease, percentage of deaths related to diarrhea, percentage

of indigenous population, and the index of marginalization (indice de marginacion,

103

described earlier, Chapter 2). The index of marginalization was based on education,
housing, population distribution and income (Consejo Nacional de Poblacion, 1998).
Based on these indicators, nutritional grades were classiﬁed as follows:

Indices $15 - low deﬁcits

Indices 15.1 to 20.0 -— moderate deﬁcits

Indices 20.1 to 30.0 — important deﬁcits

Indices 230.1 — severe deﬁcits.

The nutritional index for the state of Oaxaca was 35.78; the corresponding
indices for the city of Oaxaca and rural communities in the state were 11.53 and
41.81, respectively. Indices for the rural areas fell in the severe range. By way of
comparison and as examples, the nutritional index was 7.18 for Baja California
Norte, 7.28 for the Federal District, 7.90 for Sonora, 17.19 for Durango, and 30.33
for the Yucatan (Roldan et al., 2000).

If the index of marginalization is treated separately, the index for the state of
Oaxaca places the state in a very high of level marginalization. Corresponding
classiﬁcations for other states are very low marginalization for the Federal District
and Baja California Norte, low marginalization for Sonora, medium marginalization
for Durango, and high marginalization for Yucatan.

The indices of nutritional deﬁcit and marginalization highlight the relatively
poor conditions of life in small, rural communities in the state of Oaxaca in contrast
to the better conditions characteristic of urban centers. It is such marginal conditions
that contribute to the urban-rural contrast in growth status observed in the present
study and to the greater prevalence of stunting in rural children. However, the urban
sample from Oaxaca is consistently shorter than primary school children from other
urban centers in Mexico (Peﬁa Reyes et al., 2002).

Although the growth status (size attained) of urban children is better than that of

rural children, both samples are shorter compared to reference values recommended by

104

the World Health Organization. The World Health Organization (1995) recommended
the use of reference data for United States children. The reference values, or “growth
charts,” for United States children have been recently revised (Centers for Disease
Control and Prevention, 2000). Compared to the new reference values, urban children
in Oaxaca tend to approximate the 10‘“ percentiles but approach the 25‘“ percentiles at
several ages, whereas the heights of rural boys and girls ﬂuctuate between the 5‘“ and
10‘“ percentiles. In contrast to the present sample, rural and urban primary school
children surveyed in Oaxaca in 1968-1972 have mean heights that approximated or
were below the 5‘“ percentiles of United States reference data.

Thus, the growth status of urban and rural Oaxaca children has improved over
the past 30 years or so (Malina, 2002). Urban boys 6-13 years of age in 2000 are
about 5.1 cm taller and 4.9 kg heavier than urban boys in 1972. Similarly, rural boys
6-13 years of age in 2000 are about 6.6 cm taller and 4.3 kg heavier than rura1 boys
in 1968. The magnitude of the urban-rural differences in height, weight and the BMI
in 2000 are smaller than the corresponding differences in 1968/1972 among boys 6-9
years, but the opposite is true among boys 10-13 years, i.e., the magnitude of the
urban-rural difference in height, weight and the BMI in 2000 is greater than in 1968/
1972. The difference in older boys is especially marked in body weight. The urban-
rural difference among 10-13 year old boys in 1968/1972 was 2.3 kg, while the
corresponding difference in 2000 is 5.7 kg. This is reﬂected in the signiﬁcantly
greater prevalence of overweight/obesity in the current sample 10-13 year old urban
boys compared to rural boys of the same age (Table 4.8). The corresponding
estimates among younger boys 6-9 years did not differ between urban and rural boys.

Generally similar trends are apparent among the urban and rural girls over the
past 30 years. Urban girls 6-13 years of age in 2000 are about 7.0 cm taller and 5.4
kg heavier than urban girls in 1972. Similarly, rural girls 6-13 years of age in 2000

are about 5.7 cm taller and 3.8 kg heavier than rural boys in 1968. In contrast to

105

boys, the magnitude of the urban-rural differences in 2000 are greater for weight and
the BMI compared to the corresponding differences in 1968/1972 among girls 6-9
years; the magnitude of the urban-rural difference for height was about the same in
1968/1972 and 2000. Among girls 10-13 years, the magnitude of the urban-rural
difference in height, weight and the BMI in 2000 is greater than in 1968/1972, which
is similar to the trend in boys 10-13 years. In contrast to boys, the prevalence of
overweight/obesity among the current sample of urban girls is greater in both
younger (6-9) and older (10-13) year old girls (Table 4.9).

The improved growth status of primary school children in Oaxaca probably reﬂects
better health and nutritional conditions compared to those of 20-30 years ago. Although
growth status has improved, a signiﬁcant percentage of urban and especially rural
primary school children are stunted in growth (Table 4.6). The estimated prevalence of
stunting is about twice as great in the rural children (about 30%) compared to the urban
children (about 15%). Growth stunting is generally viewed as reﬂecting nutritional
insults during infancy and early childhood. Hence, signiﬁcant numbers of urban and
rural children have probably been reared under poor conditions. The growth and ﬁtness
characteristics of stunted and non-stunted children are currently under study.

While mean heights of primary school children have increased, on average,
over time, mean weights have increased proportionally more, particularly in the
urban population. This is reﬂected in a signiﬁcantly greater prevalence of overweight
in the urban than the rural samples. Nevertheless, the prevalence of overweight and
obesity among urban primary school children in Oaxaca is less than corresponding
estimates in school children from other, larger urban centers in Mexico (Table 5.3).

Taken together, the data for primary school children in Oaxaca present a picture
labeled as the epidemiological paradox — an increasing prevalence of overweight/obesity
in the face of persistent chronic undemutrition. This is a characteristic of countries, or

areas within a country, that are experiencing an economic and nutrition transition (Popkin

106

et al., 1996). Rapid urbanization is a characteristic of the transition, and the urban
population of the state of Oaxaca has increased from 32% in 1980 to 43% in 2000 (Table
2.1). Migration to cities has inﬂuenced the demographic make-up of rural communities,
often contributing to economic disparities between the areas. For example, about 29% of
the urban population of Oaxaca has an income corresponding to 1 or 2 minimum wages
compared to only 16% of the rural population. And, about 34% of the urban population
has an income corresponding to 2 to 5 times the minimum wage in contrast to 15% of the
rural population. On the other hand, about 49% of the rural population received no
income compared to only 6% of the urban population (INEGI, 2000, see Table 3.2).
Although these ﬁgures are estimates, they affect the purchasing power of families which
inﬂuence living conditions, including habits related to diet and physical activity, and in
turn the health and nutritional status of children.

Although the observations on the physical activities of 4‘“, 5‘“ and 6‘“ grade children
in the urban and rural communities are limited, they suggest less regular physical activity
among the urban children, which may be a contributory factor to the increasing
prevalence of overweight and in some cases obesity. In contrast, the rural children are
more regularly involved in activities of moderate intensity, and in some instance activities
of moderate-to-vigorous intensity. These activities are related largely to household
chores and subsistence needs, e. g., gathering wood, carrying water, caring for animals,
and so on. Regular involvement in such activities involving walking and carrying loads,
may contribute to the observed rural-urban difference in cardiovascular endurance
(distance run) and muscular strength per unit body mass. Although methods of
classifying youth as active and less active vary among studies, there is a reasonably
consistent observation that more active youth are generally more ﬁt in measures of
cardiorespiratory endurance. On the other hand, results for other components of health-
related physical ﬁtness are somewhat inconsistent among studies, suggesting that habitual

physical activity is only one of several factors that inﬂuences ﬁtness (Malina, 1994b).

107

Although limited to reports of 4‘“ through 6‘“ grade children, urban children
indicate a more varied diet as reﬂected in a greater number of individual food items

reportedly consumed at the three meals, breakfast (desayuno), lunch (comida) and

 

dinner (cena), in the past 24 hours, 66 versus 47 food items, respectively. This

 

suggests that the urban children have access to a greater variety of foods. However,
the dietary items reported by these older primary school children in the rural and
urban communities are rather limited, speciﬁcally in animal protein. Urban children
report more food items of higher quality animal protein (eggs, red meat). Eggs and
red meat are listed on 10% of the entries of urban children compared to 5% of the
entries of rural children. Somewhat surprisingly, t_o_rt_iﬂus and beans, often reported
as staples of the Mexican diet, are lacking among the food items reported by the
urban children and are indicated rather infrequently by the rural children. Only 4%,
15% and 6% of urban children reported consuming milks, and beans at breakfast,
lunch and dinner, respectively. Tortillas have been largely replaced by bread in the
urban diet. In contrast, among rural children, 20%, 25% and 25% reported

consuming tortillas and beans at breakfast, lunch and dinner, respectively.

108

Chapter 6

Summary and Conclusions

The present study considered the growth status and physical ﬁtness of school
children living in two communities, one urban and one rural, in the Valley of Oaxaca,
southern Mexico, in 1999-2000. The two communities, Santo Tomas Mazaltepec and
San Juan Chapultepec, were chosen because they represented the contrasting living
conditions that may inﬂuence growth and physical ﬁtness of school children.

Santo Tomas is a rural community with a high proportion of Zapotec-speaking
population. It is largely a subsistence agricultural community. Community lands are
generally not high quality to produce adequate resources. Hence, manywomen are
economically active, largely through the sale of tortillas.

San Juan is an urban colonia located on the slopes of the hills west of the city of

 

Oaxaca de Juarez. At present, the colonia is part of the city of Oaxaca. The population

 

is basically Spanish-speaking. The majority of the population of the 991mm, works as
employees or in industry, and in the service sector of the city of Oaxaca.

Study subjects were children enrolled in the primary school in each community.
The project was developed within the activities of the general project: “Secular
change in size, strength and motor ﬁtness in the Valley of Oaxaca, Mexico,” with
Robert M. Malina as principal investigator. A total of 367 children, 180 boys and
187 girls, in the 1“ through 6‘“ grades was measured and tested in the rural
community in the Fall 1999 and Spring 2000, and a total of 341 children, 175 boys
and 161 girls, in the 1“ through 6‘“ grades was measured and tested in the urban
community in the Fall 1999 and Spring 2000. Given the small number of children 14
and 15 years of age (6 in the rural community, 2 in the urban community), the

analysis was limited to school children 6 through 13 years of age. The total sample

109

included 700 children 6 to 13 years of age, 361 from the rural community (177
males, 184 females) and 339 from the urban community (173 males, 166 females).

Anthropometric and physical ﬁtness data were collected at the respective
schools during regular school hours in both communities. The anthropometric
battery included measures of body size (height and weight), segment lengths (sitting
height and estimated leg length), skeletal breadths (biacromial, bicristal,
biepicondylar, bicondylar), limb circumferences (arm and calf), and skinfolds
(triceps, subscapular, suprailiac, medial calf). The body mass index (BMI), the
sitting height/stature ratio, estimated arm and calf muscle circumferences, sum of
skinfolds, and the trunk/extremity skinfold ratio were calculated.

Physical ﬁtness items included motor-and-health-related tasks: right and left
grip strength (muscular strength), 35 yard dash (32.3 meters, speed), standing long
jump (explosive power), sit-and-reach (ﬂexibility), timed sit-ups (30 seconds,
abdominal strength and endurance), and a distance run (8 minutes in grades 1-3 and
12 minutes in grades 4-6, cardiovascular endurance).

An activity and dietary questionnaire was administered in children in grades 4,
5 and 6. Self-reported daily activities and food items consumed in the preceding 24
hours were obtained from children in the 4‘“, 5‘“ and 6‘“ grades. Activities were
divided into those classiﬁed as recreational and those related to household chores.
Time spent viewing television and intensity of household-related activities was also
estimated. Variety of food items and foods consumed at breakfast, lunch and dinner
were compared,

Chronological age of each child was based on the date of measurement and birth
dates obtained from school records and corroborated by parents and teachers if
necessary. Descriptive statistics (means, standard deviations and medians where
appropriate) for all variables were initially calculated by age group and sex in each

community. Children were grouped into whole year age categories, i.e., 6.0 to 6.99

110

deﬁned the 6 year age group, and so on, but were divided in two age groups separately
for each sex, 6-9 and 10-13 years, to address the four questions of the study.

Before systematically comparing the growth status and physical ﬁtness of the
urban and rural children, their mean heights, weights, and BMIs were the plotted
relative to the new United States growth charts to establish the current growth status
of the sample. On average, the heights of urban boys and girls fall at or above the
10‘“ percentiles but approach the 25‘“ percentiles of the reference values at several
ages, whereas the heights of rural boys and girls ﬂuctuate between the 5‘“ and 10‘“
percentiles. Mean weights of urban children of both sexes tend to be above the 25‘“
percentiles of the reference values. In contrast, mean weights of rural boys and girls
are at or below the 25‘“ percentiles. The trends for mean heights and weights suggest
elevated weight-for-height in both the urban and rural samples, which is reﬂected in
the BMI. The BMI, on average, falls between the 25‘“ and 75‘“ percentiles of the
reference data at most ages.

Results of rural-urban comparisons of the growth and performance variables are
summarized in the context of the speciﬁc questions and hypotheses.

1. How do current samples of urban and rural school children 6-12 years of age in
southern Mexico compare in growth status? Hypothesis. Urban school children have
better growth status as assessed with height, weight and other anthropometric
indicators than rural school children. The basic statistic was analysis of covariance
(ANCOVA) with age as the covariate. This hypothesis was partially supported.
Absolute body size (height and weight), trunk (sitting height) and estimated leg
length, skeletal breadths on the trunk (biacromial and bicristal breadths) were
signiﬁcantly larger in urban than in rural school children. Urban-rural contrasts in
skeletal breadths on the extremities (biepicondylar and bicondylar breadths), limb
circumferences, estimated limb muscle circumferences, subcutaneous fatness and

relative fat distribution were not consistently signiﬁcant by age group and sex.

111

2. How do current samples of urban and rural school children 6-12 years of age in
southern Mexico compare in physical ﬁtness? Hypothesis. Urban school children
perform better on tests of physical ﬁtness than rural school children. The basic
statistic was analysis of covariance (ANCOVA) with age as the covariate. The
hypothesis was also partially supported. Urban children, on average, tended to
perform better in the sit and reach, sit-ups, standing long jump and dash (10-13 years
only), but results were not consistently signiﬁcant. Rural children 6-9 years
performed better in the dash. There were no urban-rural differences in grip strength,
although strength per unit body mass tended to be greater in rural children. Rural
children in grades 1-3 performed better in the distance run, but results for children in
grades 4-6 were inconsistent. Older rural boys performed better than urban boys,
although the difference was not signiﬁcant, but urban girls in grades 4-6 performed
signiﬁcantly better than rural girls.
3. How do current samples of urban and rural school children in southern Mexico
compare in the estimated prevalence of growth stunting and wasting? Growth
stunting was estimated using the criteria of the World Health Organization (WHO,
1995), in which stunting is deﬁned as low height-for-age relative to internationally
acceptable reference data. A height below two standard deviations of age- and sex-
speciﬁc reference values is classiﬁed as stunted. Heights of individual children were
converted to z-scores using the protocol and reference values of the new United
States Growth charts (Centers for Disease Control and Prevention, 2000). A z-score
below —2.0 was deﬁned as stunting. Wasting is a form of undemutrition that
indicates low weight-for-height (World Health Organization, 1995). Wasting was
deﬁned as a BMI below the 5‘“ percentiles of age- and sex-speciﬁc reference data for
the United States (Centers for Disease Control and Prevention, 2000).

The sex-speciﬁc prevalences (and 95% conﬁdence intervals) for stunting and

wasting were calculated for each age group (6-9, 10-13 years) and the total sample

112

(6-13 years). Sex-speciﬁc comparisons of the prevalences of stunting and wasting in
the two age groups and the total sample of urban and rural children were tested with
the chi-square statistic. Hypothesis. Rural school children have a higher prevalence
of growth stunting and wasting than urban school children. The hypothesis was
partially supported. The prevalence of stunting was about twice as great in the rural
compared to the urban children, but the prevalence of wasting was very low in both
communities and did not differ.

4. How do the current samples of urban and rural school children in southern Mexico
compare in the estimated prevalence of overweight and obesity? Overweight was
deﬁned relative to the internationally recommended criteria (cut-off points) based on
six national samples (Cole et al., 2000). The sex-speciﬁc prevalences (and 95%
conﬁdence intervals) of overweight and obesity were calculated for each age group
(6-9, 10-13 years) and total sample (6-13 years). The sex-speciﬁc comparison of the
prevalences of overweight and obesity in the two age groups and the total sample of
urban and rural children was tested with the chi-square statistic. HypﬂbuLis. Urban
school children have a higher prevalence of overweight and obesity than rural school
children. The hypothesis was partially supported. The prevalence of overweight was
significantly greater in urban than in rural children, speciﬁcally when the data were
considered across the entire age span, 6-13 years. Within ages groups 6-9 and 10-13
years, the prevalence was greater in urban children, but the results were not
consistently signiﬁcant. The prevalence of obesity in urban and rural school children
was low, and was signiﬁcantly greater only in urban boys 10-13 years.

Activities and dietary items reported by rural and urban children in the upper
grades showed several contrasts. Rural boys reported least involvement in house-
related activities (cleaning, making the bed). About two-thirds of urban boys and
urban and rural girls reported house cleaning chores in contrast to about 40% of rural

boys. There were major differences between urban and rural children in food- and

113

animal-related activities. Relatively few urban children (2-6%) reported
involvement in cooking. About two-thirds of rural girls reported activities related to
the making of tortillas compared to 13% of rural boys, and 14% of rural girls
reported cooking compared to no rural boys. On the other hand, more rural boys
reported gathering wood and getting water than rural girls.

Rural children, speciﬁcally boys, reported major daily involvement in animal-
related activities, caring for animals (70%) and getting animal feed from the pasture
(69%). Smaller percentages of girls reported these activities (8-9%). Small
percentages of urban children reported daily care for pets (3-8%). Small percentages
of rural children (2—4%) reported involvement in farming activities, most often
described as clearing ground.

Basketball was the most commonly reported sport activity of urban and rural
boys, followed by football (soccer). Basketball was also the most commonly
reported sport activity of rural girls, whereas basketball and volleyball were reported
about equally among urban girls. Games of chase and seeking (hide and seek) were
reported more often by urban and rural girls than boys.

Light/sedentary activities indicated a sex difference. More girls reported
playing with dolls and more boys reported playing with cars and marbles. Boys also
reported playing videogames; in contrast, only one urban girl reported this activity.

Urban-rural contrasts in viewing television less than one hour and between 1
and 2 hours per day were small. Relatively more urban boys reported watching
television for more than 2 hours per day than rural boys, but similar percentages of
urban and rural reported viewing television for more than 2 hours per day.

An attempt was made to estimate the intensity of activities reported before and
after school by the 4‘“, 5‘“ and 6‘“ grade children. Rural children, boys more so than
girls, reported more frequent daily participation in household-related activities

classiﬁed as moderate and moderate-to-vigorous in intensity compared to urban

114

children. Urban boys, on the other hand, reported more household-related activities
that were very light or light in intensity. Urban and rural girls did not differ
markedly in reported frequencies of daily participation in household-activities
classiﬁed a very light and light in intensity.

Urban children reported more diversity in diet, speciﬁcally at breakfast and
dinner than rural children. The total number of foods reported at lunch were similar
in rural and urban children. Overall, the diets reported by 4‘“, 5‘“ and 6‘“ grade
children in the rural and urban communities were rather limited. Animal protein
represented in meats and meat derivatives were, in general, rather limited in the diets
of rural children. Somewhat surprisingly, tortillas and beans, often reported as
staples of the Mexican diet, were lacking among the food items reported by the urban
children. Tortillas and beans were reportedly consumed by about 25% of the rural
children at breakfast, lunch and dinner, respectively.

The results of the comparisons of growth status, physical ﬁtness, daily
activities and diet of urban and rural primary school children reﬂect, to a large
extent, the contrast of living conditions and access to resources in the respectively
communities. Conditions in the colonia, though somewhat marginal, are closely
related to the economic and social resources of the city of Oaxaca. These include
access to jobs, better salaries, health care facilities, educational opportunities, and so
on, all factors which are related to the improved growth status of children.
Conversely, the increased prevalence of overweight in the urban compared to the
rural community suggests a negative consequence of urban life, perhaps reﬂecting
reduced physical activity and chronically excessive energy intake in contrast to a
more physically active lifestyle among the rural children. Conditions in the rural
community, though improving, reﬂect some degree of isolation from urban resources,
speciﬁcally related to income and educational opportunities. Financial input from

emigrants living in the Federal District or abroad has contributed to improved

115

infrastructures related to health and quality of life in the rural community. However,
the growth status of the current samples of urban and rural children has improved
compared to the status of school children in earlier studies in the two communities

about 30 years earlier (Malina, 2002).

116

TABLES

117

Table 1.1. Demographic, Economic, Education and Health Indicators for the State of

Oaxaca relative to national statistics. Estimates are for 1999 or 2000. The rank

(from highest to lowest) of the state of Oaxaca among the 32 federal entities is also

indicated where available.‘

 

 

Indicator National Oaxaca Rank
Loam
Population 94.48 million 3.44 million 10
Population Growth Rate 1.85% 1.32% 32
In—migrants 4.4% 2.7%
Out-migrants 4.4% 4.9%
Population by Localities:
<2500 inhabitants 25.4% 55.5% 1
215,000 inhabitants 61.0% 22.5% 32
Population by Age:
<15 years 33.4% 37.8% 3
265 years 4.9% 5.9% 4
Median Age 22 yrs 20 yrs 30
Economic
GDP/Total GDP 1.5% 19
GDP/capita 32
Minimum Wage 32pesos/day 30 pesos/day
Education
Illiteracy 9.5% 21.5% 3
Incomplete primary school 28.2% 45.1% 2
Post-primary school 51.8 33.3 31

 

118

Table 1.1 (continued)

 

 

Health

Death Rate/1000 population 4.5/1000 5.1/1000 3
Deaths, intestinal infections 5.7/1000 14.6/1000 2
Deaths, respiratory infections 17.0/1000 23.4/1000 4
Birth Rate/1000 population 21.7/1000 24.3/1000 6
Infant Mortality/1000 live born 13.8/1000 11.1/1000 24
Physicians/10,000 population 120/ 10,000 86/10,000 30
Insured Population 40.1% 22.6% 30

 

lBased on estimates reported by INEGI (2001a, 2001b) and Direccion General de

Estadistica e Inforrnatica de la Secretaria de Salud, Mexico (2001).

119

Table 2.1. Living conditions in the State of Oaxaca, 1980-2000.l

 

 

Indicator 1980 1990 2000
Population 2, 369,076 3, 019, 560 3,438,765
Urban population 32.0% 39.5% 43.0%
Rural population 68.0% 60.5% 57.0%
Birth rate 44.2* 35.3* 23.3*
Mortality rate 10.1* 6.5* 55*
Infant mortality rate 39.9" 23.5" 16.3"
Life expectancy, years 58.0 62.1 75.3
Illiteracy 35.9% 27.5% 20.0%
Sewage disposal 14.6% 29.9% 78.1%
Potable water 44.2% 58.1% 71.3%

 

'Data for 1980 and 1990 are from the XI Censo General de Poblacion y Vivienda

(INEGI, 1990); data for 2000 are from the 2000 census (INEGI, 2000).

*Births and deaths per 1000 inhabitants

**Per 1000 live born; the most recent estimate of infant mortality is based on records

for 1998. Speciﬁc information was lacking in the 2000 census.

120

Table 2.2. Mean weight (kg) and height (cm) for urban (Durango) and rural
(Morelos) children in Mexico in the 19603 by age group (years).‘

 

Age Weight (kg)
Group Durango Morelos U-R Diff

Height (cm)
Duran go Morelos U-R Diff

 

Boys
6+ 20.4 114.3
7+ 22.1 19.1 3.0 118.5 113.5 5.0
8+ 24.3 21.5 2.8 124.0 119.5 4.5
9+ 26.4 23.8 2.6 128.4 123.2 5.2
10+ 29.2 26.3 2.9 133.5 128.0 5.5
11+ 31.6 29.1 2.5 139.5 134.1 5.4
12+ 34.9 31.4 3.5 145.5 138.5 7.0
Girls
6+ 19.8 113.9
7+ 21.2 20.2 1.0 118.3 115.3 3.0
8+ 23.6 21.5 2.1 123.4 119.0 4.4
9+ 26.2 23.9 2.3 128.5 123.4 5.1
10+ 28.9 26.9 2.0 137.0 129.2 7.8
11+ 31.6 30.8 0.8 139.9 136.0 3.9
12+ 37.2 33.9 3.3 145.0 141.7 3.3

 

'Adapted fromVega-Franco and Robles-De la Vega (1962) and Perez-Ortiz and Mora

(1967) for Durango and Morales, respectively.

121

Table 2.3. Socioeconomic variation in the weight (kg) and height (cm) of urban boys
in the Federal District and corresponding data for low socioeconomic status rura1

boys from a community close to the Federal District by age group (years).l

 

Socioeconomic Status
Age Urban Urban Rural
Group High Medium Low Difference

Medium-Low

 

Weight (kg)

7+ 23.9 19.5 19.0 0.5
8+ 26.3 23.1 21.1 2.0
9+ 29.5 26.3 23.1 3.2
10+ 32.9 28.2 25.2 3.0
11+ 36.6 30.2 28.2 2.0
12+ 38.7 33.7 30.4 3.3
13+ 45.2 38.6 33.8 4.8
14+ 50.6 42.2 40.9 1.3
Height (cm) .
7+ 122.5 115.6 113.0 2.6
8+ 127.8 120.7 117.6 3.1
9+ 132.2 127.1 121.9 5.2
10+ 137.6 130.4 126.3 4.1
11+ 142.3 134.7 132.7 2.0
12+ 146.7 140.5 136.3 4.2
13+ 154.0 147.8 141.7 6.1
14+ 160.9 153.0 151.6 1.4

 

'Adapted from Perez-Hidalgo et al.(1965).

122

Table 2.4. Socioeconomic variation in the weight (kg) and height (cm) of urban boys

and girls in the Federal District by age group (years).l

 

 

Age Weight Height
Group High SES Low SES Diff High SES Low SES Diff
Boys
6-7 22.9 20.9 2.0 120.4 116.2 4.2
7-8 25.8 23.2 2.6 125.0 121.0 4.0
8-9 29.0 25.7 3.3 131.8 126.1 5.7
9-10 30.8 30.1 0.7 135.3 131.8 3.5
10-11 37.7 31.2 6.5 141.3 135.9 5.4
11-12 41.2 38.2 3.0 148.4 142.7 5.7
Girls
6-7 22.6 20.4 2.2 120.9 115.7 5.2
7-8 24.5 22.8 1.7 125.0 120.7 4.3
8—9 28.4 26.3 2.1 131.3 126.7 4.6
9-10 30.5 27.9 2.6 135.1 130.5 4.6
10-11 35.5 32.0 3.5 142.9 136.6 6.3
11-12 36.9 35.7 1.2 145.3 141.9 3.4

 

1Adapted from Villanueva (1979).

123

Table 2.5. Mean weight (kg) and height (cm) of indigenous Tojolabal children from

Chiapas by age group (years).

 

 

Age

Group Weight Diffl Height Diff2

Boys
6+ 16.5 3.2 104.2 8.6
7+ 18.1 4.4 107.9 11.1
8+ 18.7 6.7 113.0 11.9
9+ 21.2 7.4 117.4 12.5
10+ 29.9 1.2 119.6 14.8
11+ 26.3 7.8 125.3 13.9
12+ 29.5 7.5 127.8 15.5
13+ 31.8 12.5 134.1 18.2
14+ 35.4 135.7
15+ 39.3 141.6

Girls
6+ 17.2 2.2 103.1 8.0
7+ 18.0 3.8 107.1 10.0
8+ 19.9 4.4 110.0 12.4
9+ 21.7 5.2 115.6 12.3
10+ 22.8 7.9 118.8 14.6
11+ 25.4 8.8 125.2 13.8
12+ 26.7 11.8 130.1 16.2
13+ 30.9 14.9 133.6 18.3
14+ 33.9 136.2
15+ 37.7 141.6

 

'Adapted from Arechiga and Serrano (1981).

2The difference refers to the growth status of indigenous children relative to reference

values for urban children in the Federal District (Faulhaber, 1976).

124

Table 2.6. Mean height (cm) of a sample of indigenous Otomi children and a sample

of urban middle class children by age group (years).‘

 

 

Males Females
Group Otomi Urban Diff Otomi Urban Diff
6+ 106.4 112.8 6.4 107.1 111.1 4.0
7+ 111.3 118.9 7.6 111.9 117.1 5.2
8+ 117.9 124.9 7.0 117.2 122.4 5.2
9+ 121.8 130.0 8.2 121.6 127.9 6.3
10+ 125.2 134.3 9.0 126.0 133.4 7.4
11+ 130.2 139.2 9.0 131.2 138.9 7.7
12+ 134.8 143.3 8.5 134.8 146.3 11.5
13+ 136.8 152.3 15.5 141.5 151.9 10.4

 

1Adapted from Lagunas-Rodriguez and Jimenez-Ovando (1995)

125

Table 3.1. Population distribution of Santo Tomas Mazaltepec by age group and sex

 

 

in 2000.1
Age Group, yrs Males Females Total
0-4 100 109 209
5-9 138 150 288
10-14 127 146 273
15-19 94 119 213
20-24 48 70 118
25-29 59 89 148
30-34 48 70 118
35-39 56 73 129
40-44 49 51 100
45-49 38 56 94
50-54 36 36 72
55-59 29 28 37
60-64 31 28 59
65+ 90 78 168
Total 943 1 103 2046

 

lAdapted from the community health report for Santo Tomas Mazaltepec for 2001.

126

Table 3.2. Indicators of social, economic, educational and health conditions in the
rural and urban communities with comparative data for the city of Oaxaca and the

state of Oaxaca based on the national census for 2000.‘

 

 

Santo Tomas San Juan City of State of
(rural) (urban) Oaxaca Oaxaca

Total population 1,939 16,279 256,130 3.4 million
Household Characteristics:
Number of households 422 3,782 60,612 741,005
Sewage connected to street 1% 77% 78% 26%
Sewage to septic tank 14% 5% 6% 20%
No sewage installation 84% 18% 14% 54%
Radio 82% 90% 91% 71%
Television 71% 87% 89% 57%
Refrigerator 29% 61 % 72% 37%
Male head of household 85% 73% 70% 77%
Female head of household 15% 27% 30% 22%
Income 1% EAP):
< 1 minimum wage 15% 15% 12% 20%
1 to 2 minimum wages 16% 29% 25% 24%
2 to 5 minimum wages 15% 34% 28% 18%
No wages 49% 6% 4% 28%
Health and Education:
Insured population 6% 39% 48% 23%
Uninsured population 93% 59% 50% 76%
Number children/woman 3.1 2.2 1.9 2.1
Literate, 15+ years 91% 91% 94% 78%
Illiterate, 15+ years 9% 9% 5% 20%
Years of schooling 6 yrs 8 yrs 10 yrs 6 yrs
Did not complete primaria 22% 14% 11% 25%

 

'Adapted from INEGI (2002)

127

. EAP = economically active population.

Table 3.3. Numbers of school children surveyed in the rural and urban communities,

1999-2000, by age group and sex.

 

 

Age Males Females
Group* Rural Urban Rural Urban
6 26 30 29 24
7 26 29 22 27
8 30 26 37 23
9 31 25 25 33
10 26 31 28 25
1 l 15 20 34 25
12 9 10 4 7
13 14 2 5 2
l4 2 1 - -
15 1 1 3 -
Total 180 175 187 166

 

*Age groups are whole year categories, i.e., 6 = 6.00 to 6.99 years, 7 = 7.00 to 7.99

years, etc.

128

Table 3.4. Intra-observer technical errors of measurement for anthropometric

 

 

dimensions.

Present Study Buschang (1980)
Dimension (n=36, one month apart) (n=40, within day)
Weight 0.52 kg
Height 0.32 cm 0.33 cm
Sitting Height 0.40 0.47
Biacromial br. 0.23 0.32
Bicristal br. 0.35 0.38
Bicondylar br. 0.12 0.13
Biepicondylar br. 0.09 0.12
Arm circ., rel. 0.29 0.21
Arm circ., ﬂex. 0.29
Calf circ. 0.21 0.19
Triceps skf. 0.83 mm 0.33 mm
Subscapular skf. 0.67 0.33
Suprailiac skf. 0.69 0.33
Medial calf skf. 0.63

 

129

Table 3.5. Within day reliabilities for physical ﬁtness items based in intraclass
correlations derived from repeated measures ANCOVA with age as the covariate,

sexes and rural and urban samples combined.

 

 

Age Group
Test Item 6—9 10—13 6—13
Right Grip 0.90 0.94 0.92
Left Grip 0.92 0.95 0.94
Sit and Reach 0.93 0.94 0.93
Standing Long Jump 0.91 0.93 0.92
35 Yard Dash 0.85 0.87 0.86

 

130

Table 3.6. Within day reliabilities for physical ﬁtness items based on correlations

between trials, rural and urban samples combined.‘

 

 

Test Items
Right Left Sit and 35 Yard Standing
Grip Grip Reach Dash Long Jump
Boys
6-7 .81 .86 .82 .77 .88
8-9 .88 .90 .89 .83 .89
10-11 .91 .91 .90 .83 .91
12+ .87 .93 .92 .71 .89
Girls
6-7 .81 .85 .84 .86 .88
8-9 .88 .86 .92 .84 .88
10-11 .91 ' .90 .91 .84 .92
12+ .91 .90 .91 .93 .92

 

lCorrelations were calculated between trial 1 and trial 2, trial 2 and trial 3, etc., and

between best trial and second best, etc.

131

Table 3.7. Sample sizes by age group and sex, and means and standard deviations for

chronological age for the rural and urban children included in the analysis.

 

 

Age Rural Urban

Group n Mean SD 11 Mean SD
Boys

6 26 6.6 0.3 30 6.5 0.3

7 26 7.5 0.3 29 7.5 0.3

8 30 8.6 0.3 26 8.4 0.3

9 31 9.5 0.3 25 9.6 0.3

10 26 10.4 0.3 31 10.5 0.3

11 15 11.4 0.3 20 11.4 0.3

12 9 12.4 0.3 10 12.4 0.2

13 14 13.4 0.3 2 13.8 -

Girls

6 29 6.5 0.3 24 6.6 0.3

7 22 , 7.4 0.3 27 7.5 0.3

8 37 8.6 0.3 23 8.5 0.3

9 25 9.4 0.3 33 9.5 0.3

10 28 10.5 0.3 25 10.5 0.3

11 34 11.5 0.3 25 11.5 0.3

12 4 12.6 0.3 7 12.3 0.1

13 5 13.6 0.2 2 13.3 -

 

Age groups are whole year categories, i.e., 6 = 6.00 to 6.99 years, 7 = 7.00 to 7.99

years, etc.

132

Table 3.8. Status quo menarcheal status of girls 9-15 years of age in the rural and

urban communities.

 

 

Age Rural Urban
Group n 11 No n Yes n n No n Yes
9 25 25 0 33 33 0
10 28 28 0 25 25 0
11 33 32 1 25 24 1
l2 4 2 2 7 4 3
13 5 2 3 2 1 1
14 - - - - - -
15 3 1 2 . - - -

 

Information on menarcheal status was not available for one girl. There were no 14
year old girls in attendance-at school in each community at the time of the survey,
and there were no 15 year old girls in attendance at school in the urban community at

the time of the survey (see Table 3.2).

133

Table 4.1. Age-adjusted means and standard errors for indicators of body size and

proportions in rural and urban children 6-9 and 10-13 years of age.

 

Males 6-9 Years

Females 6-9 Years

 

 

 

Rural Urban Rural Urban
Variable Mean SE Mean SE p Mean SE Mean SE p
Weight, kg 23.4 0.3 24.5 0.3 <0.05 23.2 0.4 25.4 0.4 <0.001
Height, cm 119.1 0.5 121.4 0.5 <0.001 119.3 0.5 122.5 0.5 <0.001
BMI, kg/m2 16.4 0.2 16.5 0.2 NS 16.1 0.2 16.8 0.2 <0.01
Sit Ht, cm 65.3 0.3 66.4 0.3 <0.001 65.1 0.3 66.5 0.3 <0.001
Leg Lt, cm 53.8 0.3 54.9 0.3 <0.01 54.2 0.3 56.0 0.3 <0.001
St Ht/Ht, % 54.8 0.1 54.8 0.1 NS 54.6 0.1 54.3 0.1. NS

Males 6-9 Years Females 6-9 Years

Rural Urban Rural Urban
Variable Mean SE Mean SE p Mean SE Mean SE * p
Weight, kg 31.6 1.1 37.1 1.1 <0.001 32.8 0.8 35.2 0.9 <0.05
Height, cm 135.1 0.8 138.6 0.8 <0.01 135.1 0.7 138.8 0.8 <0.001
BMI, kg/m2 17.2 0.4 19.0 0.4 <0.001 17.8 0.3 18.0 0.3 NS
Sit Ht, cm 71.8 0.4 73.6 0.4 <0.05 72.2 0.4 73.7 0.5 <0.05
Leg Lt, cm 63.3 0.5 65.0 0.5 <0.05 62.9 0.4 65.1 0.5 <0.001
St Ht/Ht, % 53.2 0.1 53.2 0.1 NS 53.5 0.2 53.1 0.2 NS

 

Based on ANCOVA with age as the covariate. Sit Ht = Sitting Height, Leg Lt = Leg

Length, St Ht/Ht = Sitting Height/Height Ratio

134

Table 4.2. Age-adjusted means and standard errors for skeletal breadths and limb

circumferences in rural and urban children 6-9 and 10-13 years of age.

 

Males 6-9 Years

Females 6-9 Years

 

 

 

Rural Urban Rural Urban

Variable Mean SE Mean SE p Mean SE Mean SE p
Biacromial, cm 27.3 0.1 28.1 0.1 <0.001 27.2 0.1 28.2 0.1 <0.001
Bicristal, cm 19.6 0.1 20.2 0.1 <0.001 19.6 0.1 20.6: 0.1 <0.001
Biepicondylar, cm 4.8 0.0 4.8 0.0 NS 4.7 0.0 4.7 0.0 <0.05
Bicondylar, cm 7.5 0.0 7.7 0.0 <0.01 7.3 0.0 7.5 0.0 <0.001
Arm Circ, cm 17.6 0.2 17.8 0.2 NS 17.7 0.2 18.2 0.2 <0.05
Calf Circ, cm 23.7 0.2 24.3 0.2 <0.01 23.5 0.2 24.6 0.2 <0.001
EAMC, cm 15.2 0.1 15.4 0.1 NS 15.0 0.1 15.5 0.1 <0.01
ECMC, cm 21.2 0.1 21.7 0.1 =0.01 20.7 0.2 21.7 0.2 <0.001

Males 10-13 Years Females 10-13 Years

Rural Urban Rural Urban

Variable Mean SE Mean SE p Mean SE Mean SE p
Biacromial, cm 30.7 0.2 32.0 0.2 <0.001 30.9 0.2 31.6 0.3 <0.05
Bicristal, cm 21.6 0.2 23.4 0.2 <0.001 22.1 0.2 23.2 0.2 <0.001
Biepicondylar, cm 5.3 0.1 5.5 0.1 <0.01 5.2 0.0 5.2 0.1 NS
Bicondylar, cm 8.3 0.1 8.7 0.1 <0.01 8.1 0.1 8.1 0.1 NS
Arm Circ, cm 19.3 0.3 21.1 0.3 <0.001 20.2 0.2 20.6 0.3 NS
Calf Circ, cm 26.6 0.3 28.4 0.3 <0.001 27.0 0.3 27.7 0.3 NS
EAMC, cm 16.9 0.3 18.2 0.3 <0.01 17.1 0.2 17.7 0.2 NS
ECMC, cm 24.0 0.3 25.3 0.3 <0.01 23.5 0.2 24.4 0.2 NS

 

Based on ANCOVA with age as the covariate. Arm Circ - Arm Circumference, Calf

Circ = Calf Circumference, EAMC = Estimated Arm Muscle Circumference, ECMC

= Estimated Calf Muscle Circumference.

135

Table 4.3. Age-adjusted means and standard errors for subcutaneous fatness and

relative subcutaneous fat distribution in rural and urban children 6-9 and 10-13 years

 

 

 

 

ofage.
Males 6-9 Years Females 6-9 Years

Rural Urban Rural Urban
Variable Mean SE Mean SE p Mean SE Mean SE p
Triceps, mm 7.6 0.2 7.8 0.2 NS 8.7 0.2 8.5 0.2 NS
Subscapular mm 6.4 0.2 6.4 0.2 NS 7.7 0.3 7.9 0.3 NS
Suprailiac, mm 8.3 0.3 8.9 0.3 NS 9.4 0.3 9.6 0.3 NS
Medial Calf, mm 7.8 0.2 8.1 0.2 NS 9.0 0.2 9.0 0.2 NS
Sum 4 Skf, mm 30.1 0.7 31.2 0.7 NS 34.8 0.8 35.1 0.9 NS
TER, % 94.9 1.8 96.5 1.9 NS 95.6 1.8 99.1 1.9 NS

Males 10-13 Years Females 10-13 Years

Rural Urban Rural Urban
Variable Mean SE Mean SE p Mean SE Mean SE p
Triceps, mm 7.7 0.3 9.2 0.3 <0.01 9.9 0.3 9.3 0.3 NS
Subscapular, mm 7.4 0.4 9.2 0.4 <0.01 10.1 0.4 9.4 0.4 NS
Suprailiac, mm 8.8 0.5 11.9 0.5 <0.001 12.2 0.4 11.6 0.4 NS
Medial Calf, mm 8.1 0.3 9.7 0.3 <0.01 10.9 0.3 10.3 0.3 NS
Sum 4 Skf, mm 32.0 1.4 40.0 1.4 <0.001 43.2 1.1 40.7 1.2 NS
TER, % 102.0 3.0 110.8 3.0 <0.05 107.0 2.3 107.3 2.5 NS

 

Based on ANCOVA with age as the covariate. Sum 4 Skf — Sum of the four

skinfolds, TER = Trunk/Extremity Ratio (sum of the two trunk skinfolds/sum of the

two extremity skinfolds)

136

Table 4.4. Age-adjusted means and standard errors for indicators of muscular

strength in rural and urban children 6-9 and 10-13 years of age.

 

Males 6-9 Years

Females 6-9 Years

 

 

 

Rural Urban Rural Urban
Variable Mean SE Mean SE p Mean SE Mean SE p
R Grip, kg 11.8 0.2 11.9 0.2 NS 11.1 0.2 11.3 0.2 NS
L Grip, kg 11.0 0.2 11.5 0.2 NS 10.1 0.2 10.5 0.2 NS
Sum RL, kg 22.8 0.4 23.4 0.4 NS 21.2 0.4 21.7 0.4 NS
Sum/Wt, kg/kg 0.98 0.02 0.96 0.02 NS 0.92 0.01 0.86 0.01 <0.01

Males 10-13 Years Females 10-13

Rural Urban Rural Urban
Variable Mean SE Mean SE p Mean SE Mean SE p
R Grip, kg 18.5 0.5 19.0 0.5 NS 17.2 0.4 17.1 0.4 NS
L Grip, kg 17.1 0.5 18.2 0.5 NS 15.6 0.4 16.2 0.4 NS
Sum RL, kg 35.6 1.0 37.2 1.0 NS 32.8 0.7 33.3 0.7 NS
Sum/Wt, kg/kg 1.13 0.02 1.02 0.02 <0.001 1.01 0.02 0.96 0.02 NS

 

Based on ANCOVA with age as the covariate. R Grip = Right Grip, L Grip = Left

Grip, Sum RL = Sum of Right and Left Grip, Sum/W t = Sum of Right and Left Grip/

Body Weight.

137

Table 4.5. Age-adjusted means and standard errors for indicators of physical ﬁtness

in rural and urban children 6-9 and 10-13 years of age.

 

Males 6-9 Years

Females 6-9 Years

 

 

 

Rural Urban Rural Urban
Variable Mean SE Mean SE p Mean SE Mean SE p
SAR, cm 26.3 3.9 28.0 4.0 <0.01 27.1 4.2 27.8 4.4 NS
Sit-Up, n 7.5 0.4 11.3 0.4 <0.001 6.4 0.4 9.4 0.4 <0.001
SLJ, cm 90.3 1.7 106.2 1.7 <0.001 78.9 1.7 91.7 1.8 <0.001
Dash, sec 7.34 0.05 7.47 0.05 NS 7.94 0.06 8.13 0.07 <0.05
Dis Run, m 1195 14 1085 15 <0.001 1123 15 1039 16 <0.001
Males 10-13 Years Females 10-13 Years
Rural Urban Rural Urban
Variable Mean SE Mean SE p Mean SE Mean SE p
SAR, cm 27.0 6.5 26.9 6.6 NS 26.6 5.8 28.8 6.3 =0.01
Sit-Up, n 12.1 0.5 14.1 0.5 <0.01 8.1 0.5 11.2 0.6 <0.001
SLJ, cm 111.8 2.5 130.4 2.5 <0.001 90.1 1.8 109.9 2.0 <0.001
Dash, sec 6.66 0.06 6.47 0.06 <0.05 7.26 0.07 6.95 0.07 <0.01
Dis Run, m 1856 27 1828 26 NS 1637 23 1703 25 =0.05

 

Based on ANCOVA with age as the covariate. SAR = Sit and Reach; Sit-Up =

Number of sit-ups completed in 30 seconds, SLJ = Standing Long Jump, Dash = 35

yard dash (32.3 meters), Dis Run = Distance run in 8 minutes in children in Grades

1-3 and in 12 minutes in children in Grades 4-6; ages approximate 6-9 in the former

and 10-13 in the latter (see text).

138

Table 4.6. Prevalence [95% conﬁdence intervals] of stunting in rural and urban

children 6-13 years of age.

 

 

Age Rural Urban
Group n f % [95% CI] n f % [95% CI]
Males
6—9 113 31 27.4 [19.2 - 35.6] 110 14 12.7 [6.5 — 18.9]
10-13 64 20 31.3 [19.8 — 42.6] 63 11 17.5 [8.1 — 26.9]
6-13 177 51 28.8 [22.1 — 35.5] 173 25 14.5 [9.3 — 19.7]
Females
6-9 113 33 29.2 [20.8 — 37.6] 107 16 14.9 [8.2 — 21.8]
10-13 71 21 29.6 [19.0 — 40.2] 59 10 16.9 [7.3 — 26.5]
6-13 184 54 29.3 [22.7 — 35.9] 166 26 15.7 [10.2 - 21.2]

 

Stunting was deﬁned as a height below two standard deviations of age and sex

speciﬁc reference data for healthy children (Centers for Disease Control and

Prevention, 2000).

139

Table 4.7. Prevalence [95% conﬁdence intervals] of wasting in rural and urban

children 6-13 years of age based on the body mass index.

 

 

n f % [95% CI]
Males:
Rural 177 4 2.3 [0.01 — 4.5]
Urban 173 2 1.2 [-0.4 — 2.8]
Females:
Rural 184 4 2.2 [0.0 — 4.4]
Urban 166 2 1.2 [-0.5 — 2.9]

 

Wasting was deﬁned as a BMI <5‘“ percentiles (age and sex speciﬁc) of the United

States growth charts (Centers for Disease Control and Prevention, 2000).

140

Table 4.8. Prevalence [95% conﬁdence intervals] of overweight and obesity, using

intematonal criteria, in rural and urban males 6-13 years of age based on the body

 

 

mass index.
Overweight Obese Total
n f % [95% CI] f % [95% CI] f % [95% CI]
Males:
Rural
6-9 113 7 6.2 [1.8 —10.6] 2 1.8 {-0.6 —4.2] 9 8.0 [3.0—13.0]

C

10-13 64 2 3.1[-1.2-7.4] 0 2 3.1[-1.1—7.4]
6-13 177 9 5.1[1.9—s.3] 2 1.1[-0.5—2.7] 11 6.2[2.6—9.8]

Urban

6-9 110 10 9.1 [3.7 — 14.5] 2 1.8 [-0.7 — 4.3] 12 10.9 [5.1 — 16.7]
10-13 63 9 14.3 [5.7 — 22.9] 7.9 [1.2 - 14.6] 14 22.2 [11.9 — 32.5]
6-13 173 19 11.0 [6.3 —15.7] 7 4.0 [1.1— 6.9] 26 15.0 [9.7 — 20.0]

L)! .

 

International criteria are those of Cole et a1. (2000). See text for the respective cut-off

points for overweight and obesity.

141

Table 4.9. Prevalence [95% conﬁdence intervals] of overweight and obesity, using

intematonal criteria, in rural and urban females 6-13 years of age based on the body

 

 

mass index.
Overweight Obese Total
n f % [95% CI] f % [95% CI] f % [95% CI]
Females:
Rural

6-9 113 3 7.1[2.4—11.3] 1 0.9[-0.s—4.5] 9 8.0 [3.0-13.0]
10-13 71 6 8.5 [2.0—15.0] 1 1.4[-1.3—4.1] 7 9.9 [3.0—16.8]
6-13 184 14 7.6 [3.8-11.4] 2 1.1 [-0.4—2.6] 16 8.7 [4.6— 12.8]

Urban
6-9 107 17 15.9 [9.0 — 22.8] 2 1.9 [-0.7 — 4.5] 19 17.8 [10.6 — 25.0]
10-13 59 7 11.9 [3.6 — 20.2] 2 3.4 [-1.2 — 8.0] 9 15.3 [6.6 — 24.5]
6-13 166 24 14.5 [9.1 --19.7] 4 2.4 [0.1- 9.1] 28 16.9 [11.2 - 22.6]

 

International criteria are those of Cole et a1. (2000). See text for the respective cut-

off points for overweight and obesity.

142

Table 4.10. Household activities reported by rural and urban school children in 4‘“,

5‘“ and 6‘“ grades: Frequencies reported and corresponding percentages.

 

 

Males Females
Rural Urban Rural Urban
(n=77) (n=83) (n=99) (n=77)
Activities f % f % f % f %
House-Related

House cleaning 32 42 56 67 66 67 48 62

Bed making 9 12 27 33 26 26 21 27

Cleaning dishes 1 1 19 23 59 60 40 52

Doing laundry 2 3 3 4 25 25 9 12
Food-Related

Cooking - 2 2 l4 l4 6 8

Making tortillas

Corn cleaning 8 10 - 18 18 -
Corn to mill - - 13 13 -
Prepare dough/

cook tortillas 2 3 - 33 33 -

Cut and gather wood 10 13 1 1 - -

Get water 9 12 - 6 6 -

Gather chapulines 1 2 - 4 4 -
Animal-Related

Care for animals‘ 54 70 - 8 8 -

Get feed from pasture2 53 69 - 9 9 -

Pet care/play - 7 8 - 2 3
Farm Activities3 3 4 - 2 2 -
Assist Family Business 3 4 2 2 12 12 -

Care for Siblings 1 1 2 2 7 7 2 3

 

‘Includes feeding animals, taking them to pasture (grazing, herding), milking cows
and goats, etc.
2Includes cutting and gathering of animal feed from pasture.

3Most commonly includes clearing ground.

143

Table 4.11. Recreational activities reported by rural and urban school children in 4‘“,

5‘“ and 6‘“ grades: Frequencies reported and corresponding percentages.

 

 

Males Females
Rural Urban Rural Urban
(n=77) (n=83) (n=99) (n=77)
Activities f % f % f % f %
Sports
Basketball 56 73 67 81 60 61 23 30
Football (soccer) 56 73 26 31 9 9 13 17
Volleyball 3 4 5 6 7 7 24 31
Basebakk - 9 11 - 4 5
Miscellaneous
Bicycling 3 5 4 2 2 3
Skating - 4 - 3 4
Karate - 3 - 1
Dancing 1 1 - l 1 -
Rope jumping - ' - 1 1 -
Games
Chase 8 10 29 35 47 47 45 58
Hide and seek 7 9 6 7 32 32 23 30
Others' - 1 1 - 3 4
Light/Sedentary
Play with toys
Cars/ marbles 10 13 2 2 1 1 -
Dolls - 2 2 9 9 15 20
Videogames 4 10 12 - 1 1
Music playing 2 - 2 2 -
Music listening - - 3 3 -
Table games2 - 4 5 - 7 9

 

‘Swing, matatena, rondas

2Dominos, chess

144

Table 4.12. Time spent viewing television (hours per day) reported by rural and
urban school children in 4‘“, 5‘“ and 6‘“ grades: Frequencies reported and

corresponding percentages.

 

 

Males Females

Rural Urban Rural Urban

(n=77) (n=83) (n=99) (n=77)
Activities f % f % f % f %
None or no TV‘ 10 13 7 8 11 11 9 12
S 1 hours 38 49 37 45 38 38 28 36
> 1 S 2 hours 19 25 16 19 27 27 19 25
>ZS3hours 7 9 12 15 13 13 13 17
>3hours 3 4 11 13 10 10 8 10

 

lNo television viewing reported or no television available at home; ncludes 8
children who did not complete this question; it was assumed that they did not have a

television at home(2 rural males, 1 rural female, 3 urban males, 2 urban females).

145

Table 4.13. Frequency of household-related activities before and after school by estimated

level of intensity reported by rural and urban 4‘“, 5‘“ and 6‘“ grade school children.

 

Males Rural (n=77) Urban (n=83)l
Before After Before After
Intensity f f f f
No activities 21 7 38 6
Very light 12 10 15 18
Light 4 12 29 40
Moderate 35 32 1 8
Moderate-to-vigorous 6 1 8 - -
Females Rural (n=99) Urban (n=77)‘
Before After Before After
Intensity f f f f
No activities 27 16 38 1
Very light 44 24 12 l 1
Light 3 26 20 54
Moderate 17 25 4 7
Moderate-to-vigorous 6 5 - -

 

‘Frequencies do not necessarily add to the total number because some children did not complete the

respective questions and some indicated multiple activities

Very light — includes activities involved in making the bed, doing dishes and running errands close to
home (and requiring a short period of time),

Light — includes housecleaning (sweeing, mopping), shucking corn, removing grains from cobs,
assisting with family business, cooking,

Moderate - includes feeding, cleaning and herding animals; milking cows/goats; washing clothers;
grinding corn; making, delivering and/or selling tortillas; gathering chapulines,
Moderate-to-vigorous - clearing farm ground, carrying water, cutting and gathering wood, cutting

and carrying feed for animals.

146

Table 4.14. Recreational activities reported by rural and urban 4‘“, 5‘“ and 6‘“ grade

children during the break period at schoolerequencies and corresponding

 

 

percentages.
Males Females

Rural Urban Rural Urban
(n=77) (n=80) (n=90) (n=73)
Activities f % f % f % f %
Eating, chatting, sitting 7 9 16 20 13 14 31 42
Walking - 1 1 - 2 3
Running, chasing 27 35 25 31 43 48 36 49
Basketball 40 52 8 10 34 38 2 3
Football (soccer) 3 4 3O 38 - 2 3

 

I47

Table 4.15. The total number of foods reported and the ten foods reported most often
at breakfast (dosaﬂno) by rural and urban children in the 4‘“, 5‘“ and 6‘“ grades -

percentages reporting consumption of each food item in the past 24 hours (sexes

 

 

 

combined).

Rural (n=67) Urban (n=97)l
Foods % Foods %
Total number of foods 25 Total number of foods 34
Ten most often consumed:
Bread 60 Bread 24
Chocolate 49 Milk 16
Milk 28 Coffee 13
Coffee 19 Chocolate 6
Tortillas l6 Cereal 6
Eggs 9 Milk shake 6
mLe 9 Atole 5
Atole 6 Eggs 5
Soft drink (refresco) 6 Orange juice 4
Fruit drink (agua frutas) 4 Beans 4
Beans 4 Pasta (noodle) soup 4
Chicken 4 Sausage (chorizo) 4
Meat (beef) 4
Cheese 4
Pasta (noodle) soup 4

 

l21 urban children did not report eating breakfast at home, but had their morning
meal during the school break. It basically included a sandwich made of some type of

meat, cheese or eggs and a drink (soft drink, juice or water).

148

Table 4.16. The total number of foods reported and the ten foods reported most often

at lunch (comida) by rural and urban children in the 4‘“, 5‘“ and 6‘“ grades -

 

percentages reporting consumption of each food item in the past 24 hours (sexes

 

 

 

 

combined).
Rural Urban

Foods % Foods %
Total number of foods 48 Total number of foods 44
Ten most often consumed:

Soft drink (refresco) 30 Chicken 14
Orange juice 22 Beans 12
Fruit drink (agua frutas) 18 Rice 12
Bread 16 Chicken broth 10
Tortillas 16 Eggs 10
Mixed sauce (salsa) ’ 16 Soft drink (refresco) 8
Memelitas‘ 15 Pasta (noodle) soup 8
Beans 9 Beef broth . 6
Tamales 7 Meat (beef) 5
Sandwich 7 Dried meat (_c_o_c_in_a/t_asajb) 5

 

‘A type of thick tortilla usually spread with beans and cheese with salsa on top.

149

Table 4.17. The total number of foods reported and the ten foods reported most often
at dinner (cena) by rural and urban children in the 4‘“, 5‘“ and 6‘“ grades - percentages

reporting consumption of each food item in the past 24 hours (sexes combined).

 

 

Rural Urban

Foods % Foods %
Total number of foods 23 Total number of foods 43
Ten most often consumed:

Tortillas 1 8 Coffee 24
Chicken broth 10 Milk 18
Bread 9 Bread 18
Coffee 7 Eggs 6
Beans 7 Chicken 5
Chocolate 6 Chocolate 4
Meat (beef) 6 Cereal 3
Chicken 6 Tortillas 3
Tamales 4 Beans 3
Meat broth 4 Rice 3
Mo]; 4

 

150

Table 5.1. Age-adjusted means and standard errors based on ANCOVA with age as

the covariate for indicators of body size in urban school children grouped by place

 

 

of birth.
Place of Birth
San Juan or Other Areas of Other States of
City of Oaxaca State of Oaxaca Mexico
(n=126, 128)l (n=29, 31) (n=15, 6)

Mean SE Mean SE Mean SE F p
Males
Height, cm 126.7 4.9 128.0 10.2 127.7 14.2 0.77 NS
Weight, kg 28.9 0.7 28.7 1.4 28.5 1.9 0.02 NS
BMI, kg/m2 17.6 0.2 17.1 0.5 17.2 0.7 0.50 NS
Females
Height, cm 128.7 5.3 128.0 10.7 127.3 24.3 0.27 NS
Weight, kg 29.5 0.5 27.9 1.1 28.2 2.4 1.00 NS
BMI, kg/m2 17.5 0.2 16.6 0.4 17.3 0.9 1.88 NS

 

'The ﬁrst number refers to the sample size for boys and the second to girls.

151

Table 5.2. Age-adjusted means and standard errors based on ANCOVA with age as

the covariate for indicators of body size in rural school children grouped by place of

 

 

 

birth.
Place of Birth
Other Areas of Other States of

Santo Tomas State of Oaxaca Mexico

(n=159, 155)‘ (n=5, 9) (n=10, 15)

Mean SE Mean SE Mean SE F p
Males
Height, cm 125.7 0.4 121.5 24.9 124.8 17.5 1.50 NS
Weight, kg 26.7 0.3 25.4 2 0 27.1 1.4 0.27 :NS
BMI, kg/m2 16.6 0.1 16.9 0.8 17.3 0.5 0.72 NS
Females
Height, cm 125.3 4.5 126.7 18.6 127.5 14.4 1.26 NS
Weight, kg 26.6 0.4 31.3 1.6 29.1 1.2 5.54 <.01
BMI, kg/m2 16.6 0.2 19.1 0.6 17.6 0.5 8.97 <.01

 

lThe ﬁrst number refers to the sample size for boys and the second to girls.

152

Table 5.3. Estimated prevalence (%) of overweight and obesity in primary school

children 6 to 13 years of age from several areas of Mexico.‘

 

 

n Overweight Obese Total
Males
Rural:
Oaxaca, Zapotec 177 5 1
Chihuahua, Tarahumara 308 4 1 5
Urban:
Oaxaca 173 11 4 15
Sonora 159 19 14 33
Veracruz 201 22 1 1 34
Mexico City 369 23 9 33
Females
Rural:
Oaxaca, Zapotec 184 8 1 9
Chihuahua, Tarahumara 273 0 8
Urban:
Oaxaca 166 14 2 17
Sonora 144 17 7 24
Veracruz 176 23 9 32
Mexico City 386 22 6 28

 

‘Based on the international criteria for overweight and obesity reported by Cole et a1.
(2000). The criteria were applied to individual data from Pei'ia Reyes et al. (in
preparation) Tarahumara school children in Chihuahua, from Peﬁa Reyes et al. (2002)
for children in Sonora and Veracruz, and from Siegel (1999) for children in Mexico

City to derive the prevalences.

153

Table 5.4. Estimated prevalence (%) of wasting in primary school children 6 to 13

years of age from several areas of Mexico.‘

 

 

Males Females
n % n %
Rural:
Oaxaca, Zapotec 177 2 184 2
Chihuahua, Tarahumara 308 <1 273 2
Urban:
Oaxaca 173 1 166 1
Sonora 159 2 144 3
Veracruz 201 3 176 3
Mexico City 369 6 386 4

 

‘Based on a BMI <5‘“ age- and sex-speciﬁc percentiles of the new United States

growth charts (Centers for Disease Control and Prevention, 2000). The criteria were

applied to individual data from Pefia Reyes et al. (in preparation) for Tarahumara

school children in Chihuahua, from Peﬁa Reyes et al. (2002) for children in Sonora

and Veracruz, and from Siegel (1999) for children in Mexico City to derive the

prevalences.

154

Table 5.5. Estimated prevalence (%) of growth stunting in primary school children6-

13 years of age by age group in Oaxaca and Chihuahua.‘

 

 

Males Females
n % n %
6-9 Years
Oaxaca
Urban 110 12.7 107 14.9
Rural, Zapotec 113 27.4 113 29.2
Chihuahua, Tarahumara 152 39.0 150 34.0
10-13 years
Oaxaca
Urban 63 17.5 59 16.9
Rural, Zapotec 64 31.3 71 29.6
Chihuahua, Tarahumara 158 23.0 123 33.0

 

‘Stunting is deﬁned as a z-score below —2.0 relative to age- and sex-speciﬁc
reference values for height (Centers for Disease Control and Prevention, 2000). The
criteria were applied to individual data from Peﬁa Reyes et al. (in preparation) for

Tarahumara school children in Chihuahua.

155

FIGURES

156

     
   

lxtlan

Santo Tomas'

Oaxaca City
(San Juan Chapultepec)

Tlacolula

Ir. ‘ a
now "’

 

Isthmus
of
Tehuantepec

o._\

Figure 3.1. Map of the Valley of Oaxaca, indicating the location of the

comunities studied Santo Tomas Malzatepec and San Juan Chapultepec.

157

cm Males

 

 

 

150 - Median
P 25

140 " P 10
P 5

130 "‘

120 4

I ‘0 ‘1 """.'""" Rural

" " 0" " Urban
‘00 I l l 1 l 1
() 7 8 9 10 l l 12
Age, years

Figure 4.1. Mean height of urban and rural boys
relative to selected percentiles of United States
reference date (Centers for Disease Control

and Promotion, 2000).

158

cm Females
160 a
Height
Median
150 — P 25
P 10
140 P 5

130"

120'“

 

 

 

”0‘ _.—" Rural
" '0" Urban

'00 I I f ﬁ I l
6 7 8 9 10 ll 12

Age, years

Figure 4.2. Mean height of urban and rural girls
relative to selected percentiles of United States
reference date (Centers for Disease Control

and Promotion, 2000).

159

kg

 

Males
45 -
Weight
Median
40 -
P 25
35 -
P 10
30 q P 5
25 -
20 - —0— Rural

" ‘ 0" " Urban

 

 

'5 I I I I I I
6 7 8 9 10 ll 12

Age, years

Figure 4.3. Mean weight of urban and rural boys
relative to selected percentiles of United States
reference date (Centers for Disease Control

and Promotion, 2000).

160

“3 Females
45 a

Weight

Median

 

 

 

P 25
P 10
P S
+ Rural
' ' 0‘ ' Urban
‘5 I I I I I I
6 7 8 9 10 11 12
Age, years

Figure 4.4 Mean weight of urban and rural girls
relative to selected percentiles of United States
reference date (Centers for Disease Control

and Promotion, 2000).

161,

kg/m

2 Males
21 T

20"]

Body Mass Index

P75

Median

P25

 

‘5 ‘ —.— Rural

- - O- - Urban

 

 

I I I I ﬂ I
6 7 8 9 10 11 12

Age, years

Figure 4.5. Mean body mass index of urban and

rural boys relative to selected percentiles of

Un

ited States reference date (Centers for Disease

Control and Promotion, 2000).

162

kg/m2 Females
21 -'

Body Mass Index

P75

Median

P25

 

+ Rural

"0" Urban
f I
8 9 10 ll 12

 

I;
\l—i
--1

Figure 4.6. Mean body mass index of urban and
rural girls relative to selected percentiles of
United States reference date (Centers for Disease

Control and Promotion, 2000).

163

cm Males
145 -

Height
140d
135-
130-
125-1

120-

115-

 

 

 

110 l l l l l l

C‘“ Females
145 -

Height
140-
135-
130-
125-

120-

115-

 

 

 

‘10 l l l l l 1
6 7 s 9 10 11 12

Age, years

Figure 4.7. Mean height of urban and rural

children.

164

kg Males

 

 

 

40-
Weight
35—
3O]
25-
20-
' ' ' ' ' Urban

‘5 I I I F I I

6 7 8 9 10 11 12

kg Females

 

 

 

40-
Weight
35-
30—
25-
20-
" ' ' ' " Urban

‘5 I I I I I I

6 7 8 9 10 11 12

Age, years

Figure 4.8. Mean weight of urban and rural

children.

165

kg/m2 Males

 

 

 

 

 

 

 

20 -
Body Mass Index
4
l \
19 - I \
I \
I \
' \
, \
18 " 'l ‘\
I
l
I
l7 -1 [If
I - - - - I.
Q 1’
J-ﬁ-T'
l6 -
Rural
‘5 I I I I ﬂ I
6 8 9 10 l l 12
Age, years
kg/m2 Females
20 -
Body Mass Index
19 -
18 -
17 -
16 -
‘5 r I I F I 1
6 7 8 9 10 1 1 12
Age, years

Figure 4.9. Mean body mass index of urban

and rural children.

166

CIT]

75-
70-1
65-
60-
551
50"“

45

Males

Sitting Height

 

 

 

cm

75

60-

55-

50-

Age, years

Females

Sitting Height

 

— Rural
----- Urban

 

 

45

I I I l l I

8 9 10 11 12

Age, years

Figure 4.10. Mean sitting height and estimated

leg length of urban and rural children.

167

% Males

 

 

 

 

 

 

6O -
Sitting Height/Height Ratio
58 —
Rural
----- Urban
56 ﬁ
54 -
52 -1
50 I I I I I I
6 7 8 9 10 l l 12
Age, years
% Females
6O -
Sitting Height/Height Ratio
58 -
Rural
""" Urban
56 -
54 -
l
52 -
50 I I I I I I
6 7 8 9 10 1 1 12

Age, years

Figure 4.11. Mean sitting height/standing

height ratio of urban and rural children.

168

cm

35 Males - Skeletal Breadths

Biacromial

 

 

 

 

 
 
   

 

 

 

12
CIT]
35 Females — Skeletal Breadths
Biacromial
30 d
l
25 -
Bicristal o ' '
20 _' ‘ — a
Rural
----- Urban
I 5 I l l l l l
6 8 9 10 ll 12

Figure 4.12. Mean biacromial and bicristal

breadths of urban and rural children.

169

cm

Males - Skeletal Breadths

 
   

 

 

 

Bicondylar ’ - - .. -
I
8 ..
7 ._
Rural
----- Urban
6 _
Biepicondylar
’ ’ I - n - .
5 - /
4 I I I I I I
6 7 8 9 10 ll 12

cm Females — Skeletal Breadths

 

 

 

 

 

Bicondylar
3 _.
7 .J
l
6 _
Biepicondylar
5 _
4 I I I I I I
6 7 8 9 10 ll 12

Figure 4.13. Mean bicondylar and
biepicondylar breadths of urban and rural

children.

170

crn . .
Males - leb Circumferences

 

 

 

,
Calf
25 -
20 -
15 f T T l l l
6 7 8 9 10 l l 12
Age, years
cm

Females - Limb Circumferences
Calf

 

 

 

 

15 l I 1 I l 1

Age, years

Figure 4.14. Mean arm and calf

circumferences of urban and rural children.

171

cm Males - Estimated Limb Muscle Circumferences

 

 

 

30-
1f

25_ Ca

204

15—

10 l l l l l l

6 8 9 10 ll 12
Age, years

cm

Females - Estimated Limb Muscle Circumferences

 

 

 

10 I I

Age, years

Figure 4.15. Mean estimated arm and calf muscle

circumferences of urban and rural children.

172

mm

Males - Skinfolds

l3 _ Triceps
12 -

11‘

10-

 

 

mrn

'4 ‘ Females - Skinfolds
13 _ Triceps

12 - —— Rural

1 l A i """ Urban

10%

gl

 

 

LII

 

I I I I
6 7 8 9 10 11 12

Age, years

Figure 4.16 Mean triceps skinfold thicknesses

of urban and rural children.

173

Males - Skinfolds

 

 

1
13 _ Subscapular
12 _. Rural
11 - ----- Urban
10 1
I‘
\
9 d ” s‘
I \
8 -I x ‘
I
7 d M
I
I
6 - ~ - n ’
5 I I I I I I
6 7 8 9 10 ll 12
Age, years
m1? Females - Skinfolds
l3 - Subscapular
12 -i — Rural

----- Urban

ll-

10-

 

 

 

5 l l l l l l
6 7 8 9 10 11 12

Age, years

Figure 4.17. Mean subscapular skinfold

thicknesses of urban and rural children.

174

mm

4 Males - Skinfolds

 

 

 

 

 

13 _ Suprailiac
\
12 ~ ,’ x
I s‘
11 _ II .
I
10 ‘ I,
- - ‘ - ’
9 - ”'
I
u - - - I
8 - f/K
7 -
Rural
6 - """ Urban
5 I I I I I I
6 7 8 9 10 11 12
Age, years
mt: Females - Skinfolds

13 _ Suprailiac
12 A
ll ..
lO -

9 —.

8 _

7 1

Rural
6 - """ Urban
5 I I I I I I
6 7 8 9 10 11 12

Figure 4.18. Mean suprailiac skinfold

thicknesses of urban and rural children.

175

mm
l4-

13-

12-

11-

Males - Skinfolds

Medial Calf

 

 

mm

H

13-

12-

r I I I If I
7 8 9 10 ll 12

Age, years

Females - Skinfolds

Medial Calf

 

 

 

 

8 9 10 ll 12

Figure 4.19. Mean medial calf skinfold

thicknesses of urban and rural children.

176

mm

5 Males - Skinfolds

 

 

 

 

 

 

Sum of Four Skinfolds
40 -
35 -
3O -
25 I I I I I I
6 7 8 9 10 ll 12
Age, years
mm Females - Skinfolds
Sum of Four Skinfolds
40 -I
|
35 .4
30 ﬂ Rural
""" Urban
25 I I I I I I
6 7 8 9 10 ll 12

Age, years

Figure 4.20. Mean sum of skinfold

thicknesses of urban and rural children.

177

mm/mm
1.2 - Males - Trunk Extremity Ratio

 

 

 

mm/mm

1.2 — Females - Trunk Extremity Ratio

1.1—

0.9 ..

 

 

 

0'8 I 1 I l I ' I

Figure 4.21. Mean trunk/extremity skinfold

ratios of urban and rural children.

178

kg
20-
19-
18-
1H
l6-l
151
l4-
13-
12-
11-
10-
9....
8+
7

Males

Right Grip

 

 

 

kg
20-
19-
18-
17-
16-
15-
14-
13-
12-
11-
10-
9—
8—

Females

Right Grip

 

 

 

Figure 4.22. Mean right grip strength of

urban and rural children.

179

kg
20-
19-
18-
17-
16-
15-
14-
13-
12-
11-
10-
9..
8..

Males
Left Grip

 

 

 

kg
19-
18-
17-
16d
15-
14-
134
12-
11—
10-
9-
3-

Females

Left Grip

 

 

 

I I I I I 1
7 8 9 10 11 12

Age, years

Figure 4.23. Mean left grip strength of

urban and rural children.

180

kg

 

 

 

 

 

 

Males
40
Sum Right + Left Grip
35 -
3O -
25 -
20 -
15 I F I I I I
6 7 8 9 10 ll 12
Age, years
kg {Females
4O -
Sum R+L Grip
35 -
3O -
25 #
20 -
15 I I I I I I
6 7 8 9 10 11 12

Figure 4.24. Mean sum of right and left grip

of urban and rural children.

181

kg/kg Males
1 .2 1

Sum R+L Grip/Weight

 

 

 

0-9'1
0.8 _ _ Rural
""" Rural
0-7 I I 1 I I I
6 7 8 9 10 11 12

kg/kg Females
1 .2 -
Sum R+L Grip/Weight

 

 

 

 

0.9-

0.8-

0'7 l l l l l l
6 7 8 9 IO 11 12

Figure 4.25. Mean grip strength (sum of
right and left) per unit body weight in

urban and rural children.

182

cm Males
3 0 -

Sit and Reach

 

 

 

 

Age, years

cm Females
0 _

Sit and Reach
29 —

28—
27-
26—

25-

 

 

 

Figure 4.26. Mean sit-and-reach of urban

and rural children.

183

 

 

 

4 I I I I T I
6 7 8 9 10 11 12
Age, years
1]
Females

15 -

14 _ Sit-ups

13 -

12 —

ll-
10-

 

 

 

4 I I I I I I
6 7 8 9 10 11 12

Age, years

Figure 4.27. Mean timed sit-ups in urban

and rural children.

184

cm Males
140 -

Standing Long Jump
130 -1
120 -
110 -
100 -

90-

80—

 

70—

 

 

60 I I f I I I

cm
140-

Females

Standing Long Jump
130 -

120-1
110-

100-

 

90-

80-

70-

 

60

 

 

Figure 4.28. Mean standing long jump

performance of urban and rural children.

185

sec Males
Dash

 

 

 

 

 

 

 

""" Urban
9 T I I T I
6 7 8 9 10 1 1 12
Age, years
see Females
6 —
Dash
7 _
8 —.
9 I I I I I
6 7 8 9 10 11 12
Age, years

Figure 4.29. Mean 35-yard dash performance of

urban and rural children.

186

meters

 

 

 

 

 

 

2400 - Males
Distance Run
2100 -
1800 - ' '
1500 -
1200 - /
_ _ - . Rural
’ ‘ ’ ----- Urban
900 I I I I I I 1
6 7 8 9 10 l l 12 13
Age, years
meters
2400 q Females
Distance Run
2100 -
l 800 -1
kg—r/
1500 -
1200 -
\A ° Rural
'¢" ----- Umm
900 I I I I I I
6 7 8 9 10 l l l 2
Age, years

Figure 4.30. Mean distance run in 8 minutes

(grades 1-3) and in 12 minutes (grades 4-6) by

urban and rural children.

187

APPENDICES

188

APPENDIX I

UNIVERSITY COMMITTEE FOR RESEARCH INVOLVING HUMAN

SUBJECTS

AT MICHIGAN STATE UNIVERSITY

APPROVAL FORMS

189

 

OFFICE OF
RESEARCH
AND
GRADUATE
STUDIES

University Committee on
Research Involving
Human Sub]
(UCIIIHS)

Michigan State University
246 Administration Building
East Lansing. Michigan
48824-1046

517/355-2180
FAX: 517/432-1171

”MMM@MQMMmey
masmwmmmnwmy
emwmwmmmm

mwsamewwamm
wwwmmmmnmwmm

MICHIGAN STATE

Ll hi I V’ E II S I I" Y

 

April 14, 1998

TO: Robert M. Malina
213 IM Sports Circle

RE: IRB#: 98-118
TITLE: SECULAR CHANGE IN SIZE, STRENGTH AND MOTOR
FITNESS IN THE VALLEY OF OAXACA, MEXICO
REVISION REQUESTED: N/A
CATEGORY: FULL REVIEW
APPROVAL DATE: 04/06/98

The university Committee on Research Involving Human Subjects'(UCRIHS)
review of this project is complete.. I am pleased to adVise that the
rights and welfare of the human subjects appear to be adequately
rotected and methods to obtain informed consent are appropriate.
gherefore, the UCRIHS approved this progect and any revisions listed
above.
ONE REVIEWER SUGGESTS REVISING THE CONSENT FORM LANGUAGE REGARDING
REMOVAL OF CLOTHING TO "ONLY SHOES AND OUTER CLOTHES LIKE JACKETS 8:
BULKY SWEATERS WILL NEED TO BE REMOVED IN SOME CASES."

RENEWAL: UCRIHS approval is valid for one calendar year, beginning with
the approval date shown above. Investigators planning to
continue a progect beKond one year must use the green renewal
form (enclosed with t e original agproval letter or when a
project is renewed) to seek u date certification. There is a
maXimum of four.such expedite renewals osaible. Investigators
wishin to continue a progect beyond tha time need to submit it
again or complete reView.

REVISIONS: UCRIHS must review any changes in procedures involving human
subjects, rior to initiation of t e change. If this is done at
the_time o renewal, please use the green renewa1.form. To
reVise an approved protocol at any other time during the year,
send your written request to the. CRIHS Chair, requesting reVised
approval and referenCing the progect's IRB # and title. Include
in our request a description of the change and any revised
ins ruments, consent forms or advertisements that are applicable.

pnosnnus/ .

cannons: , Should.either of the followin arise during the course of the
work, investigators must noti UCRIHS promptly: (1) roblems
(unexpected side effects, comp aints, etc.) involving uman
subjects.or (2).changes in the research environment or new
information indicating greater risk to the human sub‘ects than
eXisted when the protocol was preViously reviewed an approved.

If we can be of any future help, lease do not hesitate to contact us
at (517)355-2180 or FAX (51714 2- 171.

  
  
 
  

' E. Wright, Ph D.
U IHS Chair

190

 

OFFICE OF
RESEARCH
AND
GRADUATE
STUDIES

niverslty Committee on
Research Involving
Human Subjects
(UCRIHS)

Michigan State University
:46 Administration Building
East Lansing. Michigan
48824—1046

517/355-2180
FAX: 517/353-2976

the Michigan State University
IDEA IS institutional Diversity:
Excellence in Action

MS J is an attirmatrve- action

an. .AI n—--1..-'.1.._‘1.‘

MICHIGAN STATE

 

UNIVERSITY

March 1, 1999

T0! Dr. Robert Malina
213 IM Sports Circle
Dept of Kinesiology
MSU

RE: IRB # 98118 CATEGORY: FULL REVIEW
RENEWAL APPROVAL DATE: March 1, 1999

TITLE: SECULAR CHANGE IN SIZE AND PHYSICAL FITNESS IN THE VALLEY OF
OAXACA, MEXICO

The University Committee on Research Involving Human Subjects' (UCRIHS) review of this
project is complete and I am pleased to advise that the rights and welfare of the human subjects

appear to be adequately protected and methods to obtain informed consent are appropriate.
Therefore, the UCRIHS APPROVED THIS PROJECTS RENEWAL.

This letter also acknowledges and approves the title change.

RENEWALS: UCRIHS approval is valid for one calendar year, beginning with the approval
date shown above. Projects continuing beyond one year must be renewed with the green
renewal form. A maximum of four such expedited renewals possible. Investigators wishing to
continUe a project beyond that time need to submit it again for a complete review.

REVISIONS: UCRIHS must review any changes in procedures involving human subjects,

prior to initiation of the change. If this is done at the time of renewal, please use the green
renewal form. To revise an approved protocol at any other time during the year, send your
written request to the UCRIHS Chair, requesting revised approval and referencing the project's
IRB# and title. Include in your request a description of the change and any revised instruments.
consent forms or advertisements that are applicable.

PROBLEMS/CHANGES: Should either of the following arise during the course of the work,
notify UCRIHS promptly: 1) problems (unexpected side effects, complaints, etc.) involving
human subjects or 2) changes in the research environment or new information indicating greater
risk to the human subjects than existed when the protocol was previously reviewed and
approved.

If we can be of further assistance, please contact us at 517 355-2180 or via email:

UCRIHS@piIot. msu. edu. Please note that all UCRII-IS forms are located on the web:
http: //www. msu. edu/unit/vprgs/UCRIHS/

Sincerely,

{av/5* al.,/a

aniel Br stein, S. J. D.
Vice UCRIHS Chair

191
DAB: bd

 

OFFICE OF
RESEARCH
AND
GRADUATE
STUDIES

University Committee on
Research Involving
Iloman Subjects

Michigan State Universi
246 Administration Buildi

East Lansing. Michigan“‘~..

48824-1 046

517/355-2180

FAX: 517/353-2976

3b: mmmsuedu/user/ucrihs
E-Mail: ucrihs@msu.edu

The Michigan sate University
IDEA is institutional Diversity
Excellence in Action.

MSU is an alﬁnnative—action.

   
 

MICHIGAN STATE

UNIVERSITY

 

March 14, 2000

TO: Robert MALINA
213 IM Sports Circle

RE“ IRB# 98-118 CATEGORY: FULL REVIEW

RENEWAL APPROVAL DATE: March 13, 2000

SECULAR CHANGE IN SIZE, STRENGTH AND MOTOR FITNESS IN THE
VALLEY OF OAXACA, MEXICO

TITLE:

The University Committee on Research Involving Human Subjects' (UCRIHS) review of this
project is complete and I am pleased to advise that the rights and welfare of the human subjects
appear to be adequately protected and methods to obtain informed consent are appropriate.
Therefore, the UCRIHS APPROVED THIS PROJECT'S RENEWAL.

This letter also approves the revised consent form and the addition of a

RENEWALS: UCRIHS approval is valid for one calendar year, beginning with the approval date
shown above. Projects continuing beyond one year must be renewed with the green renewal
form. A maximum of four such expedited renewal are possible. Investigators wishing to
continue a project beyond that time need to submit it again for complete review.

REVISIONS: UCRIHS must review any changes in procedures involving human subjects, prior
to initiation of the change. If this is done at the time of renewal, please use the green renewal
form. To revise an approved protocol at any other time during the year, send your written
request to the UCRIHS Chair, requesting revised approval and referencing the project's IRBlt
and title. Include in your request a description of the change and any revised instruments,
consent forms or advertisements that are applicable.

PROBLEMS/CHANGES: Should either of the following arise during the course of the work,
notify UCRIHS promptly: 1) problems (unexpected side effects, complaints, etc.) involving
human subjects or 2) changes in the research environment or new information indicating greater
risk to the human subjects than existed when the protocol was previously reviewed and
approved.

If we can be of further assistance, please contact us at 517 355-2180 or via email:
UCRIHS@piIot.msu.edu.

Sincerely,

DEW: bd

cc: Maria Eugenia Pena Reyes
213 IM Sports Circle 192

 

OFFICE OF
RESEARCH
AND
GRADUATE
STUDIES

Assistant Vice President
for Research

Michigan State University
245 Administration Building
East Lansing, Michigan
48824-1046

51 7/355-2180
FAX: 517/353-2976

MSU is an atﬁnnatiw-action,
equal -opportunity institution.

   
  

MICHIGAN STATE
U N I V E R S I T Y
May8,2001

 

TO: Robert MALINA
128 IM Sports Circle

RE: IRB # 98-118 CATEGORY: FULL REVIEW
RENEWAL APPROVAL DATE: May 8, 2001

TITLE: SECULAR CHANGE IN SIZE, STRENGTH AND MOTOR FITNESS IN THE VALLEY OF
OAXACA, MEXICO

The University Committee on Research Involving Human Subjects' (UCRIHS) review of this project
is complete and I am pleased to advise that the rights and welfare of the human subjects appear to
be adequately protected and methods to obtain informed consent are appropriate. Therefore, the
UCRIHS APPROVED THIS PROJECT'S RENEWAL.

This letter also approves the recategorization to Expedited 2-H (Continuing
analysis), archival research

RENEWALS: UCRIHS approval is valid for one calendar year, beginning with the approval date
shown above. Projects continuing beyond one year must be renewed with the green renewal form.
A maximum of four such expedited renewal are possible. Investigators wishing to continue a project
beyond that time need to submit it again for complete review.

REVISIONS: UCRIHS must review any changes in procedures involving human subjects, prior to
initiation of the change. If this is done at the time of renewal, please use the green renewal form. To
revise an approved protocol at any other time during the year, send your written request to the
UCRIHS Chair, requesting revised approval and referencing the project's IRB# and title. Include in
your request a description of the change and any revised instruments, consent forms or
advertisements that are applicable.

PROBLEMS/CHANGES: Should either of the following arise during the course of the work, notify
UCRIHS promptly: 1) problems (unexpected side effects, complaints, etc.) involving human subjects
or 2) changes in the research environment or new information indicating greater risk to the human
subjects than existed when the protocol was previously reviewed and approved.

If we can be of further assistance, please contact us at 517 355-2180 or via email:
UCRIHS@piIot.msu.edu.

Sincerely,

shir Kumar, M.D.
Interim Chair, UCRIHS

AK: bd

cc: Maria Eugenia Perla Reyes
128 IM Sports Circle

193

APPENDIX 11

DATA COLLECTION FORMS

I94

Anthropometry

Name

Birth date and place
Address
Menarche: Yes

1.

2

Type of clothing

Date of measurement

. Height

. Sitting height

. Bicondylar breadth

. Arm circ, relaxed

. Arm circ, ﬂexed

Age

 

 

Sex Number

 

School grade

 

 

Age

Menarche: N o

 

 

 

Weight kg

 

 

. Biacromial breadth

 

. Bicristal breadth

 

 

. Biepicondylar breadth

 

 

IO. Calf circumference

 

11. Triceps skinfold

 

12. Subscapular skinfold

 

i3. Suprailiac skinfold

 

14. Medial calf skinfold

 

15. Head length ‘

16. Head breadth

 

i7. Bizygomatic breadth

18. Bigonial breadth

 

 

Technician:

 

Observations:

Recorder:

 

 

I95

Physical Fitness

Name Age Sex Number

 

Birth date and place School grade

 

 

Grip strength, Right

 

Grip strength, Left

 

3 5-yard dash

 

Standing long jump

 

Sit and reach

 

Sit-ups

 

8 minute run walk (grades I through 3)

12 minute run walk (grades 4 through 6)

 

 

 

 

 

Place: Date:
Technician: Recorder:
Observations:

 

196

Demographic information

 

 

Name Age Sex Number
Birth date and place School grade
Address

 

How long have you been living in the community?

 

hrent information: Father Mother

Occupation

 

 

Age

 

 

Education

 

 

Place of birth

 

 

Family members:

 

Number of members

 

Adults Brothers Sisters

Number of rooms in your house

 

Household appliances:

 

 

 

Radio Yes No
TV—black & white Yes No
TV-color Yes No
Telephone Yes No
Refrigerator Yes No
Others?

Date Signature of Parent

Technican Observations

 

 

197

Activity Questionnaire (Grades 4 through 6)

 

 

 

Name Age Sex Number
Date _ Grade
Interviewer

 

1. At what time do you wake up?

 

2. Do you have breakfast before going to school ? Yes No

3. At what time do you leave for school?

 

4. What activities do you do at home before school?

 

 

. Do you have to do house chores before leaving for school? Yes No
. What do you do?

. At what time do you get at school?

 

 

. At what time do you ﬁnish classes?

 

OOONOSU'I

. What are your activities when you are in the classroom?

 

 

10. Do you have a physical education class? Yes No

l 1. How many days a week you have a PE class?

 

12. How much time of physical education per day?

 

13. At what time you get the school break?

 

I4. How do you spend the break time (sitting, standing, chaﬁng, eating, running,

playing)?

 

 

15. At what time do you return home after school?

l6. At what time you have lunch?

 

17. What do you do aﬁer school and before lunch?

 

 

18. What do you do aﬁer lunch?
19. Do you do household chores Yes No

 

198

20. What are your chores?

 

 

21. Do you do homework? Yes No
22. How long it takes to do your homework?
23. Do you have TV? Yes No

 

24. How many hours you watch TV each day?

 

25. Do you have a night meal (dinner)?Yes No
26. What do you do in your spare time[aller you are done with chores, homework] before

going to bed?

 

 

27. At what time do you go to bed?

 

28. Do you do sports? Yes No
29. What sports? (football basketball, other)

 

 

30. When and how long do you do sports (other places aﬁer school)?

 

31. What do you do when you are with your:

Father
Mother

Grandparents

 

 

 

Aunts/uncles

 

Brothers

 

Sisters
Boy friends
Girls friends

 

 

 

32. What do you do on Saturdays?

 

 

33. What do you do on Sundays?

 

199

(weekend activities: household chores, working activities with parents, brothers, sisters
games. go out oftown).

34. What do you like to do or to play the most?

 

 

35. What are the games played by children your age?

 

 

36. What are the games played by children older than you?

 

 

37. What are the games played by children younger than you?

 

 

200

APPENDIX III

TABLES OF DESCRIPTIVE STATISTICS

201

Table III.1. Descriptive statistics (means and standard deviations) for weight, height

and the body mass index (BMI) by age group in rural and urban children.

 

 

 

 

MALES:
Weight, kg Height, cm BMI, kg/m2

Age Rural Urban Rural Urban Rural Urban
GroupMean SD Mean SD Mean SD Mean SD Mean SD Mean SD

6 20.8 3.9 21.2 3.2 112.9 6.6 113.5 3.2 16.2 1.7 16.4 2.1

7 22.5 4.2 22.9 3.1 117.3 5.2 118.9 4.9 16.3 2.0 16.2 1.6

8 24.0 3.2 25.6 3.4 120.7 5.2 123.8 4.3 16.4 1.2 16.7 1.6

9 26.4 4.0 28.0 4.9 126.2 5.6 128.9 5.0 16.5 1.6 16.8 2.0
10 29.1 4.8 35.9 9.2 130.4 5.1 135.3 6.3 17.0 1.8 19.4 3.4
11 31.9 6.3 34.0 5.5 135.8 6.5 137.7 6.7 17.1 2.0 17.9 1.7
12 33.6 6.2 38.3 6.5* 142.0 6.3 144.9 10.2 16.5 2.2 18.8 2.7*
13 36.7 5.5 35.0 - 142.4 6.5 142.0 - 18.0 1.4' 17.4 -
FEMALES:

Weight, kg Height, cm BMI, kg/m2

Age Rural Urban Rural Urban Rural Urban
GroupMean SD Mean SD Mean SD Mean SD Mean SD Mean SD

6 19.3 2.1 21.0 2.3 111.5 4.7 113.5 4.1 15.5 1.1 16.3 1.5

7 20.2 2.4 23.4 4.0 115.2 4.7 119.6 6.6 15.2 1.1 16.3 1.8

8 24.5 4.8 27.0 4.3 122.0 6.4 125.9 6.4 16.3 2.0 17.0 1.8

9 27.6 5.2 29.6 5.6 126.6 5.0 129.7 5.9 17.1 2.5 17.5 2.3
10 29.4 5.6 30.4 5.4 130.1 6.9 133.2 7.5 17.3 2.3 17.1 2.3
11 34.2 6.2 37.2 8.8 137.3 6.1 141.4 7.1 18.1 2.1 18.4 3.1
12 42.1 8.8 41.9 7.5* 145.3 5.9 146.3 5.4 19.8 2.7 19.8 2.5*
13 38.4 5.4 45.2 - 144.5 6.8 153.8 - 18.3 1.5 19.1 -

 

weight and BMI are not included in the descriptive statistics.

*One male and one female in the respective age groups were obese; their

202

Table 111.2. Descriptive statistics (means and standard deviations) for sitting height,

estimated leg length and the sitting height/height ratio (SH/H Ratio) by age group in

rural and urban children.

 

 

 

 

MALES:
Sitting Height, cm Leg Length, cm SH/H Ratio, %
Age Rural Urban Rural Urban Rural Urban
GroupMean SD Mean SD Mean SD Mean SD Mean SD Mean SD
6 62.4 3.6 62.9 2.4 50.5 3.4 50.6 1.9 55.3 1.1 55.4 1.2
7 64.5 2.9 65.5 2.5 52.8 2.8 53.4 3.2 55.0 1.0 55.1 1.4
8 66.0 3.0 67.6 2.1 54.7 3.1 56.2 2.9 54.7 1.4 54.6 1.2
9 68.3 3.1 69.6 2.7 57.8 3.3 59.3 3.4 54.2 1.2 54.0 1.5
10 70.0 2.3 72.3 3.4 60.4 3.2 63.0 3.5 53.7 1.0 53.4 1.0
11 71.2 2.8 73.0 3.1 64.6 4.6 64.6 4.3 52.4 1.6 53.1 1.2
12 75.0 3.0 76.7 4.7 67.0 3.9 68.3 5.8 52.8 1.2 52.9 1.0
13 75.3 3.7 74.2 - 67.1 3.6 67.8 - 52.9 1.1 52.2 -
FEMALES:
Sitting Height, cm Leg Length, cm SH/H Ratio, %
Age Rural Urban Rural Urban Rural Urban
GroupMean SD Mean SD Mean SD Mean SD Mean SD Mean SD
6 61.8 2.6 62.8 2.6 49.7 2.8 50.8 2.1 55.5 1.3 55.3 1.0
7 62.9 2.6 65.2 3.5 52.3 3.8 54.4 3.8 54.6 2.1 54.5 1.4
8 66.3 2.9 67.8 3.6 55.8 3.8 58.0 3.6 54.3 1.2 53.9 1.3
9 68.2 2.1 69.8 3.4 58.4 3.4 59.9 3.3 53.9 1.2 53.8 1.2
10 69.5 3.3 70.9 4.3 60.6 4.0 62.3 4.2 53.5 1.0 53.3 1.5
11 73.6 3.0 74.9 4.5 63.7 3.7 66.5 3.7 53.6 1.0 53.0 1.4
12 75.6 6.7 77.5 2.3 69.8 1.9 68.8 4.4 51.9 2.7 53.0 1.6
13 77.5 3.9 82.1 - 67.0 3.4 71.7 - 53.7 0.9 53.4 -

 

203

Table 111.3. Descriptive statistics (means and standard deviations) for skeletal

breadths by age group in rural and urban children: MALES.

 

Biacromial, cm

Bicristal, cm

 

Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 26.0 2.1 26.5 1.1 18.9 1.2 19.0 1.0
7 26.8 1.8 27.6 1.2 19.3 1.4 20.0 1.1
8 27.6 1.6 28.6 1.3 19.7 1.1 20.4 0.8
9 28.9 1.3 29.6 1.6 20.5 1.3 21.4 1.2
10 29.7 1.4 31.5 1.9 21.1 1.3 23.1 2.0
11 30.5 2.0 31.4 1.8 21.8 1.4 22.8 1.5
12 32.3 1.6 33.7 3.3 22.2 1.6 24.9 3.8
13 32.5 1.3 32.8 - 22.5 1.0 22.9 -

 

Bicondylar, cm

Biepicondylar, cm

 

Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 7.2 0.5 7.4 0.5 4.6 0.3 4.7 0.4
7 7.4 0.5 7.6 0.3 4.7 0.4 4.7 0.3
8 7.7 0.4 7.8 0.4 4.8 0.3 4.8 0.3
9 7.9 0.5 8.0 0.4 5.0 0.4 5.0 0.3
10 8.1 0.4 8.5 0.6 5.2 0.4 5.5 0.5
11 8.3 0.5 8.5 0.4 5.3 0.4 5.4 0.4
12 8.6 0.5 9.0 0.9 5.4 0.4 5.8 0.7
13 8.7 0.5 8.8 - 5.7 0.3 5.6 -

 

204

Table 111.4. Descriptive statistics (means and standard deviations) for skeletal

breadths by age group in rural and urban children: FEMALES.

 

Biacromial, cm

Bicristal, cm

 

Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 25.5 0.9 26.4 1.0 18.3 1.1 19.2 0.9
7 26.1 1.2 27.4 1.5 18.5 0.9 19.8 1.3
8 27.7 1.8 28.7 1.6 20.1 1.4 21.2 1.5
9 29.1 1.6 29.9 1.4 21.0 1.4 22.0 1.5
10 29.6 1.8 30.3 2.2 21.2 1.4 22.1 1.5
11 31.5 1.4 32.2 2.9 22.4 1.4 23.5 1.6
12 33.5 1.4 34.3 2.7 24.9 1.4 25.5 2.3
13 32.7 2.1 34.0 - 23.5 1.8 26.3 -

 

Bicondylar, cm

Biepicondylar, cm

 

Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 6.9 0.4 7.1 0.3 4.4 0.2 4.6 0.2
7 6.9 0.3 7.2 0.4 4.5 0.2 4.6 0.3
8 7.4 0.5 7.6 0.4 4.8 0.3 4.8 0.3
9 7.7 0.5 7.9 0.5 4.9 0.3 5.0 0.4
10 7.9 0.5 7.9 0.5 5.0 0.4 5.1 0.4
11 8.2 0.4 8.3 0.5 5.2 0.3 5.3 0.4
12 8.4 0.4 8.6 0.6 5.7 0.1 5.6 0.5
13 8.4 0.5 8.3 - 5.6 0.3 5.5 -

 

205

Table 111.5. Descriptive statistics (means and standard deviations) for limb

circumferences by age group in rural and urban children: MALES.

 

Arm Circumference, cm

Calf Circumference, cm

 

 

 

Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 16.9 1.4 17.2 1.8 22.6 1.6 23.2 1.7
7 17.2 1.8 17.4 1.4 23.1 1.9 23.7 1.3
8 17.7 1.3 18.0 1.7 24.2 1.5 24.5 1.6
9 18.3 1.8 18.5 1.8 24.9 1.8 25.6 1.7
10 18.7 1.5 21.2 2.9 25.7 1.9 28.2 2.8
11 19.6 2.2 20.1 1.7 26.7 2.3 27.6 2.0
12 19.7 2.3 22.4 4.8 27.2 2.1 29.8 5.0

13 20.4 1.6 20.1 - 28.3 1.7 28.1 -

Estimated Arm Estimated Calf

Muscle Circumference, cm Muscle Circumference, cm

Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 14.5 1.1 14.8 1.5 20.2 1.2 20.6 1.5
7 14.8 1.3 15.1 1.3 20.7 1.5 21.3 1.2
8 15.4 1.0 15.5 1.4 21.8 1.1 21.9 1.3
9 15.9 1.3 16.0 1.7 22.3 1.6 23.0 1.6
10 16.1 1.5 18.2 2.4 23.1 1.7 25.1 2.2
11 17.0 1.7 17.1 1.7 24.1 1.9 24.7 1.9
12 17.7 1.7 19.5 3.9 25.0 1.9 26.4 4.1

13 18.2 1.2 18.5 - 25.6 1.3 25.4 -

 

206

Table 111.6. Descriptive statistics (means and standard deviations) for limb

circumferences by age group in rural and urban children: FEMALES.

 

Arm Circumference, cm

Calf Circumference, cm

 

 

 

Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 16.5 1.1 17.4 1.1 22.3 1.3 23.3 1.2
7 16.6 1.1 17.7 1.5 22.5 1.2 23.7 1.9
8 18.3 2.0 18.6 1.8 24.1 2.1 25.2 1.8
9 19.0 2.1 19.1 2.0 24.8 3.4 26.0 2.1
10 19.3 2.2 19.4 1.7 26.0 2.4 26.3 2.1
11 20.6 1.7 21.1 2.4 27.3 2.2 28.3 2.4
12 21.9 1.6 23.2 3.0 29.9 1.4 30.2 2.9

13 20.9 1.8 21.9 - 28.1 1.4 30.5 -

Estimated Arm Estimated Calf

Muscle Circumference, cm Muscle Circumference, cm

Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 13.9 0.8 14.6 1.0 19.7 1.1 20.6 1.0
7 14.0 1.0 15.0 1.4 20.0 1.0 20.9 1.6
8 15.5 1.6 15.9 1.6 21.2 1.7 22.4 1.6
9 16.1 1.6 16.3 1.9 21.8 2.9 23.0 1.7
10 16.3 1.9 16.6 1.6 22.6 2.0 23.3 1.7
11 17.5 1.6 18.2 2.0 23.9 1.9 25.0 2.0
12 18.4 1.8 19.6 2.5 26.2 1.3 26.3 2.3

13 17.7 1.8 18.9 - 24.9 1.6 27.2 -

 

207

Table 111.7. Descriptive statistics (means, standard deviations and medians) for

skinfold thicknesses by age group in rural and urban children: MALES.

 

Triceps Skinfold, mm Subscapular Skinfold, mm
Age Rural Urban Rural Urban
GroupMean SD MD Mean SD MD Mean SD MD Mean SD MD

 

7.8 1.8 7.0 7.8 1.6 7.0 6.0 2.2 6.0 6.1 2.3 6.0
7.5 2.0 7.0 7.4 1.3 8.0 6.7 2.3 6.0 5.9 1.7 6.0
7.5 1.9 7.0 8.0 1.7 8.0 6.3 2.0 6.0 6.8 2.4 6.0
7.6 2.2 8.0 7.9 1.6 8.0 6.7 2.3 6.0 7.0 2.1 7.0
10 8.0 2.4 7.0 9.6 2.1 9.0 7.1 2.8 6.0 9.6 3.7 8.0
11 8.3 2.1 8.0 9.3 2.6 9.0 7.5 2.7 6.0 8.1 2.1 8.0
12 6.2 2.6 5.0 9.3 3.4 8.0 7.3 3.0 7.0 10.6 6.9 9.0

\OOO\IO\

 

13 7.1 1.6 7.0 5.0 - - 7.9 2.8 7.0 6.5 - -
Suprailiac Skinfold, mm Medial Calf Skinfold, mm -
Age Rural Urban Rural Urban

GroupMean SD MD Mean SD MD Mean SD MD Mean SD MD

 

7.7 2.8 7.0 8.4 2.5 8.0 7.6 2.2 7.0 8.3 1.5 8.0
8.2 3.1 7.0 8.2 2.1 8.0 7.9 2.5 8.0 7.6 1.8 8.0
8.3 2.8 8.0 9.3 3.1 9.0 7.6 1.9 7.0 8.3 1.9 8.0
8.9 3.3 8.0 9.5 2.3 9.0 8.0 1.9 8.0 8.2 1.6 8.0
10 8.9 3.2 8.0 12.4 3.9 12.0 8.2 2.3 8.0 9.7 2.7 9.0
11 8.7 4.0 8.0 11.1 3.0 11.0 8.3 1.9 8.0 9.2 1.9 8.0
12 8.3 3.8 7.0 13.2 6.6 12.0 7.1 2.0 8.0 10.7 4.4 10.0
13 8.6 2.8 8.0 6.5 - - 8.4 2.7 8.0 8.5 - -

\OOO\IO\

 

208

Table 111.8. Descriptive statistics (means, standard deviations and medians) for

skinfold thicknesses by age group in rural and urban children: FEMALES.

 

Triceps Skinfold, mm Subscapular Skinfold, mm
Age Rural Urban Rural Urban
GroupMean SD MD Mean SD MD Mean SD MD Mean SD MD

 

8.3 2.1 8.0 8.7 1.5 8.0 6.9 2.4 7.0 7.1 2.1 7.0
8.3 1.9 8.0 8.4 1.5 8.0 6.3 1.7 6.0 7.5 2.6 7.0
9.1 2.3 8.0 8.5 1.4 8.0 8.2 3.4 8.0 8.0 2.2 8.0
9.0 2.3 8.0 8.8 1.8 8.0 8.7 3.6 8.0 9.0 2.8 8.0
10 9.7 2.4 9.0 8.9 1.5 9.0 9.6 4.1 8.0 8.3 2.4 9.0
11 10.0 2.2 10.0 9.1 1.7 9.0 10.2 2.6 10.0 9.8 2.8 10.0
12 11.0 1.4 12.0 11.3 2.8 12.0 12.5 3.9 14.0 12.1 4.3 12.0

\OOO\IC\

 

13 10.3 2.1 11.0 9.5 ' - - 10.6 1.7 11.0 11.5 - -
Suprailiac Skinfold, mm Medial Calf Skinfold, mm
Age Rural Urban Rural Urban

GroupMean SD MD Mean SD MD Mean SD MD Mean SD MD

 

7.8 2.6 7.0 8.5 1.8 8.0 8.3 1.9 8.0 8.5 1.4 8.0

8.4 3.0 8.0 9.4 2.7 9.0 8.2 1.6 8.0 8.7 1.5 8.0
10.2 2.8 10.0 9.9 2.7 10.0 9.4 2.5 9.0 9.0 2.3 9.0
10.7 3.9 11.0 10.5 3.2 9.0 9.7 3.3 8.0 9.8 2.3 9.0
10 11.4 4.0 10.0 10.5 2.5 10.0 10.7 3.1 11.0 9.6 2.0 9.0
11 12.7 2.7 13.0 12.0 2.8 11.0 11.0 2.3 11.0 10.6 2.1 11.0
12 13.0 1.4 14.0 14.3 3.8 13.0 11.7 1.3 12.0 12.4 3.9 12.0
13 12.8 1.5 13.0 15.0 - - 10.0 1.0 10.0 10.5 - -

\OOO\IO\

 

209

Table 111.9. Descriptive statistics (means, standard deviations and medians) for the

sum of four skinfold thicknesses (triceps, subscapular, suprailiac, medial calf) and

the trunk-extremity ratio (TER, subscapular + suprailiac/triceps + medial call) by age

group in rural and urban children.

 

 

 

 

MALES

Sum of Skinfolds, mm TER
Age Rural UrbanRural Urban
GroupMean SD MD Mean SD MD Mean SD MD Mean SD MD
6 29.0 8.3 27.0 30.5 6.6 28.5 0.87 0.15 0.87 0.90 0.23 0.90
7 30.3 8.8 27.0 29.1 5.7 29.0 0.97 0.20 0.92 0.94 0.15 1.00
8 29.7 7.8 28.5 32.5 8.0 31.0 0.96 0.16 0.92 0.98 0.221.00
9 31.2 8.5 29.0 32.5 6.1 32.0 1.00 0.22 1.00 1.03 0.21 1.06
10 32.2 9.2 29.5 41.3 11.4 38.0 0.99 0.25 0.93 1.13 0.22 1.11
11 32.8 9.7 30.0 37.9 7.0 37.0 0.95 0.24 1.00 1.05 0.21 1.06
12 29.0 9.9 25.0 43.8 20.5 37.5 1.16 0.26 1.10 1.17 0.25 1.10
13 31.9 8.6 30.5 26.5 - - 1.07 0.20 1.08 0.97 - -
FEMALES

Sum of Skinfolds, mm TER
Age Rural UrbanRural Urban
GroupMean SD MD Mean SD MD Mean SD MD Mean SD MD
6 31.3 7.8 30.0 32.8 5.6 32.0 0.88 0.17 0.83 0.90 0.16 0.87
7 31.2 6.4 30.0 34.1 6.8 34.0 0.89 0.20 0.89 0.98 0.23 0.95
8 36.8 9.9 34.5 35.3 7.7 34.0 1.00 0.19 1.00 1.01 0.161.06
9 38.0 12.3 32.5 38.1 8.7 35.0 1.03 0.21 1.02 1.05 0.20 1.04
10 41.5 11.7 38.0 37.4 6.6 36.0 1.02 0.21 1.00 1.02 0.23 0.95
11 43.9 8.1 43.0 41.4 8.1 42.0 1.10 0.19 1.11 1.10 0.18 1.07
12 48.3 5.9 50.0 50.1 13.9 49.0 1.12 0.21 1.17 1.12 0.16 1.16
13 43.8 5.3 43.5 46.5 - - 1.14 0.08 1.13 1.30 - -

 

210

Table 111.10. Descriptive statistics (means and standard deviations) for muscular

strength by age group in rural and urban children: MALES

 

 

 

 

Right Grip, kg Left Grip, kg
Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 9.5 1.8 9.6 1.9 8.7 1.9 9.1 1.9
7 10.9 1.7 11.2 2.3 10.3 2.2 10.7 2.3
8 12.0 2.6 12.3 2.8 11.2 2.7 12.2 2.5
9 14.9 2.6 14.3 2.7 14.0 2.9 13.6 2.4
10 16.3 3.0 17.9 4.1 15.2 2.9 17.0 4.4
11 18.3 3.6 18.1 3.4 17.0 4.0 17.4 3.9
12 21.4 2.8 22.0 7.0 19.3 2.9 20.3 5.9
13 22.6 3.4 20.5 - 20.6 3.5 22.0 -
Sum Right + Left Grip, kg Sum Grip/Weight, kg/kg
Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 18.2 3.6 18.8 3.6 0.89 0.14 0.89 0.17
7 21.2 3.7 21.8 4.4 0.95 0.13 0.96 0.19
8 23.2 5.1 24.5 5.1 0.97 0.17 0.96 0.18
9 28.9 5.2 27.9 4.9 1.10 0.17 1.01 0.15
10 31.5 5.7 34.9 8.1 1.09 0.16 0.99 0.15
11 35.3 7.5 35.5 7.2 1.11 0.12 1.05 0.15
12 40.8 5.2 42.3 12.8 1.24 0.17 0.99 0.15
13 43.2 6.7 42.5 - 1.18 0.10 1.21 -

 

Sum Grip/Weight is the sum of right and left grip strength divided by body weight.

211

Table III. 1 1. Descriptive statistics (means and standard deviations) for muscular

strength by age group in rural and urban children: FEMALES

 

 

 

 

Right Grip, kg Left Grip, kg
Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 8.8 1.4 8.5 1.5 7.7 1.4 7.8 1.6
7 9.3 2.2 10.2 2.0 8.6 1.9 9.6 2.1
8 11.6 2.3 12.3 2.6 10.7 2.5 11.6 2.9
9 14.2 2.7 13.5 2.5 13.1 2.5 12.5 1.9
10 15.3 2.9 15.2 3.3 13.6 2.9 14.0 3.2
11 18.0 2.7 17.9 4.3 16.3 3.3 17.1 3.5
12 21.0 3.6 19.9 4.3 20.3 2.6 19.9 3.4
13 21.6 3.4 26.0 - 19.8 3.6 23.5 -
Sum Right + Left Grip, kg . Sum Grip/Weight, kg/kg
Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 16.5 2.5 16.3 2.7 0.86 0.12 0.77 0.11
7 17.9 4.0 19.8 3.9 0.89 0.17 0.85 0.14
8 22.2 4.5 23.9 5.3 0.91 0.14 0.88 0.13
9 27.4 5.1 26.0 4.2 1.00 0.16 0.89 0.15
10 28.9 5.6 29.2 6.3 1.00 0.16 0.97 0.17
11 34.3 5.8 35.0 7.6 1.01 0.11 0.96 0.17
12 41.3 5.3 39.7 7.4 0.99 0.07 0.90 0.22
13 41.4 6.8 49.5 - 1.08 0.14 1.12 -

 

Sum Grip/Weight is the sum of right and left grip strength divided by body weight.

212

Table 111.12. Descriptive statistics (means and standard deviations, medians for sit-

ups) for indicators of physical ﬁtness by age group in rural and urban children:

 

 

 

 

MALES
Sit and Reach, cm Sit-Ups, n/30 sec

Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD MD Mean SD MD
6 26.5 4.5 27.9 3.8 5.7 4.3 7.0 8.4 4.8 9.0
7 26.8 3.6 28.4 4.0 8.4 3.4 9.0 10.9 4.0 12.0
8 26.4 4.1 27.9 3.8 7.2 4.4 8.0 12.6 5.0 13.0
9 25.7 4.9 27.9 4.5 9.3 3.9 10.0 13.2 4.8 14.0
10 28.1 5.3 26.4 5.2 11.9 4.3 12.0 13.4 4.7 14.0
11 26.0 4.5 27.6 4.8 12.4 3.9 13.0 14.5 3.1 14.0
12 25.1 5.8 26.8 6.6 11.2 1.5 11.0 14.4 5.7 15.0
13 27.0 4.1 30.8 - 13.4 2.2 13.0 17.0 -

Standing Long Jump, cm 35 Yard (32.3 m) Dash, sec
Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 77.3 14.2 93.4 19.2 7.81 0.55 7.97 0.54
7 89.8 17.7 98.3 18.6 7.43 0.41 7.62 0.55
8 91.5 20.9 110.0 15.8 7.31 0.67 7.22 0.47
9 103.0 19.4 122.1 16.7 6.80 0.49 7.10 0.58
10 107.9 21.6 130.3 14.6 6.75 0.45 6.59 0.54
11 119.5 10.6 123.9 18.9 6.72 0.31 6.53 0.56
12 109.0 32.5 135.9 23.0 6.45 0.38 6.25 0.48

13 116.1 20.1 159.1 - 6.43 0.26 5.79 -

 

213

Table 111.13. Descriptive statistics (means and standard deviations, medians for sit-

ups) for indicators of physical ﬁtness by age group in rural and urban children:

 

 

 

 

FEMALES
Sit and Reach, cm Sit-Ups, n/30 sec
Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD MD Mean SD MD
6 27.3 4.0 26.7 3.8 4.2 3.9 3.0 6.6 4.8 6.0
7 26.8 3.2 29.2 4.6 7.4 4.2 8.0 8.4 4.9 8.0
8 27.0 3.9 27.6 3.5 7.0 3.7 8.0 10.7 4.7 12.0
9 27.7 5.1 27.5 5.7 7.0 4.3 9.0 11.0 4.4 12.0
10 25.3 4.1 29.2 5.0 8.6 4.8 9.0 10.4 4.4 11.0
11 27.7 4.3 27.8 5.5 7.6 5.0 9.0 12.3 3.4 12.0
12 27.3 3.2 30.5 6.1 4.0 0.8 4.0 10.1 5.3 11.0
13 25.8 4.0 28.0 - 12.6 4.0 14.0 11.5 - -
Standing Long Jump, cm 35 Yard (32.3 m) Dash, sec
Age Rural Urban Rural Urban
Group Mean SD Mean SD Mean SD Mean SD
6 61.6 16.4 75.5 14.6 8.68 0.57 8.84 0.70
7 74.5 17.6 86.1 25.1 8.04 0.81 8.37 0.83
8 85.0 18.8 98.1 15.8 7.69 0.73 7.89 0.51
9 91.3 23.0 104.0 14.0 7.47 0.60 7.56 0.61
10 90.2 15.1 107.1 18.6 7.36 0.38 7.08 0.63
11 90.9 16.0 113.2 11.7 7.19 0.59 6.78 0.51
12 88.8 12.6 114.3 12.2 7.22 0.47 7.01 0.67

13 86.5 9.2 94.1 - 7.09 0.85 7.57 -

 

214

Table 111.14. Descriptive statistics (means, standard deviations, medians) for the

distance run (meters) by age group in rural and urban children.

 

 

 

 

MALES
Rural Urban
Grade Mean SD Median Mean SD Median
1* 1172 142 1170 1028 117 1020
2 1228 157 1230 1064 133 1086
3 1209 140 1230 1147 164 1109
4** 1767 213 1765 1742 272 1792
5 1840 222 1820 1805 219 1840
6 2104 226 2170 1908 303 1898
FEMALES
Rural Urban
Grade Mean SD Median Mean SD Median
1* 1095 .130 1090 985 88 974
2 1070 152 1070 1045 123 1071
3 1200 194 1159 1098 143 1116
4** 1618 234 1614 1668 231 1650
5 1556 205 1612 1573 227 1581
6 1742 193 1770 1810 204 1797

 

*For grades 1-3, it is the distance run in 8 minutes.
"For gtrades 4-6, it is the distance run in 12 minutes.

215

Bibliography

Agarwal KN. 1993. Inﬂuence of nutritional deprivation on intelligence. Cognition,
fine motor coordination, electrophysiological pattern, learning abilities and
study of possible mechanisms in animal models. In Gopalan C, ed: Recent
Trends in Nutrition. Delhi: Oxford University Press, p 208-220.

Agarwal KN, Agarwal DK, Kumar A,Upadyay SK. 1998. Sequelae of early
undemutrition on reaction time of rural children at 1-14 years. Indian J Med
Res 107:98-102.

Aguirre A, Camposortega S. 1980. Evaluacién de la informacion basica sobre
mortalidad infantil en Mexico. Demograﬁa y Economia 14:447-466.

Alba F. 1993. Crecimiento demografrco y transformacion econémica, 1930-1970. In:
CONAPO. El Poblamiento de México. Una Vision Historico Demograﬁca.
Tomo IV. México en el Siglo XX. Hacia el nuevo milenio: El poblamiento en
perspectiva. Mexico: Editorial Azabache, p 74-95.

Allen LH. 1990. Functional indicators and outcomes of undemutrition. J Nutr 120:
924-932.

Allen LH. 1993. The nutrition CRSP: What is marginal malnutrition, and doesn’t
affect human function? Nutr Rev 51: 225-267.

Amdurer LR. 1978. Nutrition in a Zapotec-speaking rural community, Oaxaca,
Mexico. Master’s Thesis, University of Texas at Austin.

American Alliance for Health, Physical Education, Recreation and Dance. 1980.
Health Related Physical Fitness Test Manual. Reston, VA: American Alliance
for Health, Physical Education, Recreation and Dance.

Arboleda-Ramirez C. 1999. Condiciones de salud de la poblacién migrante en el
entorno laboral. Situacion y perspectiva. Coloquio nacional sobre politicas
pI'Iblicas de atencién al migrante, Oaxaca de Juarez, 78 Mayo 1999 (ht_tp://

www.0axaca. gob.mx ).

Arechiga J, Serrano C. 1981 Parametros antropométricos de crecimiento en un grupo
indigena mayance (Tojolabales). Estudios de Antropologia Maya, (UNAM,
Centro de Estudios Mayas Mexico) 13:307-337.

Arellanes A. 1988. Del camarazo al cardenismo. In L Reina, J Sanchez-Cortez (eds):
Historia de la Cuestion Agraria Mexicana. Estado de Oaxaca, Volumen II,
1925-1986. Mexico, DF: Juan Pablos Editor, SA, p 77-97.

216

Avila-Curiel A, Shama-Levy T, Chavez-Villasa A. 1996. Encuesta Nacional de
Alimentacion en el Medio Rural. Mexico, DF: Instituto Nacional de la
Nutricion Salvador Zubiran.

Beneﬁce E. 1993. Physical activity, cardiorespiratory ﬁtness, motor performance,
and growth of Senegalese pre-adolescents. Am J Hum Biol 5:653-667.

Bielicki T. 1986. Physical growth as a measure of economic well-being of
populations: The twentieth century. In F Falkner and JM Tanner, eds: Human
Growth. A Comprehensive Treatise, Vol 3. New York: Plenum Press, p 283-305.

Bielicki T. 1999. Secular trends in growth: Human biologists’ contribution to the
understanding of social change. In FE Johnston, B Zemel, PB Eveleth, eds:
Human Growth in Context. London: Smith-Gordon, p 303-311.

Bielicki T, Hulanicka B. 1998. Secular trends in stature and age at menarche in
Poland. In E Bodzsar and C Susanne, eds: Secular Growth Changes in
Europe. Budapest: Eotvos University Press, p 263-279.

Bielicki T, Malina RM, Waliszko A. 1992. Monitoring the dynamics of social
stratiﬁcation: Statural variation among Polish conscripts in 1976 and 1986. Am
J Hum Biol 4:345-352.

Bielicki T, Szklarska A, Welon Z, Brajczewski C (1997) Nierownosci spoleczne w
Polsce: Antropologiczne badania poborowych w trzydziestoleciu 1965-1995.
Monographs of the Institute of Anthropology, No. 16. Wroclaw, Poland: Polish
Academy of Sciences.

Bielicki T, Waliszko A. 1991. Urbanization-dependent gradients in stature among
Polish conscripts in 1976 and 1986. Am J Hum Biol 32419-424.

Boas F. 1912. Changes in the bodily form of descendants of immigrants. Am Anthrop
14:530-563.

Boas F. 1922. Report on an anthropometric investigation of the population of the
United States. J AM Stat Assoc 18:181-209.

Bogin B. 1988. Rural-to-urban migration. In CGN Mascie-Taylor, GW Lasker, eds:
Biological Aspects of Migration. Cambridge: Cambridge University Press, p 90-129.

Bouchard C, Malina RM, Pérusse L. 1997. Genetics of Fitness and Physical
Performance. Champaign, IL: Human Kinetics.

Buchberger J. 1979. Leistungsphysiologische Charakteristik von Schweizer Berg-
und Stadtkindern im Pubertatsalter. Helvet Paediatr Acta 34:223-234.

217

Buschang PH. 1980. Growth status of school children 6 to 13 years of age in a rural
Zapotec-speaking community in the Valley of Oaxaca, Mexico. Doctoral
Dissertation, University of Texas at Austin.

Buschang PH, Malina RM. 1983. Growth, in height and weight of mild-to-
moderately undernourished Zapotec school children. Hum Biol 55:587-597.

Buschang PH, Malina RM, Little BB. 1986. Linear growth Zapotec schoolchildren:
Growth status and yearly velocity for leg length and sitting height. Ann Hum
Biol 13:225-234.

Butte NF, Villalpando S, Wong WE, F lores-Huerta S, Hernandez-Beltran MJ,
O’Brian-Smith E. 1993. Higher total energy expenditure contributes to growth
faltering in breastfed infants living in rural Mexico. J Nutr 123:1028-1035.

Buzina R, Bates C J, Vander Beek J, Chandra RK, Hallberg L, Keseker J, Mertz W,
Pietrzik K, Pollit E, Sandstead HH, Schaalch W. 1989. Workshop on functional
signiﬁcance of mild-to-moderate malnutrition. Am J Clin Nutr 50:172-176.

Cabrera-Acevedo G. 1993. México en el siglo XX, Introduccion. InzConapo
Poblamiento de Mexico. Una Vision Historico Demograﬁca. Tomo IV. México
en el Siglo XX. Hacia el nuevo milenio: El poblamiento en perspectiva.
México: Editorial Azabache, p 9-31.

Calloway DH. 1982. Functional consequences of malnutrition. Rev Infec Dis 4:736-
735.

Cameron N, Kgamphe J S, Leschner KF, Farrat PJ. 1992. Urban-rural differences in
the growth of South African black children. Ann Hum Biol 19: 23-33.

Canales JL, L0pez P, Narro J, Almada I. 1980. El subregistro de la natalidad y la

mortalidad en una comunidad rural en Mexico. Salud Publica de México
22: 123-134.

Centers for Disease Control and Prevention (2000) National Center for Health
Statistics CDC growth charts: United States. http://www.cdc.ggv/

growthchartshtm.

Chavez A, Martinez C. 1984. Behavioral measurements of activity in children and
their relation to food intake in a poor community. In E Pollitt, P Amante, eds:
Energy Intake and Activity. New York: Alan R Liss, p 303-321.

Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. 2000. Establishing a standard

deﬁnition for child overweight and obesity worldwide: International survey.
Brit Med J 320:1-6.

218

Consejo Nacional de Poblacion. 1998. Indices de Marginacion, 1995. Mexico, DF:
Consejo Nacional de Poblacion.

Consejo Nacional de Poblacion. 2000. Caudemos de Salud Reproductiva Oaxaca.
Mexico, DF: Consejo Nacional de Poblacion.

Cooper Institute for Aerobics Research. 1994. The Prudential Fitnessgram: Test
Administration Manual. Dallas, TX: Cooper Institute for Aerobics Research.

Cordero E. 1968. La subestimacion de la mortalidad infantil en México. Demograﬁa
y Economia 2:44-62.

Cravioto J. 1980. Severe malnutrition and development of motor skills in children.
Ann Nestle 44:22-42.

Cravioto J, Arrieta R. 1986. Nutrition, mental development, and learning. In F
Falkner, JM Tanner, eds: Human Growth. A Comprehensive Treatise, Vol 3.
New York: Plenum Press, p 501-536.

Crowley E. 1999. Rural poverty: Population dynamics, local institution and access to
resources. Sustainable development. Rome: Food and Agriculture Organization

(FAO) of the United Nations, www.FAO.org/sﬂwpdirect/wprc009 l =htm.

Cruickshank S, Purcell M. 1998. Mexico: More poor than 15 years ago. Grassroots,
Mexico. www.socwatch.org-uy/1228.

Cureton KJ. 1994. Aerobic capacity. In JR Morrow, HB Falls, HW Kohl, eds: The

Prudential Fitnessgram: Technical Reference Manual. Dallas, TX: Cooper
Institute for Aerobics Research, p 33-55.

Desai ID, Waddell C, Dutra S. 1984. Marginal Nutrition and reduced physical work
capacity of migrant adolescent boys in Southern Brazil. Am J Clin Nutr
40:135-145.

Dewey KG. 1985. Nutrition, social impact, and development: A Mexican case. In W
Derman, S Whiteford, eds: Social Impact Analysis and Development Planning
in the Third World. Boulder, CO: Westview Press, p 160-177.

Dilley B. 1993. Climate Change and Agricultural Transformation in the Oaxaca
Valley, Mexico. Thesis in Geography. Pennsylvania State University.

Direccion General de Estadistica e Informatica de la Secretaria de Salud, México.

2001. Principales resultados de la estadistica sobre mortalidad en Mexico,
1999. Salud Publica de Mexico 43:67-73.

219

Diskin M. 1991. Lack of access to land and food in El Salvador. In S Whiteford, A
Ferguson, eds: Harvest of Want: Hunger and Food Security in Central America
and Mexico. Boulder, CO: Westview Press, p 103-125.

Eastwood-Garcia S, Kaiser LL, Dewey K. 1990. Self-regulation of food intake
among rural Mexican preschool children. Eur J Clin Nutr 44:371-380.

Enge KI, Martinez-Enge P. 1991. Land malnutrition, and health: The dilemmas of
development in Guatemala. In S Whiteford, A Ferguson, eds: Harvest of Want:

Hunger and Food Security in Central America and Mexico. Boulder, CO:
Westview Press, p 103-125.

Espinosa MP, Sigman MD, Newman CG, Bwibo NO, McDonald MA. 1992.
Playground behaviors of school-age children in relation to nutrition, schooling
and family characteristics. Dev Psychol 28:1188-1195.

Eveleth PB, Tanner J M. 1976. Worldwide Variation in Human Growth. Cambridge:
Cambridge University Press.

Eveleth PB, Tanner JM. 1990. Worldwide Variation in Human Growth, 2"d edition.
Cambridge: Cambridge University Press.

FAQ (Food and Agriculture Organization). 1996. Twenty-fourth FAO regional
Conference for Latin America and the Caribbean. World food summit: State of
food security in Latin America and the Caribbean. Asuncion, Paraguay, 2 to 6

July, 1996 (http://www.fao.org).

Faulhaber J. 1989. Crecimiento: Somatometria de la Adolescencia. México:
Universidad Nacional Autonoma de México.

F aulhaber J, Villanueva M. 1976. Investigacion Longitudinal del Crecimiento.
México: Instituto Nacional de Antropologia e Historia, Coleccion
Cientifica, 26.

F erro-Luzzi A. 1985. Work capacity and productivity in long—term adaptation to low
energy intakes. In K Baxter, JC Waterlow, eds: Nutritional Adaptation in Man.

London: John Libbey, p 61-69.

Fleishman EA. 1964. The Structure and Measurement of Physical Fitness.
Englewood Cliffs, NJ: Prentice-Hall.

Gardner JMM, Grantham-McGregor SM. 1994. Physical activity, undemutrition and
child development. Proc Nutr Soc 53:241-248.

220

Goldstein MS. 1943. Demographic and Bodily Changes in Descendants of Mexican
Immigrants. Austin, TX; Institute of Latin American Studies, University of
Texas.

Gomez F. 1946. Desnutricion. Boletin Medico del Hospital Infantil 3:543-551.

Gomez F. 1956. Mortality in second and third degree malnutrition. J Trop Pediatr
2:77-83.

Gonzalez-Garcia L, Monterrubio-Gomez I. 1993. Tendencias en la dinamica y la
distribucion de la poblacion, 1970-1992. In CONAPO (Consejo Nacional de
Poblacion): El Poblamiento de Mexico. Una Vision Historico Demograﬁca.
Tomo IV. México en el Siglo XX. Hacia e1 Nuevo Milenio: El Poblamiento en
Perspectiva. México, DF: Editorial Azabache, p 154-187.

Graedon TL. 1976. Health and urban community of southern Mexico. Doctoral
Dissertation, University of Michigan, Ann Arbor.

Graham GG, Maclean WC, Kallman CH, Rabold J, Mellits ED. 1979. Growth
standards for poor urban children in nutrition studies. Am J Clin Nutr
32:703-710.

Graham GG, Maclean WC, Kallman CH, Rabold J, Mellits ED. 1980. Urban-rural
differences in the growth of Peruvian children. Am J Clin Nutr 33:338-344.

Grantham-McGregor S, Powell CA, Walker SP, Himes JM. 1991. Nutritional
supplementation, psychosocial stimulation, and mental development of stunted
children: the Jamaican study. Lancet 338:1-5.

Grantham-McGregor SM.1990. Malnutrition, mental function, and development In
RM Suskind, L Lewinter-Suskind, eds: The Malnourished Child. New York:
Raven Press, p 197-212.

Haas JD, Martinez EJ, Murdoch E, Conlisk E, Rivera JA, Martorell
R.1995.Nutritional supplementation during the preschool years and physical
work capacity in adolescents and young adult Guatemalan. J Nutr, Suppl

125:1078-1089.

Hamill PVV, Drizd TA, Johnson CL, Reed RD, Roche AF. 1977. NCHS growth
curves for children, birth-18 years. United States. DHEW Publication No.
(PHS) 78-1650. Washington, DC: US Government Printing Ofﬁce.

Hamill PVV, Johnston FE, Lemeshow S. 1972. Height and weight of children:

Socioeconomic status, United States. Vital and Health Statistics, Series 11,
No. 119.

221

Henneberg M, Louw GJ. 1998. Cross-sectional survey of growth of urban and rural
“Cape Coloured” school children: Anthropometry and functional tests. Am J
Hum Biol 10:73-85.

Himes JH, Dietz WH. 1994. Guidelines for overweight in adolescent preventive

services: Recommendations from an expert committee. Am J Clin Nutr
59:307-3 16.

Hulanicka B, Waliszko A. 1991. Deceleration of age at menarche of girls in
Poland. Ann Hum Biol 18:507-513.

INEGI (Instituto Nacional de Estadistica, Geograﬁa e Informatica). 1990. XI Censo
General de Poblacion y Vivienda. Oaxaca. Perﬁl Sociodemograﬁco.
Aguascalientes: INEGI.

INEGI (Instituto Nacional de Estadistica, Geograﬁa e Informatica). 1993. Oaxaca.
Resultados deﬁnitivos. Datos por AGEB Urbana. XI Censo General de
Poblacion y Vivienda. Aguascalientes: INEGI.

INEGI (Instituto Nacional de Estadistica, Geograﬁa e Informatica). 1998. Anuario
Estadistico del Estado de Oaxaca, Edicion 1998. Aguascalientes: INEGI.

INEGI (Instituto Nacional de Estadistica, Geografia e Informatica). 2000. ANUARIO

 

INEGI (Instituto Nacional de Estadistica, Geograﬁa e Informatica). 20013.
Estadisticas Sociodemograﬁcas (http://www.inegi.gob.mx).

INEGI (Instituto Nacional de Estadistica, Geografia e Informatica). 2001b.
Estadisticas Economicas (http://www.inegi.gob.mx).

INEGI (Instituto Nacional de Estadistica, Geografia e Informatica). 2002. Sistema

para la Consulta de Informacién Censal. Oaxaca. XII Censo de Poblacion y
Vivienda 2000. Aguascalientes: INEGI.

Instituto Nacional de Salud Publica. 2000. Encuesta Nacional de Nutricion 1999.
Tomo I. Resultados Menores de 5 Aﬁos. Cuernavaca, Morelos: Instituto
Nacional de Salud Publica.

Iraizos-Bravo A. 1999. La seguridad social y los servicios estatales de salud publica
en el ambito de la migracion interna en el Estado de Oaxaca. Coloquio nacional
sobre Politicas publicas de atencion a1 migrante, Oaxaca de Juarez, 78 Mayo,

1999. (http://www.oaxaca.gob.mx).

222

Kirkby AVT. 1973. The use of land and water resources in the past and present Valley
of Oaxaca, Mexico. Memoirs No. 5, Museum of Anthropology, University of
Michigan, Ann Arbor.

Kuczmarski RJ, Ogden CL, Grummer-Strawn LM, F legal KM, Guo SS, Wei R, Mei
Z, Curtin LR, Roche AF, Johnson CL (2000) CDC growth charts: United States.
Advance Data from Vital and Health Statistics, 314. Hyattsville, MD: National
Center for Health Statistics.

Lagunas-Rodriguez Z and J iménez-Ovando R. 1995. El crecimiento corporal de los
niﬁos y jovenes Otomies del noroeste del Estado de México. Estudios de
Antropologia Biologica V. México, DF: Universidad Nacional Autonoma de
México, p 327-348.

Lin W-S, Chen ACN, Su JZX, Zhang Y-Q, Zhu F-C, Xing W-H, Li J-Y (1992a)
Developmental perspective of pulse rate, blood pressure and vital capacity in
Chinese children. Ann Hum Biol 19:387-402.

Lin W-S, Chen ACN, Su JZX, Zhu F-C, Xing W-H, Li J-Y, Ye G-S (1992b) The
menarcheal age of Chinese girls. Ann Hum Biol 19:503-512.

Little BB, Buschang PH. Malina RM. 1988. Socioeconomic variation in estimated
growth velocity of school children from a rural subsistence agricultural
community in southern Mexico. Am J Phys Anthrop 76:443-448.

Lohman TG. 1994. Body composition. In JR Morrow, HB Falls, HW Kohl, eds: The
Prudential Fitnessgram: Technical Reference Manual. Dallas, TX: Cooper
Institute for Aerobics Research, p 57-72.

Lohman TG, Roche AF, Martorell R, eds. 1988. Anthropometric Standardization
Reference Manual. Champaign, IL: Human Kinetics.

Lopez E, Altamirano ME. 1999. Diagnostico de Salud Participativo. Santo Tomas
Mazaltepec, Etla, Oaxaca.

Lopez-Alonso S. 1995. Estudio antropobiologico en tres comunidades de la Sierra
Norte del Estado de Puebla. Crecimiento Fisico y variabilidad morfosomatica.
Doctoral dissertation. Universidad Nacional Autonoma de México.

Malina RM. 1975. Anthropometric correlates of strength and motor performance.
Exerc Sport Sci Rev 3:249-274.

Malina RM. 1982. Human biology of urban and rural communities in the Valley of

Oaxaca, Mexico. In Wolanski N, ed: Ekologia Populacji Ludzkich. Wroclaw,
Poland: Ossolineum, Wydawnictwo Polskiej Akademii Nauk, p 469-503.

223

Malina RM. 1983. Growth and maturity proﬁle of primary schoolchildren in the
Valley of Oaxaca, Mexico. Garcia de Orta Serie Antropobiologia, Revista Do
Instituto De Investigacao Cientiﬁca Tropical (Lisboa) 3 (1-2) p 153-158.

Malina RM. 1990. Crescimento de criancas Latino-Americanas comparacoes entre os
aspectos socio-economicos, urbano-rural and secular comparisons. Revista
Brasileira de Ciencia e Movimiento 1: 46-75.

Malina RM. 1994a. Anthropometry, strength and motor ﬁtness. In SJ Ulijaszek, CGN
Mascie-Taylor, eds: Anthropometry: The Individual and the Population.
Cambridge, UK: Cambridge University Press, p 160-177.

Malina RM. 1994b. Physical activity: Relationship to growth, maturation, and
physical ﬁtness. In C Bouchard, RJ Shephard, T Stephens, eds: Physical
Activity, Fitness, and Health. Champaign, IL: Human Kinetics, p 918-930.

Malina RM. 1995a. Anthropometry. In PJ Maud, C Foster, eds: Physiological
Assessment of Human Fitness. Champaign, IL: Human Kinetics, p 205-219.

Malina RM. 1995b. Physical activity and ﬁtness of children and youth: Questions
and implications. Med, Exerc, Nutr, Health 4:123-135.

Malina RM. 1999. Secular change in size, strength and motor ﬁtness in the Valley of
Oaxaca, Mexico. National Science Foundation, Grant No. BCS-9816400.

Malina RM. 2002. Secular change in size, strength and motor ﬁtness in the Valley of
Oaxaca, Mexico. Report of activities and results of the research supported by
National Science Foundation, Grant No. BCS-9816400.

Malina RM, Bouchard C. 1991. Growth, Maturation and Physical Activity.
Champaign, IL: Human Kinetics Publishers.

Malina RM, Buschang PH. 1985. Growth, strength and motor performance of
Zapotec children, Oaxaca, Mexico. Hum Biol 57:163-181.

Malina RM, Buschang PH, Aronson WL, Selby HA. 1982. Childhood growth status
. of eventual migrants and sedentes in a rural Zapotec community in the Valley
of Oaxaca, Mexico. Hum Biol 54:709-716.

Malina RM, Himes JH, 1977. Seasonality of births in a rural Zapotec municipio,
1945-1970. Hum Biol 49:125-137.

Malina RM, Himes JH, Stepick CD, Gutierrez Lopez F and Buschang P. 1981.

Growth of rural and urban children the Valley of Oaxaca, Mexico. Am J Phys
Anthrop 55:269-280.

224

Malina RM, Himes JH, Stepick CD. 1976. Skeletal maturation of the hand and wrist
in Oaxaca school children. Ann Hum Biol 3:211-219.

Malina RM, Katzmarzyk PT. 1999. Validity of the body mass index as an indicator of
the risk and presence of overweight in adolescents. Am J Clin Nutr 70: 131$—
136$.

Malina RM, Little BB, Buschang PH, DeMoss J, Selby H. 1985. Socioeconomic
variation in the growth status of children in a subsistence agricultural
community. Am J Phys Anthrop 68285-391.

Malina RM, Little BB, Shoup RF, Buschang PH. 1987. Adaptive signiﬁcance of
small body size: strength and motor performance of school children in Mexico
and Papua Guinea. Am J Phys Anthrop 73: 489-499.

Malina RM, Little BB. 1985. Body composition, strength and motor performance in
undernourished boys. In RA Blinkhorst, HCG Kemper, WHM Saris, eds:
Children and Exercise XI. Champaign, IL: Human Kinetics, p 293-300.

Malina RM and Selby HA. 1982. Zapotec restudy: A ten year follow-up of Zapotec
children. Report of activities and results of the research supported by National
Science Foundation grant BSN 78-10642, submitted to the National Science
Foundation, July 1, I982.

Malina RM, Selby HA, Buschang PH Aronson WL, Wilkinson RG. 1983. Adult
stature and age at menarche in Zapotec-speaking communities in the Valley of
Oaxaca, Mexico, in secular perspective. Am J Phys Anthrop 60:437-449.

Malina RM, Selby HA, Buschang PH Aronson WL. 1980. Growth status of school
children in a rural Zapotec community in the Valley of Oaxaca, Mexico, in
1968 and 1978. Ann Hum Biol 7:367-374.

Malina RM, Selby HA, Swartz LJ. 1972. Estatura, peso, circunferencia del brazo en
una muestra transversal de niﬁos zapotecos de 6 a 14 aﬁos. Anales de
Antropologia, 9: 143-155.

Martinez-Julian S, Hemandez-Barroso G, Canseco-Pacheco MT. 2001. Diagnostico
de Salud 2001. Servicios de Salud de Oaxaca. Jurisdiccion Sanitaria No. 1.
Valles Centrales, Santo Tomas Mazaltepec, Oaxaca, Mexico.

Martinez-Morales O. 1999. Diagnostico de Salud 1999. Servicios de Salud de
Oaxaca. Jurisdiccién Sanitaria No. l. Valles Centrales, San Juan Chapultepec,

Oaxaca. México.

Martorell R. 1989. Body size, adaptation and function. Hum Org 48:15-20.

225

Martorell R. 1995. Results and implications of the INCAP follow-up study. J Nutr
Suppl 125:1127-1138.

McCullough JM. 1982. Secular trend for stature in adult male Yucatec Maya to 1968.
Am J Phys Anthrop. 58:221-225.

Mebrahtu S, Pelletier D, Pinstrup-Andersen. 1995. Agriculture and nutrition. In P
Pinstrup-Andersen, D Pelletier, H Alderman, eds: Child Growth and Nutrition
in Developing Countries: Priorities for Action. Ithaca, NY: Cornell University,
p 220-242.

Meredith HV. 1979. Comparative ﬁndings on body size of children and youths living
at urban centers and in rural areas. Growth 4:95-104.

Meredith HV. 1982. Research between 1950 and 1980 on rural-urban differences in
body size and growth rate of children and youths. Adv Child Develop Behav
17283-138.

Miernik Z. 1965. Sprawnosc ruchowa chlopcow z miast i ze wsi w wieku 7.5-15.5 lat
(Motor ﬁtness of boys 7.5-15.5 years of age from the city and country).
Rocznik Naukowy, Wyzsza Szkola Wychowania Fizycznego w Krakowie 4:75-
113 (in Polish).

Molina V. 1991. La migracion indigena y sus efectos al interior de la comunidad de
origen. In A Castellanos Guerrero, G Lopez Rivas (coordinadores): Etnia y
Sociedad en Oaxaca. México, DF: Universidad Autonoma Metropolitana,
Escuela Nacional de Antropologia e Historia, Instituto Nacional de
Antropologia e Historia, p 71-80.

Munetaka H, Matsuura Y, Munetaka H. 1971. On the study of the differences in
motor ability of children between three different communities: Island, housing
development and urban area. Res J Phys Educ 16:91-97 (in Japanese).

Murphy AD, Stepick A. 1991. Social Inequality in Oaxaca: A History of Resistance
and Change. Philadelphia: Temple University Press.

de Onis M, Blossner M. 1997. WHO Global Database on Child Growth and
Malnutrition. Geneva: World Health Organization, WHO/NUT/77.4.

de Onis M, Blossner M. 2000. Prevalence and trends of overweight among preschool
children in developing countries. Am J Clin Nutr 72:1032-1039.

de Onis M, Monteiro C, Akre J, Cugson G. 1993. The worldwide magnitude of

protein-energy malnutrition: an overview from the WHO Global database on
child growth. Bull WHO 71:703-712.

226

Palma-Cabrera JL. 1993. La planeacion demograﬁca en el marco de la actual politica
de poblacion. In: CONAPO. El Poblamiento de México. Una Vision Historico
Demograﬁca. Tomo 1V. México en el Siglo XX. Hacia el nuevo milenio: El
poblamiento en perspectiva. México: Azabache, p 126-153.

Pan American Health Organization. 1994. Nutritional situation in the Americas.
Epidemiological Bulletin, Pan American Health Organization 15: 1-6.

Pawloski LR. 2002. Growth and development of adolescent girls from the Segou
region of Mali (West Africa). American Journal of Physical Anthropology
117:364-372.

Peﬁa Reyes, ME. 1992. Aplicacion del método F els para evaluar la maduracion del
esqueleto en un grupo niﬁos de Oaxaca. México, DF: Instituto Nacional de
Antropologia e Historia, Serie Antropologia Fisica.

Peﬁa Reyes ME, Cérdenas Barahona EE, Cahuich MB, Barragan A, Malina RM.
2002. Growth status of children 6-12 years of age from two different
geographic regions of Mexico. Ann Hum Biol 29:11-25.

Peﬁa Reyes ME, Cérdenas Barahona EE, Lamadrid PS, del Olmo Calzada M, Malina
RM. In preparation. Growth and nutritional status of children 6-13 years of age
in theTarahumara Sierra, northern Mexico.

Peﬁa Reyes ME, Malina RM, Little BB, Buschang P. 1995. Consumo de Alimentos
en una comunidad rural Zapoteca en el Valle de Oaxaca. In: Ramos RM, Lopez
S, editors, Estudios de Antropologia Biologica, México DF, Instituto Nacional
de Antropologia e Historia p 407-414.

Perez-Hidalgo C, Chavez A, F ajardo LJ. 1965. Peso y talla en un grupo de niﬁos de
diferente nivel socioeconomico. Salud Publica de México. Epoca V, Vol. VII,
No. 4. Julio-Agosto, p 535-541.

Perez-Ortiz B, Mora H. 1967. Somatometria en escolares de Tlaltizapan, Morelos.
Bol Méd Hosp Inf (México) 24: 291-307.

Pilicz S, Sadowska J. 1973. Z badan nad rozwojem i sprawnoscia ﬁzyczna mlodziezy
szkol podstawowych (Research on development and physical ﬁtness of primary
school children). Wychowanie Fizyczne i Sport 1:3-10 (in Polish).

Plowman SA, Corbin CB. 1994. Muscular strength, endurance, and ﬂexibility. In
JR Morrow, HB Falls, HW Kohl, eds: The Prudential Fitnessgram: Technical
Reference Manual. Dallas, TX: Cooper Institute for Aerobics Research, p
73-99.

227

Pollitt E, Golub M, Gorman K, Grantham-McGregor S, Levinsky D, Schurch B,
Strupp B, Wachs T. 1996. A reconceptualization of effects of undemutrition on
children’s biological, psychosocial and behavioral development. Social Policy
Reports 10:1-21.

Popkin B, Richards MK, Monteiro CA. 1996. Stunting is associated with overweight

in children of four nations that are undergoing the nutrition transition. J Nutr
126:3009-3016.

Powell CA, Grantham-McGregor S. 1985. Ecology of nutritional status and
development in young children in Kingston, Jamaican. Am J Clin Nutr
41:1322-1331.

Powell CA, Walker SP, Himes JM, Fletcher PD, Grantham-McGregor S. 1995.
Relationships between physical growth, mental development and nutritional

supplementation in stunted children: the Jamaican study. Acta Paediatr 84:22-
29.

Pryor HB, Thelander HE. 1972.Growth comparisons of urban and rural children in
southern Mexico with randomly selected California Children. Clin Pediat 11:
411-416.

Pyle WH. 1920. A manual for the mental and physical examination of school
children, revised. The University of Missouri Bulletin 21 (Extension Series 29):
13-25.

Ramos Galvan R. 1960. Somatometria. In Diagnostico, Actualizaciones en Pediatria.
Sextas Jomadas de la As Med del Hosp. Inf Mex Pub AMHIM.

Ramos Galvan R. 1975. Somatometria Pediétrica. Estudio semilongitudinal en niﬁos
de la ciudad de México. Archivos de Investigacion Médica 6:83-396.

Ramos Galvan R, Luna-Jaspe H 1964. Somatometria en tres mil niﬁos de la clase
media de la ciudad de México. (b) estudio del crecimiento ﬁsico de un grupo de
nifios considerados norrnales en relacion a los promedios norteamericanos. Bol
Med Hosp. Inf de Mex 21 :65-78.

Rangel E, Mascarenas A, Bosques F. 1993. Frecuencia de sobrepeso en una poblacién
adolescente de regiomontanos. IV Simposio de Investigacion en Pediatria ‘Dr.
Joaquin Cravioto,’ Monterrey, N.L., México.

Reyes-Castellanos S, Cruz-Sénchez L, Canseco-Pacheco MT. 2000. Diagnostico de

Salud 2000. Servicios de Salud de Oaxaca. Jurisdiccion Sanitaria No. l. Valles
Centrales, Santo Tomas Mazaltepec, Oaxaca, Mexico.

228

Reyes-Castellanos S, Rojas AL, Canseco-Pacheco MT. 1999. Diagnostico de Salud
1999. Servicios de Salud de Oaxaca. Jurisdiccion Sanitaria No. l. Valles
Centrales, Santo Tomas Mazaltepec, Oaxaca, Mexico.

Richardson SA, Birch HG, Grabie E, Yoder K. 1972. The behavior of children in
school who were severely malnourished in the ﬁrst two years of life. J Health
Soc Behav 13: 276-284.

Rios Morales M. 1995. Zapotecos de los Valles Centrales. 1n Instituto Nacional
Indigenista: Valles Centrales. Etnografia Contemporanea de los Pueblos
Indigenas de México. México, DF: Instituto Nacional Indigenista, Secretaria de
Desarrollo Social.

Rocha-Ferreira MB, Malina RM, Rocha LL. 1991. Anthropometric, functional and
psychological characteristics of eight-year-old Brazilian children from low
socioeconomic status. In Shephard RJ, Parizkova J, eds: Human Growth,
Physical Fitness and Nutrition. Basel Kager, p 109-118.

Roldan JA, Chavez A, Avila A, Muﬁoz M, Alvarez MA, Ledesma JA. 2000. La
Desnutricién a Nivel Municipal en México: De Acuerdo a un Indicador Mixto
de Estado Nutricional. México, DF: Instituto Nacional de Nutricién Salvador
Zubiran.

Safrit JM. 1995. Complete Guide to Youth Fitness Testing. Champaign, IL: Human
Kinetics.

Satyanarayana K, Naidu AN, Rao NBS. 1979. Nutritional deprivation in childhood
and late body size, activity, and physical work capacity of young boys. Am J
Clin Nutr 32:1769-1775.

Schell L, Smith MT, Bilsborough A. 1993. Human biological approaches to the study
of third world urbanism. In L Schell, MT Smith, A Bilsborough, eds: Urban
Ecology and Health in the Third World. Cambridge: Cambrigde University
Press, p 1-9.

Schroeder DG, Martorell R. 1999. Fatness and body mass index from birth to young
adulthood in a rural Guatemalan population. Am J Clin Nutr 70(suppl):137S-
1448.

Schroeder DG, Martorell R, Flores F. 1999. Fatness and fat distribution in
Guatemalan adults. Am J Epidemiol 149:177—185.

Scrimshaw NS. 1996. Nutrition and health from womb to tomb. Nutrition Today, 31
(2)255-67.

229

Secretaria de Salubridad y Asistencia. 1999. Informacion basica del estado de
Oaxaca. Sistema Nacional de Salud, www.ssa.gob.mx/mapas/mapas95/oax/
oaxaca.htm.

Secretaria de Salud. 1998. Aspectos relevantes sobre la estadistica de deﬁciencias de
la nutricion. Salud Publica de México 40: 206-214.

Selby HA, Murphy AD. 1979. The City of Oaxaca. Final Technical Report, Ofﬁce of
urban Development, Technical Assistance Bureau, Agency for International
Development, Washington, DC.

Shephard RJ. 1978. Human Physiological Work Capacity. Cambridge: Cambridge
University Press.

Siegel SR. 1999. Patterns of sport participation and physical activity in urban
Mexican youth. Doctoral dissertation, Michigan State University, East Lansing.

Simons J, Beunen G, Ostyn M, Renson R, Swalus P, Van Gerven D, Willems E. 1969.
Construction d’une batterie de tests d’aptitude motrice pour garcons de 12 a 19
ans, par la methode de l’analyse factorielle. Kinanthropologie 1:323-362.

Spurgeon JH, Meredith HV, Onhuoha GBI, Giese WK. 1984. Somatic ﬁndings at age
9 years on three ethnic groups of Nigerian urban and rural boys. Growth 48:
176-186.

Spurr GB. 1990. The impact of chronic undemutrition on physical work capacity and
daily energy expenditure. In GA Harrison, JC Waterlow, eds: Diet and Disease
in Traditional and Developing Societies. Cambridge: Cambridge University
Press, p 24-61.

Spurr GB, Reina JC, Barac-Nieto M. 1983. Marginal malnutrition in school-aged
Colombian boys: anthropometry and maturation. Am J Clin Nutr 37:119-132.

Spurr GB, Reina JC. 1988. Patterns of daily energy expenditure in normal and
marginal undernourished school-age Colombian children. Eur J Clin Nutr

42:819-834.

Spurr GB, Reina JC. 1989. Maximum Oxygen consumption in marginally
malnourished Colombian boys. Am J Hum Biol 1:11-19.

Stonich SC. 1993. I Am Destroying the Land. The Political Ecology of Poverty and
Environmental Destruction in Honduras. Boulder, Co: Westview Press.

Tamura Y. 1975. Physical ﬁtness of rural adolescents. In K Asahina, R Shigiya, eds:
Human Adaptability. Volume 4. Physiological Adaptability and Nutritional

230

Status of the Japanese. B. Growth, Work Capacity and Nutrition of Japanese.
Tokyo: University of Tokyo Press, pp 50-61.

Tanner JM, Eveleth PB. 1976.Urbanization and growth. In: Harrison GA, Gibson JB,
editors, Man in Urban Environments. Oxord: University Press, p 144-166.

Triana-Tejas A, Wyatt C, Ramirez MJ. 2001. Prevalence of undemutrition and iron
deﬁciency in preschool children from different socioeconomic regions in the
city of Oaxaca, Oaxaca, Mexico. J Nutr Sci Vitaminol 47:47-51.

Trowbridge FL, Marks J S, Lopez de Romana G, Madrid S, Boutton TW, Klein PD.
1987. Body composition of Peruvian children with short stature and high
weight-for-height as an indicator of nutritional status. Am J Clin Nutr 46:411-
418.

Valladares I, Coelho M. 1993.Urban research in Latin America: Towards a research

agenda. Discussion paper series No. 4 (http://www.unescg.org/most/
valleng.htm).

van Wierigen, JC Wafelbakker F, Verbrugge HP, Haas JH. 1971. Growth Diagrams
1965 Netherlands. Groningen, The Netherlands: Wolters-Noordof.

Vega-Franco L, Robles-De la Vega B. 1962. Evaluacion del estado nutricional en
escolares de la ciudad de Durango. Salud Publica de México Epoca V, 4:385-
396.

Villanueva M. 1979. Adiposidad, muscularidad y linearidad en un grupo de niﬁos
Mexicanos de distintos niveles socioeconémicos. Anales de Antropologia 16:
407-432.

Walker SP, Grantham-McGregor S, Himes JH, Williams S. 1996. Adolescent
Kingston girls’ school achievement: nutrition, health and social factors. Proc
Nutr Soc 55:333-343.

Waterlow JC, Buzina R, Keller W, Lanes JM, Nichaman MZ, Tanner JM. 1977. The
presentation and use of height and weight data for comparing the nutritional
status of children under the age of 10 years. Bull World Health Org 55:489-498.

Waterlow J S. 1993. Reﬂections on stunting. In C Gopalan, ed: Recent Trends in
Nutrition. Delhi: Oxford University Press, p 18-34.

Welte CR. 1973. Population selected Localidades in the Valley of Oaxaca (censuses

of 1960 and 1970). Oaxaca de Juarez, México: Oﬁcina de Estudio de
Humanidad del Valle de Oaxaca.

231

Whiteford S, Ferguson A.1991. Social dimensions of food security and hunger: An
overview. In S Whiteford, A Ferguson, eds: Harvest of Want: Hunger and Food
Security in Central America and Mexico. Boulder, CO: Westview Press, p 1-22.

WHO (World Health Organization). 1995. Physical status: The use and interpretation
of anthropometry. Report of a WHO expert committee. Geneva: WHO No. 854.

Wilson D. 1993. Theoretical approaches to Mexican labor migration. Latin American
Perspectives, Issue78z20-129.

Winick M. 1993. Malnourished Children in United States. New York: Springer.

Wyatt CJ, Triana-Tejas MA. 2000. Nutrient intake and growth of preschool children

from different socioeconomic regions in the city of Oaxaca, Mexico. Ann Nutr
Metab 44: 14-20.

232