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This is to certify that the

thesis entitled

MUSCLE MOVEMENT PATTERN OF THE SELECTED
EXTENSORS DURING PRONE HIP HYPEREXTENSION

presented by

Jolynn Marie-Canfield Nelson

has been accepted towards fulfillment
of the requirements for

M ' S ' degree in
Education and Exercise Science

Physical

 

 

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MUSCLE MOVEMENT PATTERN OF THE SELECTED EXTENSORS
DURING PRONE HIP HYPEREXTENSION

By

J olynn Marie-Canfield Nelson

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Physical Education and Exercise Science

I997

ABSTRACT

MUSCLE MOVEMENT PATTERNS OF THE SELECTED
EXTENSORS DURING PRONE HIP HYPEREXTENSION

By

Jolynn M.C. Nelson

The purpose of this study was to examine the onset times of contractions of the
hamstrings, gluteus maximi, and lumbar paraspinal muscles during active prone hip
hyperextension to assess if these muscle groups contracted in a consistent sequence. Nine
subjects, each of whom had no history of back pain, participated in the control group. Six
subjects, each of whom had a history of back pain, comprised the experimental group.
Potential subjects participated in a clinical screening to rule out weakness in the legs due
to neurologic problems. Each subject performed 10 repetitions of prone hip
hyperextension on each side. The onset times of contraction were recorded
electromyographically for bilateral hamstrings, gluteus maximi, lumbar erector spinae,
and thoracic erector Spinae during each trial. Order of muscle firing was examined within
and between groups. Descriptive statistics were used to examine the variability that
occurred in the pattern of muscle firing in both groups, since no consistent pattern of
muscle firing was found in either group. Additionally, the multiple firings of single

muscle groups within single trials were recorded and described.

ACKNOWLEDGMENTS

I would like to thank the Automotive Systems Group of Johnson Controls,
Inc. for the use of their Myosystem 2000 EMG equipment.

I am also indebted to Dr. Dianne Ulibam', Ph.D., Department of Physical
Education and Exercise Science, for her guidance, assistance, and
encouragement throughout my Master’s Degree program. Thanks are
expressed to Sue Kevem and the members of my graduate committee for the
time and effort they put in to helping me finish this project.

Additionally, many thanks to all members of my family for “putting up”

with me and providing constant support.

TABLE OF CONTENTS

CHAPTER 1

INTRODUCTION ........................................................................................ 1
Need for Study ......................................................................................... 3

CHAPTER 2

LITERATURE REVIEW .............................................................................. 5

CHAPTER 3

METHODS AND MATERIALS ................................................................ 12
Subjects .................................................................................................. 13
Materials ................................................................................................ 16
Research Design ..................................................................................... 17
Variables ................................................................................................ 18
Experimental Procedures ........................................................................ 18
Limitations ............................................................................................. 23

CHAPTER 4

RESULTS AND DISCUSSION ................................................................. 24

CHAPTER 5

CONCLUSIONS ........................................................................................ 43

LIST OF REFERENCES ............................................................................ 50

APPENDICES ............................................................................................ 52
Appendix A ........................................................................................... 52
Appendix B ........................................................................................... 66

Appendix C ........................................................................................... 68

Appendix D ........................................................................................... 70
Appendix E ........................................................................................... 71
Appendix F ........................................................................................... 72
Appendix G ........................................................................................... 73

LIST OF TABLES

Table 1 - Study Participants Demographics ................................................. 25
Table 2 - Participant Mobility ...................................................................... 26
Table 3 - Experimental Group: Short-Form McGill Pain Questionnaire ....... 27

Table 4 - Subject 101 Sequence of Right Hip Hyperextension From Prone
Position ....................................................................................................... 29

Table 5 - Subject 106 Sequence of Right Hip Hyperextension From Prone
Position ....................................................................................................... 3 1

Table 6 - Right Hip Hyperextension for Subject 201 of Experimental
Group .......................................................................................................... 34

Table 7 - Median Muscle Firing Sequence for the Left Hip
Hyperextension-Control Group .................................................................... 35

Table 8 - Percent Occurrence of Median Muscle Contraction-Left Hip
Hyperextension-Control Group .................................................................... 3 7

Table 9 - First Five Trials vs. Second Five Trials for Hamstrings During
Prone Hip Hyperextension - Control & Experimental Groups ...................... 41

vi

LIST OF FIGURES

Figure 1 - Subject 101 Median Values for Left Hip Hyperextension vs.
Predicted Sequence ..................................................................................... 36

Figure 2 - Median Sequence for Lefi Hamstring During Left Hip
Hyperextension - Control ............................................................................ 3 8

Figure 3 - Median Sequence of Left Gluteus Maximus During Lefi Hip
Hyperextension-Control .............................................................................. 39

Figure 4 - Trunk Flexion and Extension Using an Inclinometer ................... 74

vii

CHAPTER 1

INTRODUCTION

Low back pain is one of the most challenging and frequent diagnoses
treated within the field of Physical Therapy. The majority of studies have
found that 60-90% of the population experience low back pain at some point
during their lives (Biering-Sorenson, 1984; Svensson, Vedin, Wilhelmsson,
and Andersson, 1983). Physical therapists use a variety of exercises to
strengthen the tnmk and improve posture as part of the treatment for patients
experiencing low back pain. A common intervention utilized by physical
therapists is the strengthening of the muscles that provide trunk and hip
extension and maintain erect posture. Usually, when instructing patients in
performing the motion of hip hyperextension, therapists focus on how high
the leg should be raised from the table, or how much resistance the patient
could tolerate, rather than determining if this individual uses a compensatory
strategy to perform the movement. More recent education has focused on the

idea that the continued cycle of back pain may be a result of impairments in

the sequence of muscle firing. It was noted by Janda (1985) that
postural/tonic muscles respond to dysfunction by facilitation, hypertonicity,
and shortening. He also noted that phasic muscles respond to dysfunction by
inhibition and weakness. As a result of these responses, these involved
muscles no longer respond to movement in the same fashion, thus resulting in
what is called muscle imbalance.

The initiation of hip hyperextension is brought about by a contraction
of the hamstrings and gluteus maxirnus muscles, followed by activation of
the contralateral and ipsilateral trunk extensors (J anda, 1985). This
movement pattern is important in maintaining the correct position of the
pelvis. If there is an alteration of this movement pattern, for example, a
muscle in the sequence is inhibited and does not contract, muscular
compensation will occur. As a result of the compensatory muscle action,
somatic dysfunction can occur due to overuse of particular muscle groups.
Also, if there were an alteration of this movement pattern, pain usually will
result because of the compensatory strategy being utilized, in addition to
somatic dysfunction. If the faulty pattern continues undiagnosed and
untreated, the amount of hip extension would be reduced and compensated

for by a change in the position of the pelvis, resulting in low back pain.

Need for Study:

Currently, muscle sequencing is not routinely assessed in the majority
of low back evaluations. If muscle sequencing is evaluated, it may or may not
be performed correctly, or consistently, between medical professionals.
Therefore, there is a need to develop a valid, reliable, and objective
measurement which can be performed in a clinical setting. Problematic,
however, is that there is not an abundance of information regarding the
analysis of movement patterns and their role in low back somatic
dysfunction. With the continued development of methods to better measure
muscular system balance, the treatment and prevention of chronic back pain
may be better addressed.

The purpose of this study was to examine the onset times of
contraction of the hamstrings, gluteus maximi, and lumbar paraspinal
muscles during active prone hip hyperextension, to see if these muscles were
recruited in a consistent sequence. The formal research hypotheses that were
tested in this study were as follows:

1. There will not be a statistically significant difference in the order of
muscle firing of the ipsilateral hamstrings, ipsilateral gluteus maxirnus,

contralateral lumbar erector spinae muscles, and ipsilateral lumbar erector

spinae muscles in participants of the control group during prone hip
hyperextension.

2. There will not be a statistically significant difference in the order of
muscle firing of the ipsilateral hamstrings, ipsilateral gluteus maximus,
contralateral lumbarerector spinae muscles, and ipsilateral lumbar erector
spinae muscles in participants of the experimental group during prone hip
hyperextension.

3. A statistically significant difference will not exist in the muscle
firing order of the ipsilateral hamstrings, ipsilateral gluteus maximus,
contralateral lumbar erector spinae muscles, and ipsilateral lumbar erector

spinae muscles between the control and experimental groups.

CHAPTER 2

LITERATURE REVIEW

Resisted strength testing has been the most widely taught and utilized
tool of muscle functioning during prone hip hyperextension in the field of
Physical Therapy. Janda and Jull (1987) and Lewit (1991) described the
assessment of prone hip hyperextension as a movement by more than the
gluteus maximus. They reported that movements, such as hip extension, were
not just performed by a single muscle group, but rather, these movements
were performed by a number of muscle groups. In the case of hip extension,
J anda and Jull (1987) discussed a previous, but not published, study where
Janda used electromyography to illustrate that the prime mover of hip
hyperextension was the hamstrings group along with contributions from the
gluteus maxirnus and the lumbar erector spinae muscles. The movement

pattern found in the unpublished study by Janda which was discussed by

Janda (1985) and Janda and Jull (1987), was that the hamstrings contracted
initially, followed immediately by the ipsilateral gluteus maximus, the
ipsilateral lumbar erector spinae muscles, and lastly, by the contralateral
lumbar erector spinae muscles. Janda and Jull (1987) observed that muscles
reacted in a fairly consistent manner to dysfunction. They believed muscles
either respond to dysfunction by over activation and tightness, or by
inhibition and weakness. Those muscles that they described as responding to
dysfunction by becoming tight and over active are called postural muscles.
The postural muscles are described by Bookhout (1992) as muscles that
maintain postural balance and are active during most movement patterns to
provide stability. Conversely, the phasic muscles are involved in making the
movement occur. Phasic muscles respond to dysfunction via inhibition and
weakness. Janda and Jull (1987) classified the iliopsoas, hamstrings, and
lumbar erector spinae muscles as postural in nature, therefore prone to
tightness. They placed the gluteus maximus, medius, and minimus as phasic
muscles, thus muscles prone to inhibition. The words phasic and tonic used
to describe these two groups, neither correspond to the conventional

description of muscle fiber types, nor to histological studies.

Janda and Jull (1987) believed that low back pain may be a symptom
of muscle firing imbalance. They described the "pelvic crossed syndrome" as
an imbalance which existed between hyperactive, tight hip flexors and
lumbar erector spinae muscles, and relatively weakened gluteal and
abdominal muscles. The resultant posture can negatively affect static and
dynamic functioning. Lewit (1991) concluded that an increased load on the
lumbar spine occurred while standing with the described pelvic crossed
syndrome posture. This posture would be created by an increased lumbar
lordosis, due to tight hip flexors and lumbar erector spinae muscles, and
weak abdominal muscles. He continued to relate this posture to a dynamic
situation, such as walking, stating that active hip extension was not executed
by the inhibited gluteus maximus, but rather by the tight, hyperactive lumbar
erector spinae. The activation of the hyperactive lumbar erector spinae
resulted in hyperlordosis instead of extension of the hip. Ultimately, this
scenario causes increased strain on the lumbar spine in the sagittal plane due
to hypermobility of the lumbar spine.

Pierce and Lee (1990) utilized electromyography (EMG) to study
twenty healthy subjects to determine if a statistically consistent sequence of

muscle activation could be observed during prone right hip extension from a

position of thirty degrees of flexion. The subjects were taught the movement
and examined while moving their leg at a velocity of 30° per second. They
concluded from their study that sequencing of muscle firing during this
motion was extremely variable at both the individual and group levels. They
were able to conclude that the biceps femoris was activated prior to the onset
of hip extension, and this was the only consistent muscle firing pattern noted
in their study.

Pierce and Lee (1990) felt that there was a varied amount of hip
extension motion past the neutral position. Therefore, those participants who
lacked hip range of motion beyond neutral would be performing trunk
hyperextension during the prone leg lifting, to compensate for this lack of hip
movement. It was difficult to conclude whether or not a consistent muscle
firing pattern existed from the study by Pierce and Lee (1990), since they did
not measure the same activity as described by J anda and Jull (1987).

Singer (1987) examined the musculoskeletal status of thirty-five
physiotherapy students. The evaluation of muscle fimctioning included prone
hip extension as described in the writings of J anda (1985) and J anda and Jull
(1987). The purpose of Singer’s (1987) study was to develop assessment

skills, design an assessment sequence for data collection, and devise a

recording form. Using observation and palpation skills and the technique
described by J anda and Jul] (1987), the components of the assessment
examined were posture, joint restriction, and muscle function. As part of the
muscle fimction evaluation, Singer (1987) examined prone hip extension, and
used palpatory and observational skills to assess firing sequence. Exact
details regarding how he noted sequence of muscle firing utilizing palpatory
and observational skills were not described in Singer’s methodology portion
of his research. Singer concluded from his study that this process of palpating
while simultaneously observing hip hyperextension was functional and
efficient. Singer also found that most of the students had restriction in the
postural muscles used during locomotion. Also, this group of students with
postural muscle restrictions had the most pronounced lumbar lordosis,
reduced active trunk flexion, demonstrated tightness of the iliopsoas and
hamstring muscles, and weakness of the abdominal and gluteal musculature.
This pattern, described by J anda and Jull (1987) was called the pelvic crossed
syndrome. Although the students were diagnosed with pelvic crossed
syndrome, none of them were experiencing low back pain at the time of the

study.

10

A study by Jonsson (1970) investigated the function of the multifidi,
longissimus, and iliocostalis muscles at different lumbar levels during a
variety of movements. One of the movements J onsson investigated was hip
hyperextension in a prone position. He found that there was no significant
difference in the EMG activity of the erector spinae muscle between lifting
the ipsilateral or contralateral leg from the bed. Although Jonsson’s study did
not examine sequence of muscle firing, it illustrated symmetry of movement
within a subject.

Overall, there was not an abundance of research that directly studied
the sequence of muscle activation during prone hip hyperextension within a
population of people without back/ spine problems, or within a population of
individuals who have experienced back/spinal problems. The research that
has been completed thus far has had discrepancies in the methodology that
made it difficult to compare consistencies of muscle firing sequence involved
during prone hip hyperextension. Also, there has not been any research
located which investigated the sequence of muscle firing during prone hip
hyperextension in individuals with back/spinal pain. Research which

addressed the sequence of muscle firing would be of meaningful in the

ll

rehabilitation of individuals with back pain. A study of this nature would add

significantly to the existing literature pertaining to this tOpic.

CHAPTER 3

METHODS and MATERIALS

The purpose of this study was to use electromyography (EMG) to
examine the contraction onset times of the hamstrings, gluteus maximi, and
lumbar paraspinal muscles during prone active hip hyperextension, to
determine if these muscles were recruited in a consistent sequence. Two
subject groups were studied, one with back pain and one without. It was
postulated that the control group would perform hip hyperextension in the
following muscle firing order: ipsilateral hamstrings, gluteus maximus,
contralateral lumbar erector spinae muscles, and ipsilateral lumbar erector
spinae muscles.

This chapter is divided into the following sections: subjects, materials,

experimental procedures, research design, and variables.

12

13

Subjects:

Nine volunteers were selected for the control group. Members of this
group had no progressive history of back/spine pain or traumatic injury to
their backs/spines, no past surgeries of any kind, and no central nervous
system or neuromuscular disorders. The subjects of the control group had full
active trunk range of motion, a negative modified Thomas test, and
hamstrings and erector spinae lengths within the normal limits. Additionally,
leg length differences, using both the true and apparent methods, were less
than one centimeter. Each member of the control group also had to score
fifieen on the McGill Short-Form Pain Questionnaire (Melzack 1987). The
McGill Short-Form Questionnaire was utilized to quantify pain. This is an
accepted instrument, commonly given and well known in the field of
Physical Therapy. A score of 15 indicates no pain present, while a score of
sixty on this questionnaire is the highest rank of perceived pain.

Six members were selected for the experimental group fiom a group of
subjects who were referred to this study by a physician who conducted a
physical evaluation on each potential subject. Members of this group had
some degree of back pain and/or leg pain. The degree of back/spine pain was

quantified by using the McGill Short-Form Pain Questionnaire. Subjects did

14

not present with any neurologic deficit of leg weakness and did not need to
have normal trunk range of motion. The members of the experimental group
had no history of back surgery, nor were they in active treatment for their
back problem. Additionally, the flexibility of bilateral erector spinae,
iliopsoas, and hamstring muscles did not have to be within a normal range.
Finally, the measure of the true and apparent leg lengths did not have to be
less than one centimeter.
The pre-screening that was performed on subjects in both the control
and experimental groups consisted of:
1. Active trunk range of motion: flexion, extension and lateral flexion
using an inclinometer and method described by Mayer (1985).
Appendix G.
2. Modified Thomas test: assessment of iliopsoas length described by
Kendall and McCreary (1983). Appendix G.
3. Hamstring length: measured by a straight leg lift in supine position
described by Kendall and McCreary (1983). Appendix G.
4. Lumbar erector spinae: measured by long sitting toe touch

described by Kendall and McCreary (1983). Appendix G.

15

5. True leg length: measured using the technique described by
Hoppenfeld (1976). A True Leg Length is a measure of actual
length of the leg from the anterior superior iliac crest to the medial
malleolus. Appendix G.

6. Apparent leg length: measured using the technique described by
Hoppenfeld (1976). The Apparent Leg Length is an assessment of
the leg measuring from the umbilicus to the medial malleolus.
Apparent leg length takes the entire pelvis into the evaluation, and
when measured bilaterally, can be an indicator of pelvic obliquity.
Pelvic obliquity results when one side of the innominant is rotated
anteriorly or posteriorly. Pelvic obliquity can result in somatic
dysfunction of the pelvis, sacrum, and/or the lumbar spine.
Appendix G.

7. McGill Short: Form Pain Questionnaire - Melzack (1987).
Appendix F.

There were fifteen subjects, although originally it was thought that

thirty-forty subjects could be found. The time commitment of two hours was
a factor which limited a large number of volunteers from a pool of potential

subjects.

16

Materials:

1.

Inclinometer: an instrument used to measure degrees of movement.
The inclinometer was used to measure the active trunk ranges of
motion of: trunk flexion, extension, and lateral flexion, and
hamstring flexibility. A reliability test was performed prior to
gathering data for this study, to determine repeatability of results
using the inclinometer by this researcher. The reliability of this
researcher was high (r = .94 for lateral flexion; r = 1.0 for flexion;

r = 1.0 for extension).

. Tape measure: an instrument used to measure length. The tape

measure was used to measure true and apparent leg lengths and

hamstring and erector spinae lengths.

. Surface self-adhering disposable electromyography electrodes that

were pregelled. Paper tape was used to ensure adherence to skin
during motion.

Physiograph: device used for recording EMG signals. A sixteen
channel Myosystem 2000 electromyography unit, manufactured by
Noraxon, was used.

Alcohol pads: used to clean skin for electrode placement.

17

6. 4x4 Cotton Gauze: used to abrade skin for better contact of

electrodes for electrical impulses.

7. Disposable razor: used to shave area of electrode placement.

8. Disposable gloves.

9. McGill Short-Form Pain Questionnaire: A questionnaire designed

to quantify degree of back pain.

10. A light with a hand switch.

11. A clock with a second hand.

Research Design:

The experiment began with a Repeated Measures Design. The
following hypotheses were tested.

Hypothesis 1: There will not be a statistically significant difference in
the order of muscle firing of the ipsilateral hamstrings, ipsilateral gluteus
maximus, contralateral lumbar erector spinae muscles, and ipsilateral lumbar
erector spinae muscles in participants of the control group during prone hip
hyperextension.

Hypothesis 2: There will not be a statistically significant difference in
the order of muscle firing of the ipsilateral hamstrings, ipsilateral gluteus

maximus, contralateral lumbar erector spinae muscles, and ipsilateral lumbar

18

erector spinae muscles in participants of the experimental group during prone
hip hyperextension.

Hypothesis 3: A statistically significant difference will not exist in the
muscle firing order of the ipsilateral hamstrings, ipsilateral gluteus maximus,
contralateral lumbar erector spinae muscles, and ipsilateral lumbar erector
spinae muscles between the control and experimental groups.

Variables:

The independent variable was sequence of muscle firing (S.O.F.),
while the dependent variables were the results of muscle contraction onset
times were recorded electromyographically.

Experimental Procedures:

When the subjects first arrived at the laboratory, they were asked to
read and sign an informed consent form (copy in Appendix E). The
procedures used in this study were approved by the University Committee on
Research Involving Human or Animal Subjects. In addition, each subject was
verbally reminded that they could stop their participation in the study at any
time.

A pre-screen assessment was performed on all subjects to determine if:

for the control group, each subject met the criteria of the control group, and

".

19

to establish a baseline for members of the experimental group. Demographic
information regarding gender, age, history of past surgeries, and presence of
back/spine and/or radicular pain was collected (Appendix D). The McGill
Short-Form Pain Questionnaire was administered to each subject (Appendix
F). Standing active trunk flexion, extension, and lateral flexion (Mayer, 1985)
were tested as part of screening. The Modified Thomas test, hamstring
flexibility (straight leg measurement), and long-sitting test for hamstrings and
erector spinae muscle length (Kendall and McCreary, 1983) were
administered. A description of the pre-screen objective measures is in
Appendix G. True and apparent leg length measurements were also a part of
the pre-screen assessment. Two leg length measures were obtained and
compared.

Each subject changed into shorts in the dressing room. They returned
to the testing area and were instructed to lie prone on a plinth. The researcher
identified the motor points of bilateral biceps femoris, gluteus maximi, and
lumbar erector spinae muscles at two levels (T12-Ll and L3-L4) using a
written description of their location, a pictorial chart, and palpation. The site

of each electrode was placed at a location half of the distance between the

20

motor point and the musculotendinous insertion of each particular muscle
group (Basmajian and DeLuca, 1985).

Examination gloves were worn by the researcher during subject
preparation and exit procedures. The site for electrode placement was
prepared first by shaving it with a disposable razor, cleaning it with isopropyl
alcohol, and then abrading the skin by rubbing cotton gauze over it to ensure
adequate surface contact and to reduce skin resistance. The positive electrode
was placed on the selected site parallel to the longitudinal axis of the muscle
fibers. The negative electrode was placed directly next to the positive
electrode. A ground electrode was applied to the acromion process on the
right shoulder. All of the electrode wires were secured using paper tape. The
electrode wires were then connected to the eight channels of the EMG
system. The wire connected for the switch to elicit the trigger was also linked
to the EMG system. The EMG system was used to simultaneously monitor
surface electrode activity of bilateral hamstrings, gluteus maximi, lumbar
erector spinae muscles, and thoracic paraspinal muscles.

Each subject was asked to perform leg raises while in the prone
position. They were instructed to keep the leg being assessed straight at the

knee, while hyperextending it at the hip. In addition, they were instructed to

21

hyperextend the leg, as fast as possible, once the cue to elicit movement had
been provided. The cue to raise the leg as fast as possible was given to get an
automatic motor response. A visual demonstration of the prone hip
hyperextension was provided by the researcher. After the demonstration, the
researcher verified if the subject understood the activity, if not, it was re-
demonstrated until the directions were understood. The subject practiced the
activity ten times on each side. A minute rest period was provided before the
actual data were gathered. For easy visual observation, a light was located in
at eye level in front of each subject. Triggering of the light cued the subject to
hyperextend at the hip as fast as they were able. Reaction time was not a
consideration in this study as only the muscle firing sequence was of interest.
A random sequence of rest times between trials was established prior to
gathering the subject data to maintain consistency between subjects and to
decrease anticipation. The maximum rest period was 60 seconds and the
minimum rest period was 15 seconds. A rest occurred between each
repetition until EMG silence was noted on the screen. Afier the rest period,

the subject performed five trials of hip hyperextension, beginning with the

right hip.

22

The order of data collection with random rest periods between trials

are listed below:

Trial - right l_e_g with rest mriod. Trial - left lgg with rest period.

 

One Six
}15 seconds }25 seconds
Two Seven
}55 seconds }60 seconds
Three Eight
}50 seconds }55 seconds
Four Nine
}40 seconds }40 seconds
Five Ten
Eleven Sixteen
}60 seconds }20 seconds
Twelve Seventeen
}50 seconds }30 seconds
Thirteen Eighteen
}20 seconds }60 seconds
Fourteen Nineteen
}55 seconds }50 seconds
Fifteen Twenty

Once the five repetitions were completed with the right leg, five repetitions
were completed on the left, five more on the right, and an additional five on
the left, for a total of twenty trials. Electromyographic data were recorded by
the physiograph during each of the ten trials on each extremity. The
triggering of the light also was recorded by the physiograph.

When all the signals were collected, the researcher removed the
electrodes from the subject, and returned the subject to the dressing room.
The subject was thanked for their participation and was informed that upon

completion, study results would be available upon request.

23

Originally, this study was to be analyzed as a repeated measures
design, with the muscle firing (S.O.F.) identified as the independent variable.
However, due to the results, the performance of inferential statistics was
deemed to be inappropriate.

Limitations:

Internal sources that limited this study included testing, EMG
methodology, and subject selection. Testing was limiting because the
subjects, instructed to raise their leg a total of ten times each side, could have
become “test-wise”, potentially impacting their performance. An error in the
electrode placement and skin preparation, may also have contributed to error
in the overall results. Because the subjects were all volunteers, the selection
of subjects of the study may have been limited. Finally, subject selection for
the experimental group was limited due to incidences of back pain and
possible reluctance to hyperextend quickly.

External sources of limitation included the Hawthorne effect and
pretest effects. The special attention given each member of the study may
have altered the subjects’ performances (Hawthorne effect). Since there was
a period of practice to teach the movement that was to occur, a pretest effect

could have impacted the performances of the subjects.

CHAPTER 4

RESULTS AND DISCUSSION

Fifteen volunteer subjects participated in this study. The participants in
the experimental group were chosen because they had a history of back pain,
some of the subjects experienced leg pain, and they were evaluated by a
physician who had ruled out any muscle weakness due to a neurologic
deficit. The six members of the experimental group participated in this study
before being actively involved in treatment. The control group participants
were selected because they had: no history of progressive back/spine
problems, apparent and true leg length discrepancy no greater than one
centimeter, no past surgeries of any kind, no central nervous system or
neuromuscular disorders, a score of 15 on the McGill Short- Form Pain
Questionnaire (Melzack, 1987), and a normal level of mobility based on the
pre-screen battery. The age range of subjects in the experimental group was
27-45 years. The control group ages ranged from 23-41 years. The median

ages were comparable between the two groups, with the experimental median

24

25

age of 38.5 years, and the control group median of 35 years. Gender
composition of the experimental group was three females and three males.
The gender breakdown in the control group was five females and four males.
The study demographics are shown in Table 1. Although the design of the
study was for ten subjects in each group, the time commitment of two hours
was a restrictive factor eliminating a large number of volunteers from the

pool of potential subjects.

TABLE 1. STUDY PARTICIPANTS DEMOGRAPHICS
r-xr'riumnru. (ovum.

AGE

27 - 45 23 - 41
Median . 38.5 35
Mean 37 33.22
GENDER
Female 3 5
Male 3 4

 

Median trunk ranges of motion were utilized in order to establish a
level of functional mobility as a criterion required to participate in the control
group. It was noted that the motions of trunk flexion and right and left lateral
flexion were similar between the experimental and control groups, while
there were greater differences in trunk extension. The control group had a

measure of 24° for their median value, and the experimental group had 55°

for their median measure of trunk extension, a difference of 185° between

26

the two groups, with the experimental group having less movement in trunk
extension. F urtherrnore, flexibility involving the hamstrings was examined to
ascertain that each subject demonstrated normal hip movement. The
hamstring flexibility measures were found to be 7° higher for the control
group for each side. Means were included in the parentheses to the right of
the median in Table 2. Overall, with the exception of trunk extension, the two

groups were comparable. See Table 2 for these results.

TABLE 2. PARTICIPANT MOBILITY

 

 

 

 

 

 

 

 

 

MEDIAN RANGE OF EXPERIMENTAL CONTROL
MOTION

Trunk flexion (mean) 27.17° (29°) 30° (34.11°)
Trunk Ext. (mean) 5.5° (11.l7°) 24° (22.22°)

Trunk sidebending right (mean) 7° (783°) 8° (822°)
Trunk sidebending left (mean) 9° (11.67°) 10° (13.33°)

HAMSTRING FLEXIBILITY

Right (mean) 66° ( 67.83°) 73° (71.44°)
Left (mean) 68°( 65°) 75° (76.1 1°)

 

 

 

 

Right and left measures were equal for each of the true and apparent
leg lengths in the control group and for four of the six members of the
experimental group. One subject in the experimental group had a 1.8
centimeter difference between the right and left true leg length measurements,
while the apparent measures were equal. The differences in length found in

this subject could indicate a difference in the boney structure of the leg, since

27

the difference was found in the true leg length measures only. The remaining
subject presented with a 0.4 centimeter asymmetry with the true leg length
measure and a 1.0 centimeter difference in the apparent leg length measure.
Pelvic obliquity may be indicated by the greater difference in apparent leg
length measures. Pelvic obliquity could interfere with the orientation of the
muscles around the pelvis, therefore, possibly resulting in altered muscle
firing.

Results of the McGill Short-Form Pain Questionnaire in the
experimental group had scores ranging from 18 - 40, with a median score of
26. These scores translated into the participants of the experimental group
having a mild amount of pain at the time of testing. See Table 3 for
individual scores for the experimental group. Since all the members of the
control group had a score of fifteen, their scores were not included in this

table.

TABLE 3. EXPERIMENTAL GROUP: SHORT - FORM McGILL PAIN

 

 

, UESTIONNAIRE
[ 201 202 203 204 205 206 MEDIAN MEAN J
[SCORE 40 19 18 35 23 29 26 27.33 |

 

 

 

 

 

 

 

 

 

The EMG data were collected from a sixteen channel Myosystem 2000
electromyography (EMG) unit. The results were analyzed for the onset time

of each muscle group using Myosoft software. The settings for the onset time

28

analysis were onset time of ten and subsist time of five. Readings were
analyzed for order of firing and patterning, both within and between groups.
When examined, the data were not normally distributed, which rendered any
parametric statistical analyses inappropriate. In addition, non-parametric
statistics were attempted, but were not able to be performed on the data due
to the lack of consistent pattern of muscle firings. Therefore, the results of
this study were descriptive in nature.

EMG readings for bilateral hamstrings, bilateral gluteus maximi,
bilateral lumbar paraspinal muscles, and bilateral thoracic paraspinal muscles
were recorded and examined for the order of firing. All participants in both
groups illustrated a degree of variability within subjects. Surprisingly,
multiple firings of single muscle groups were observed during the prone hip
hyperextension. Moreover and most critically, the expected sequencing of
firing was not observed for any subject in either the control or experimental
group.

All subjects in the control group demonstrated inconsistent order of
muscle firing. As an illustration of the inconsistencies within the control
group, the sequence of muscle firing for prone right hip hyperextension

during the ten trials for Subject 101 are shown in Table 4. The variability in

29

sequencing of muscle contractions for each of the ten trials is illustrated. All
of the muscles connected with electrodes to the EMG and the trigger are
displayed. Trial 101-l versus Trial 101-5 both had the trigger occur first, the
right lumbar paraspinal muscles contracted third, and the left lumbar
paraspinal muscles contracted fifth. All other muscle groups contracted at
different times.

An example of multiple firings of a muscle group within a trial, also is
illustrated in Table 4. Trial four (101-4) represents a multiple firing of the
right thoracic paraspinal muscles. It was noted that for this subject during
right hip hyperextension, there was only one incidence of multiple firings of a
single muscle group, that being the thoracic paraspinal muscles, which
contracted twice in Trial 101-4. Unexpected multiple contractions of the

same muscle group occurred within trials for most subjects.

TABLE 4. SUBJECT 101 SEQUENCE OF RIGHT HIP HYPEREXTENSION
FROM PRONE POSITION

 

 

 

 

 

 

 

 

 

 

 

 

TRIAL 101—1 101-2 101-3 101-4 101-5 101-6 101-7 101-8 101-9 101-10
TRIG 1 l l 2 l l l l l l
R TH-I 9 6 3 l 4 4 7 7 7 7
R TH-Z O O 0 8 0 0 0 0 0 O
L TH 6 5 7 7 2 6 4 3 3 4
R LUM 3 3 4 5 3 3 6 6 6 2
L LUM 5 7 5 6 5 5 3 5 4 5
R MAX 4 4 6 4 7 8 9 8 8 8
L GMAX 8 9 9 9 9 7 5 4 5 6
R HAM 2 2 2 3 6 9 8 9 9 9
L HAM 7 8 8 0 8 2 2 2 2 3

 

 

 

 

 

 

 

 

 

 

 

KEY: TRIO-TRIGGER R "is RIGHT THORACIC PARASPINALS L The LEFT THORACIC PARASPINALS R Lum-
RIGHT LUMBAR PARASPINALS L LUM- LEFT LUMBAR PARASPINALS R cm- R GLUTEUS MAXIMUS LM:
LEFT GLUTEUS MAXIMUS any: RIGHT HAMSTRING L HAMILEFT HAMSTRING

 

30

As an example of the range of inconsistencies within individuals of
the control group, the sequence of muscle firings for the right leg during the
ten trials for Subject 106 are shown in Table 5. Incidents of multiple firings
were observed in both the experimental and control groups: Subject 106 had
the most incidences of multiple firings of single groups of muscles within a
trial, for any subject. The variability in sequencing of muscle contractions for

each of the ten trials is illustrated in Table 5.

31

TABLE 5. SUBJECT 106 SEQUENCE OF RIGHT HIP HYPEREXTENSION

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FROM PRONE POSITION
TRIAL l 2 3 4 5 6 7 8 9 10
TRIG 2 l 2 2 3 3 l 4 2 l
RTHI 1 6 3 l l l 2 l 4 5
RTHZ 8 0 8 3 5 6 6 6 O 10
RTH3 0 0 0 0 O 12 12 l l 0 l4
RTH4 0 0 0 0 0 l3 l7 0 O 17
RTHS 0 O 0 0 0 0 l9 0 0 I9
RTH6 0 0 0 0 O 0 21 0 0 23
RTH7 O 0 0 0 0 O O 0 0 27
RTH8 0 0 0 0 0 0 O 0 0 32
LTHI 4 3 5 4 8 7 3 3 1 3
LTHZ O 0 0 0 O 9 7 10 6 7
LTH3 0 0 O O 0 14 10 12 0 20
LTH4 0 0 O 0 0 15 18 0 O 25
LTHS 0 O 0 O O 0 20 0 O 28
RLUMI 5 5 7 7 2 2 5 2 5 6
RLUMZ 0 0 0 O 4 l l 13 8 0 9
RLUM3 0 0 O 0 0 l6 l6 0 O 12
RLUM4 0 0 O 0 0 18 22 0 0 l6
RLUMS 0 0 0 0 0 O 0 0 0 18
RLUM6 O 0 0 0 0 0 0 O O 22
RLUM7 0 O O O O 0 0 0 O 26
RLUM8 0 O 0 O 0 0 0 O O 3 l
LLUMl 6 4 8 8 7 5 4 5 7 2
LLUM2 9 0 0 0 O 10 O 0 0 1 l
LLUM3 0 0 0 0 O 0 O 0 0 15
LLUM4 0 0 0 O 0 0 0 O 0 21
LLUMS O 0 O 0 O 0 O 0 O 24
LLUM6 0 0 0 0 0 0 O O 0 29
RMAXI 7 8 6 6 10 8 9 9 O 8
RMAXZ 10 0 0 0 0 l7 1 1 l3 0 I 3
RMAX3 O 0 O 0 0 l9 l4 0 0 0
LMAXI l l 7 9 9 9 4 8 7 3 4
LMAXZ O 0 O 0 O 0 15 O 0 30
RHAM 3 2 l 5 6 20 23 14 O 33
LHAM 0 O O 0 0 0 O O O 0

 

 

 

 

 

 

 

 

 

 

 

 

 

KEY: IBIOI'TRIGGER R THS RIGHT THORACIC PARASPINALS L THS LEFT THORACIC PARASPINALS M
RIGHT LUMBAR PARASPINALS L LLIM=ll LEFT LUMBAR PARASPINALS R GMAXII R GLUTEUS MAXIMUS M
LEFT GLUTEUS MAXIMUS BM: RIGHT HAMSTRING L HAMBLEFT HAMSTRING

32

Specifically, if one were to examine Trial 2 versus Trial 7 for Subject

106 below, the following muscle firing orders were illustrated:

TRIAL 2 TRIAL 7
Trigger Trigger
Right Hamstring Right Thoracic-l
Left Thoracic Left Thoracic-l
Left Lumbar Left Lumbar
Right Lumbar Right Lrunbar-l
Right Thoracic Right Thoracic-2
Left G. Max Left Thoracic-2
Right G. Max Left G. Max-l
Right G. Max-l
Left Thoracic-3
Right G. Max-2
Right Thoracic-3
Right Lumbar-2
Right G. Max-3
Left G.Max-2
Right Lumbar-3
Right Thoracic-4
Left Thoracic4
Right Thoracic-5
Left Thoracic-5
Right Thoracic-6
Right Lumbar-4
Right Hamstring
"”" Number at side indicates the number of times this muscle
group fired.

The right hamstring muscles fired second in Trial 2 which was anticipated.
The right gluteus maximus muscle was eighth to fire, compared to the
predicted third. The left lumbar paraspinal muscles in Trial 2 were fourth and
had been predicted to be fourth. Lastly the right lumbar paraspinal muscles
were, as predicted, at fifth. Trial 7 was markedly different from Trial 2.
Subject 106 was an excellent example of multiple firing as well. These

multiple firings of muscle groups for Subject 106 are illustrated for all trials

33

in Table 5. Trial 7 had three contractions of the right gluteus maximus, four
of the right lumbar paraspinal muscles, and six of the right thoracic
paraspinal muscles. The total muscle contractions in Trial 2 were eight, while
in Trial 7, there were 23 muscle contractions for the same motion. Contrary
to research (J anda, 1985; Lewit, 1991; Singer, 1987) and clinical
observation, consistent sequential muscle firing did not occur in any trial for
any subject investigated. Moreover, as multiple contractions were not
addressed in the literature, these types of contractions were unexpected. All
results of the individual muscle firing sequences are contained in Appendix
A for both the control and experimental groups.

Within the experimental group, subjects confirmed the research
hypothesis that they would not use the order of muscle firing of ipsilateral
hamstring, ipsilateral gluteus maximus, contralateral lumbar paraspinal
muscles, and ipsilateral lumbar paraspinal muscles. An example of the
random sequence of muscle contractions that were recorded during prone hip
hyperextension for Subject 201 of the experimental group is illustrated in
Table 6. The remaining individual results of the experimental group are in
Appendix A. This random pattern of muscle firings is consistent with the

observations made in the clinic and in the literature (Greenman and

Bookhout, 1993; Bookhout, 1992), in which treatment of individuals with

back pain was discussed. No multiple firings were recorded for Subject 201.

TABLE 6. RIGHT HIP HYPEREXTENSION FOR SUBJECT 201 OF
EXPERIMENTAL GROUP

 

 

 

 

 

 

 

 

 

 

TRIAL 201-1 201-2 201-3 201-4 201-5 201-6 201-7 201-8 201 -9 20! ~10
TRIG l 3 l l 2 2 1 l 1 l
R TH 4 1 4 3 3 3 3 2 3 3
L TH 5 5 7 4 7 7 4 4 4 8

R LUM 3 2 3 5 4 8 7 7 7 7

L LUM 6 6 5 7 6 5 6 6 6 5

R MAX 7 0 6 6 5 0 0 0 0 O

L MAX 0 0 0 0 0 6 8 8 8 6

R HAM 2 4 2 2 l l 2 3 2 2

L HAM 0 0 0 0 0 4 5 5 5 4

 

 

 

 

 

 

 

 

 

 

 

 

 

KEY: TRIGsTRIGGER R TH= RIGHT THORACIC PARASPINALS L TH: LEFT THORACIC PARASPINALS R Lug
RIGHT LUMBAR PARASPINALS I_. LUM: LEFT LUMBAR PARASPINALS R GMAX- R GLUTEUS MAXIMUS L cw:
LEFT GLUTEUS MAXIMUS R HAM= RIGHT HAMSTRINGL_HAu_-LEFT HAMSTRING

The median values for each muscle’s firing sequence for all trials of
right and left hip hyperextensions trials were examined in both the control
and experimental groups. The calculation of the median muscle firing
sequence was performed to determine if subjects within a group had a
consistent pattern, other than the one hypothesized for the control group. The
median pattern of muscle order firing of the ten trials for the control group
during left hip hyperextension is shown in Table 7. It was noted that there
was not a consistent sequence that occurred for the control group. The only
consistent result was that the trigger occurred first with all subjects, except
Subject 106. Additionally, the median sequence of muscle firing for each

subject in the experimental group was found to be inconsistent with the group

35

as a whole. Since the results were inconclusive, with no pattern of muscle
firing order emerging, the median firing sequence data for both sides for the

control and experimental group were placed in Appendix B.

TABLE 7. MEDIAN MUSCLE FIRING SEQUENCE FOR THE LEFT HIP
HYPEREXTENSION - CONTROL GROUP

 

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From Table 7, Subject 101’s median sequence of muscle firings was
compared with the expected sequence of muscle firings to illustrate a
representation of this variability of muscle firings. This information is
presented in Figure l. The blue color indicated the predicted pattern of firing.
Because this example was the left hip which hyperextended, the left
hanrstring, left gluteus maximus, right lumbar paraspinal muscles, and left
lumbar paraspinal muscles were expected to fire, respectively. The purple
color represented the median sequence of muscle firing for Subject 101

during left hip hyperextension. The trigger was first, left hamstring fired

 

36
second, the same as the predicted order. Firing of remaining muscle groups
did not occur in the predicted sequence.

FIGURE 1.

SUBJECT 101 MEDIAN VALUES FOR LEFT HIP
HYPEREXTENSION VS. PREDICTED SEQUENCE

 

IPREDICT
I
insuauec
,, L.

FIRING SEQUENCE

 

 

 

TRIG L GMAX R LUM L LUM
MUSCLES

Further evaluation of the data was performed to examine the percent of
time a particular muscle group contracted in a particular sequence position.
The results of the left hip hyperextension continued with the same
inconsistent pattern. The trigger occurred first 89% of the time. The left
hamsuing was second or sixth at 33% and third 22%, left gluteus maximus
was seventh at 44%, left lumbar paraspinal muscles fourth at 55%, and right
lumbar paraspinal muscles occurred fifth at 55%. The anticipated sequence

did not occur. A complete tabulation of median sequence of percent

 

occurrence for the control group’s left hip hyperextension is presented in

37

Table 8. Further charts of percent occurrence of muscle firings for right and

left hip hyperextensions for both the control and experimental groups are in

Appendix C.

TABLE 8. PERCENT OCCURRENCE OF MEDIAN MUSCLE CONTRACTION -

LEFT HIP HYPEREXTENSION-CONTROL GROUP

 

 

 

 

 

 

 

 

 

 

 

 

SEQUENCE TRIGGER 1. rpm R LIAM L CMAX R GMAX L LUM g LUM r. TI_I R ril-
0 0 1136 0 0 0 0 O 2236 O
1 8936 0 0 0 0 0 0 1136 1136
2 1136 3336 1136 1136 0 0 1136 1136 2236
3 O 2236 1136 0 0 3336 1136 1136 3336
4 O O 1136 0 0 5536 2236 O 2236
5 0 0 1136 0 0 1136 5536 2236 0
6 0 3336 3336 1136 3336 0 0 1136 1136
7 0 0 2236 4436 5536 0 0 1136 0
8 0 O 0 3336 1136 0 0 0 0
9 0 O O O 0 0 0 0 0

 

 

 

 

 

 

 

 

 

 

 

KEY: T___RIG=TRIGGER R THa RIGHT THORACIC PARASPINALS L ___T__Hl LEFT THORACIC PARASPINALS M

RIGHT—— LUMBAR PARASPINALS _L____ LUM- LEFT LUMBAR PARASPINALS R ems aR GLUTEUS MAXIMUS gm
LEFT GLUTEUS MAXIMUS R HAM: RIGHT HAMSTRINGLMLEFT HAMSTRING

 

Following are exemplary pie charts, included to further illustrate
percentage of occurrence of the median muscle firing pattern for an
individual muscle in one of the tested groups. For the control group’s left hip
hyperextension, the median occurrences of firing for the left hamstring were
almost equal at second at 34% and sixth at 33% of the time, as seen in Figure
2. It was expected that the left hamstring would fire second after the trigger

had signaled the subject to lift their leg.

38

FIGURE 2.

MEDIAN SEQUENCE FOR LEFT HAMSTRING DURING LEFT
HIP HYPEREXTENSION - CONTROL

11% Random

33% Sixth

34%Second

 

22% Third

The percentage of times the left gluteus maximus fired in a particular
order during left hip hyperextension is shown in Figure 3. The left gluteus
maximus contracted in almost equal proportions at second (11%) and sixth
(11%) and at seventh (45%) and eighth (33%). Although, the prediction for
contraction of the left gluteus maximus muscle was for it to contract third, it
can be seen that within the control group, the median firing order for the left

gluteus maximus was not primarily third for any individual.

39

FIGURE 3.

MEDIAN SEQUENCE OF LEFT GLUTEUS MAXIMUS DURING
LEFT HIP HYPEREXTENSION - CONTROL

11%Sixlh

   

33% Eighth 11% Second

45% Seventh

A trend was noted in the first five trials versus the second five trials of
hip hyperextension in the sequence of contraction of the right hamstring
muscles. The median values for timing of the contractions of the right and
left hamstrings for the control subjects (101-109) and the experimental
subjects (201-206) were illustrated in Table 9. The subject numbers were
placed in the first column. The median hamstring values were arranged with
the first and second set of five trials for the right leg adjacent to each other in
columns two and three, respectively. A similar arrangement for the median
hamstring muscle values for the left leg were placed in the fourth and fifth
columns, respectively. It was anticipated that the hamstrings would contract
second, immediately following the trigger. As seen in Table 9, for subjects of

the control group during right hip hyperextension, the median sequence of

40

firing for the hamstrings was two for three participants, three for three
participants, and five for three participants. There was a change which
occurred in the second set of five repetitions, in that the firing occurred later
in the sequence. The median sequence of firing was seven for one
participant, eight for three participants, nine for four participants, and twenty
for one participant. Similar results were noted during right hip
hyperextension for participants of the experimental group. The median
sequence for the right hamstrings during the first five repetitions was two for
two participants, three for one participant, five for one participant, and six for
two participants. The second set of five repetitions based on the median
sequence of firing was zero for two participants, two for one participants,
seven for one participant, and eight for two participants. Initially it was
thought that fatigue may have played a role in the later set of contractions for
the right hamstrings during right hip hyperextension. However, when the
median values for the left hamstrings were examined, the results were not
similar to the right side. For the left hamstrings, the median scores for the
first set of repetitions were higher than the median values for the second set
of repetitions, indicating later firings of the muscles for the first set of

repetitions. These findings for the left hamstrings were in opposition to the

41

findings for the right hamstrings. Data were verified for correct order of
repetitions. It was unknown what caused this apparent switch in firing order,
but merits further investigation. Contributing factors may include fatigue, leg

dominance, and stabilization by the opposite leg.

TABLE 9. FIRST FIVE TRIALS VS. SECOND FIVE TRIALS FOR
HAMSTRINGS DURING PRONE HIP HYPEREXTENSION - CONTROL &

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EXPERIMENTAL GROUPS
SUBJECT 1.1 FIVE TRIALS 2nd FIVE TRIALS 1.: FIVE TRIALS 2nd FIVE TRIALS
RIGHT LEG RIGHT LEG LEFT LEG LEFT LEG
101 2 9 s 2
102 s s 9 3
103 3 9 9 3
104 5 9 9 3
105 2 s s 3
106 3 20 0 0
107 3 7 7 2
100 2 s 0 2
109 s 9 o 2
201 2 2 0 4
202 0 0 9 3
203 2 0 0 3
204 5 s 6 2
205 3 7 s 2
206 s a 9 s

 

 

 

 

 

 

 

 

Overall, and contrary to research and clinical observation, no ordered
sequence of muscle firing was recorded for either the control or experimental

groups. Furthermore, multiple contractions of single muscle groups within

42

trials occurred. These multiple firings of single muscle groups within a trial
were not addressed in the literature. Additionally, muscle fatigue may have
played a role in the variability seen in the sequence of firing, but it was

difficult to measure in the current design of this study.

CHAPTER 5

CONCLUSIONS

Patterning of muscle firing is important in retraining individuals who
present with symptoms of back pain, lumbosacral somatic dysfunction, and
postural changes due to muscle tighmess and muscle weakness. Improper
sequencing of muscle firing when performing prone hip hyperextension has
ramifications functionally in walking. It is believed by this researcher that
during gait, when hip extension past neutral occurs, individuals who have
inhibited components of the pattern studied, may also lack the ability to
perform portions of the gait cycle correctly. What most probably results are
compensatory patterns to allow for walking to be as functional as possible. If
the most functional pattern of muscle firing for hip extension past neutral can
be identified, people with back pain can be further served. Prone hip

hyperextension at high speed to assess differences in order of sequencing that

44

might occur within groups and between groups was examined in this study.
No pattern of muscle firing sequencing was found within or between groups.
As no consistent muscle firing order within a group could be determined,
differences in the muscle firing order of the ipsilateral hamstrings, ipsilateral
gluteus maximus, contralateral lumbar erector spinae muscles, and ipsilateral
lumbar erector spinae muscles between the control group and experimental
group could not be statistically substantiated.

Because of this finding, inferential statistics could not be performed
since the hypotheses addressed differences in patterning of muscle firing
sequence. Instead, a descriptive analysis was performed.

The muscle firing order during active prone hip hyperextension was
remarkably variable both within and between subjects of the control group.
Because of these results, the research hypothesis that stated there would not
be a statistically significant difference in order of muscle firing by
participants during prone hip hyperextension, could not be rejected. This
finding of variability did concur with other research (Pierce, et a1., 1990)
addressing prone hip extension.

The speed with which the motion was performed may have impacted

the pattern of movement. The subjects were all instructed to lift the leg as

45

quickly as they could, once they saw the trigger. Watson (1996) and
Greenman and Bookhout (1993), noted that there becomes less time for
feedback loops to occur from the afferent system, therefore, the postural
muscles do not have the time to react. Since the phasic muscles do not rely on
a feedback system, they can react faster. The reasoning presented in the
literature could account for the variability found in this study. Pierce and Lee
(1990) reported that the variability in muscle firing order in their study may
have been a result of the slow hip extension movement (approximately
30°/second). The information provided in the Pierce and Lee (1990) study
lends support that the speed of movement and muscle firing sequencing at the
hip needs to be further investigated.

In addition, variability of muscle firings for active prone hip
hyperextension within and between subjects of the experimental group were
found. In this instance, the research hypothesis stated that there would not be
a statistically significant difference in the order of muscle firing of the
ipsilateral hamstrings, ipsilateral gluteus maximus, contralateral lumbar
erector spinae muscles, and ipsilateral lumbar erector spinae muscles in

participants of the experimental group during prone hip hyperextension. This

46

hypothesis could not be rejected. Inability to reject this hypothesis was based
on the absence of consistent pattern of muscle firings in either group.

The third hypothesis, that no difference in the muscle firing order of
the examined muscles would exist between the control and experimental
groups, could not be rejected. Inability to reject this hypothesis was based on
the absence of consistent pattern of muscle firing in either group.

Multiple firings were not expected to occur during the movement of
hip hyperextension. A possible explanation for their occurrence could be due
to the amount of hip hyperextension a subject was allowed to perform. The
EMG signals were collected from the time the muscle initiated the leg
movement, and the leg was returned to the plinth. The actual magnitude of
hip hyperextension was not controlled between subjects, or between trials for
each subject. The varied degrees of hip movement may explain why some
subjects demonstrated multiple firings. For example, a subject could have
extended their hip higher than actual joint movement allowed by further
extending their trunk. This trunk extension may have elicited additional
contraction of muscles that had already contracted. Pierce and Lee, (1990)
did not report any multiple firings in their study with slow (30°/sec) limited

hip extension to 30°.

47

Clinical implications of this Study for the field of Physical Therapy
were that more research is necessary, examining the effects of varied speeds
and degree with which active prone hip hyperextension is performed.
Additionally, the examination of muscle fuing sequence timing problems,
and examination of the muscle firing patterns that result need to be
researched. It is still felt by this researcher that timing problems, especially a
lack of gluteal activation, may frequently cause persons with low back
dysfunction to perform hip hyperextension incorrectly. Lack of gluteal
contraction, in many cases, causes hypertonicity in one or both sides of the
lumbar paraspinal muscles. These individuals then present clinically with a
higher and deeper lumbar lordosis and increased anterior pelvic tilt. This
description is a component of the pelvic crossed syndrome described by
J anda and Jull (1987). It also is observed clinically, that there is a decrease in
these postural changes with training and education interventions. Training
and re-education of the pattern of muscle firings during prone hip
hyperextension described and investigated in this study have been successful
in decreasing the pelvic crossed syndrome.

It is felt that the number of subjects in this study was a limiting factor.

The fact that there were only nine in the control group and six in the

6X

“'1

 

48

experimental group limited the strength of the findings. However, at least
with the control group, a pattern of firing was expected to be found. Because
of the variability in order of muscle firing sequences and the speed of prone
hip hyperextension studied, the author suggests that more studies be
performed at different speeds and at a consistent degree of hip
hyperextension, to ascertain when the breakdown of the sequenced patterning

OCCUI'S.

 

Suggestions for further study include researching varied speeds of a
consistent amount of hip hyperextension and the patterning of muscle firings
that occurs during that motion. Muscle fatigue, leg dominance, and trunk
stabilization may have played roles in the variability that occurred.
Researchers in this area may want to consider examining fewer repetitions
and track the same movement with a day or more between trials varying
which side, right or left, begins first. The variation in which lower extremity
starts first would help resolve the question of any patterning results due to
fatigue. Additionally of interest to clinicians, would be attaching EMG
electrodes to the abdominal muscles to assess their role in lumbar
stabilization during prone hip hyperextension. Lastly, further studies to assess
patterns of muscle firing during functional movements such as forward

bending, returning to extension from forward bending, walking on varied

49

terrain, and stair climbing need to be performed. These studies should

compare asymptomatic subjects with those who have a history of back pain.

LIST OF REFERENCES

Basmajian, J. , & DeLuca, C. (1985). Muscles alive (5th ed.).
Baltimore: Williams & Wilkins.

Biering - Sorenson, F (1984). Physical measurements as risk indicators
for low-back trouble over a one year period. Spine, 2, 106-119.

Bookhout, M. (1992). Examination and treatment of muscle
imbalance. In J. Bourdillion, Spinal manipulation (5th ed.). Oxford:

Butterworth-Heineman.

 

Greenman, P. , & Bookhout, M. (1993). Exercise prescription as an
acfiunct to manual medicine. Unpublished manuscript.

Hoppenfeld, S. (1976). Physical examination of the spine and
extremities (lst ed.). London: Prentice Hall.

 

J anda, V. (1985). Rational therapeutic approach of chronic back
pain. Proceedings of the symposium chronic back pain, rehabilitation
and self help (69-74).

 

J anda, V. , & Jull, G. (1987). Muscles and motor control in low back
pain: assessment and management. In J. R. Taylor & L. T. Twomey
(Eds), Physical therapy of the low back New York:

Churchill Livingstone.

Jonsson, B. (1970). The functions of individual muscles in the
lumbar part of the spinae muscle. Journal of Electromyography, l, 5-
21.

50

51

 

Kendall, F. , & McCreary, E. (1983). Muscle testing and function
(3rd ed.). Baltimore: Williams & Wilkins.

Lewit, K. (1991). Manipulative therapy in rehabilitation of the motor
system (2nd ed.). London: Butterworth-Heinemann.

Mayer, T. (1985). Using physical measurements to assess low back
pain. Journal of Musculoskeletal Medicine, _6_,_44-59.

Melzack, R. (1987). The short-form pain questionnaire. 1331p 30,
191-197.

Pierce, M. N. , & Lee, W. (1990). Muscle firing order during active
prone hip extension. Journal of Orthopaedic and Sports Plysical

Therapy, 12, 2-9.

Svensson, H. , Vedin, A. , Wilhehnsson, C. , Andersson, G. (1983).
Low-back pain in relation to other diseases and cardiovascular risk
factors. Spine, 8, 277-285.

Singer, K. (1987). A new musculoskeletal assessment in a student
population. Journal of Orthopaedic and Sports Physical Therapy,
8,34-41.

Watson, S. (1996). Australian lumbar stabilization concepts: based on
new research findings. (lst ed.). G.N.A.

 

APPENDICES

APPENDIX A

Sequence of Individual Muscle Firing

1. Right Hip Hyperextension

 

10

 

 

 

 

 

 

 

 

 

3
5
4
8
2

 

 

; Sub'ect 101- Control

TRIAL

TRIG

 

 

R THl
R TH2
L TH
R LUM
L LUM
R GMAX
L GMAX

 

 

 

 

 

 

 

R HAM
L HAM

 

 

 

 

10

 

 

 

 

 

 

 

 

 

5
6
3

8
4

 

 

, Sub'ect 102-Control

TRIAL

 

TRIG

 

R TH
L TH
R LUM
L LUM
R GMAX
L GMAX

 

 

 

 

 

 

R HAM
L HAM

 

 

 

52

FL

 

53

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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10

 

 

 

 

 

 

 

 

 

4
5
8

7

 

Subject 104-Control

 

 

TRIAL
TRIG

RTH]

 

 

 

 

LTH
RLUM

 

 

L LUM
R GMAX
L GMAX

R HAM

L HAM

 

 

 

 

 

 

Sub'ect lOS-Control

 

10

 

 

 

 

 

 

 

 

 

7

4
3

5
6

 

 

TRIAL

 

TRIG
R THl

 

 

R TH2
L TH
R LUM
L LUM
R GMAX

 

 

 

 

 

L GMAX
R HAM

 

 

LHAM

 

 

54

 

10

10
14
17
19
23

27
32

20
25

28

12
l6
18
22

26
31

ll

15
21

24

29

13

30

33

 

 

11

10
12

13

14

 

12
l7
19
21

10
18
20

13
16
22

11

14

15

23

 

12
l3

14
15

ll

16
18

10

l7

19

20

 

10

 

 

 

 

5
0
O
0
0
0
0
0
6
9
0
0
0
0

10

11

 

 

Subject 106-Control

TRIAL

 

TRIG

 

R TH!
R TH2
R TH3
R TH4
R THS
R TH6
R TH7
R TH8
L THl
L TH2
L TH3
L TH4
L THS
R LUM]
R LUM2
R LUM3
R LUM4
R LUMS
R LUM6
R LUM7
R LUM8
L LUM]
L LUMZ
L LUM3
L LUM4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

L LUMS
L LUM6

 

 

GMAX!

 

GMAX2

 

GMAX3

 

GMAX!

 

GMAX2

 

RHAM
LHAM

 

 

 

 

 

10

 

10

 

 

 

10

 

 

 

 

10

 

 

 

 

 

 

 

 

 

 

1

4
0

7

6
10

3
0

 

Sub'ect 107-Control

[—1

L
TRIG

 

TRIA

 

 

R THl
R TH2
L TH
R LUM]
R LUM2

 

 

 

 

 

L LUM
R GMAX

 

 

GMAX]

 

GMAX2

R HAMI

 

 

R HAM2

 

LHAM

3

7
4

8
2

 

 

Sub'ect 108-Control

I—J

 

TRIAL

 

TRIG

 

R TH
L TH
R LUM
L LUM
R GMAX

LGMAX

 

 

 

 

 

 

R HAM
L HAM

 

 

 

 

56

 

10

 

 

 

10
12
16
18
13
l9

14
15
17

11

20

 

 

15

10
16

ll
12
l3
l4

 

 

10

11

 

11

10

 

0

16
O
0

11

15
5

10
0
0
0
0
O
4
O
6

2

0
0
0
O

0
8

12
13

14

 

 

Subject 109-Control

TRIAL

 

TRIG

RTHI

 

 

R TH2

 

R TH3

 

R TH4

 

R THS

 

R TH6
L TH]
L TH2
L TH3
R LUMl
R LUM2
R LUM3
R LUM4
R LUMS
R LUM6
R LU M7
L LUMl
L LUM2

RGMAX

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GMAX]

 

GMAX2

 

R HAMI
R HAM2

 

 

R HAM3
R HAM4

 

 

R HAMS
R HAM6
L HAM l
L HAM2
L HAM 3

 

 

 

 

 

L HAM4

 

 

57

11. Control Group - Left Hip Hyperextension

 

20

 

19

 

18

 

l7

 

16

 

15

 

14

10

 

13

 

12

 

ll

3

6
4

9

 

L

 

Sub’ect 101-Control

FE.

 

TRIG
R THl
R TH2

 

 

 

L TH
R LUM
L LUM

R GMAX
L GMAX
R HAM
L HAM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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20

 

l9

 

18

 

17

 

16

10

 

15

 

l4

 

13

10

 

12

 

ll

5
6
8
9
4
0

 

 

, Sub'ect 103-Control

TRIAL

 

TRIG
R THl
R TH2

 

 

 

L TH
R LUM
L LUM

R GMAX
L GMAX
R HAM]
R HAM2
L HAM

 

 

 

 

 

 

 

 

 

58

 

20

 

l9

 

l8

 

17

 

l6

 

15

 

14

 

l3

 

12

 

ll

3

7
6

9
5

 

 

‘ Sub'ect lO4-Control

TRIAL

 

TRIG

 

R TH
L TH
R LUM
L LUM
R GMAX
L GMAX
R HAM

LHAM

 

 

 

 

 

 

 

 

 

 

20

 

l9

 

l8

 

l7

 

16

 

15

 

l4

 

l3

 

12

 

11

3

2
6
7
4

 

L

 

TRIA

Sub'ect 105-Control

F—J

 

TRIG

 

R TH
L TH
R LUM
L LUM
R GMAX
L GMAX
R HAM
L HAM

 

 

 

 

 

 

 

 

 

59

Sub'ect 106-Control

 

20

10

 

19

21

10
12
17
20

13
15
16
18
22
23

19

ll

14

24

 

18

10

ll

 

17

13

11

12

14

10

 

16

ll

12

 

15

16

ll

13

14

12

10

15

 

14

11

10

 

13

10

12

ll

13

 

12

10

11

 

11

0

0
4

0
0
0

0
0

0
0
0

0
7
0
0

0

3

0
0
0

 

 

TRIAL

 

TRIG

 

RTHl

R TH2

 

 

L TH]
L TH2
L TH3
L TH4
L THE!
R LUM]

 

 

 

 

 

 

R LUM2
R LUM3
R LUM4
R LUMS

 

 

 

 

R LUM6
R LUM7
R LUM8
R LUM 9

 

 

 

 

R LUM10

 

L LUM]
L LUM2
L LUM3

 

 

 

GMAX]

 

GMAX2

 

GMAX]

 

GMAX2
L GMAX

 

 

GMAX4
R HAM]

 

 

R HAM2

 

R HAM3
R HAM4

 

 

LHAM

 

 

60

 

20

 

l9

 

18

 

17

10

 

16

 

15

 

14

10

 

13

 

12

 

11

3

4

0
5

 

 

‘ Sub'ect 107-Control

TRIAL

 

TRIG

 

RTHl

 

R TH2
L TH
R LUM]
R LUM2

 

 

 

 

L LUM

 

GMAX]

 

GMAX2

 

GMAX]

 

GMAX2

 

RHAM
LHAM

 

 

 

Sub'ect 108-Control

 

20

 

l9

 

18

 

17

 

16

 

15

 

l4

 

l3

 

12

 

11

2

7
5
8

9

 

 

TRIAL

 

TRIG

 

R TH
L TH
R LUM
L LUM

RGMAX

L GMAX

 

 

 

 

 

 

R HAM
L HAM

 

 

 

61

 

20

 

l9

 

18

 

17

 

l6

 

15

 

14

10

ll

 

13
13

10

ll

12
14
16
15
17
19
20
18

 

12

 

11

1

3

10
O

0

0
0
0
0

8
6

7

ll

5

 

 

. Subject lO9-Control

TRIAL

 

TRIG

 

R THl

 

RTH2

R TH3

 

 

R TH4

 

R TH5

 

RTH6

R TH7

 

 

RTH8

R TH9

 

 

R THIO

RTHI]

 

 

R TH12
L TH
R LUM
L LUM
R MAX

 

 

 

 

 

L MAX

 

R HAM
L HAM

 

 

 

62

HI. Experimental Group - Right Hip Hyperextension

 

 

10

 

10

11

 

10

11

 

 

 

 

10

 

 

 

l

9

5

7
8

ll

10

 

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L
TRIG

TRIA

 

 

R THl

 

RTH2

R TH3

 

 

L TH]
L TH2
L TH3
R LUM
L LUM
R GMAX
L GMAX
R HAM

 

 

 

 

 

 

 

 

LHAM

 

 

 

63

 

10

 

 

 

 

 

 

 

 

 

Sub'ect 204-Ex erimental

6
3

7
0

 

 

TRIAL

 

TRIG

 

R TH
L TH
R LUM
L LUM
R GMAX
L GMAX
R HAM

 

 

 

 

 

 

 

LHAM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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3

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2
6

 

 

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TRIAL

 

TRIG

 

RTH
LTH
RLUM
LLUM

RGMAX

L GMAX

 

 

 

 

 

 

R HAM
L HAM

 

 

 

64

 

 

 

20

 

 

 

19

ll

20

 

 

 

18

19

 

 

 

17

10

18

 

 

 

16

10

17

 

 

 

15

16

 

 

14

10

12

11

15

 

 

 

13

10

14

 

 

 

 

12

10

ll

13

 

 

11

l

5
6
4

10

12

 

 

 

 

IV. Experimental Group - Left Hip Hyperextension

 

 

 

 

 

 

 

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r4

TRIAL

 

TRIG
R TH]

 

RTH2

RTH3

RTH4
LTH]

LTH2

LTH3
RLUM
LLUM

RGMAX

L GMAX

 

 

 

 

 

 

 

 

 

 

RHAM
LHAM

 

11

3

4
8

7

 

 

 

Sub'ect 203-Ex erimental

,_I

 

 

 

 

 

TRIAL

 

TRIG

 

R TH
L TH
R LUM
L LUM
R GMAX
L GMAX

 

 

 

 

 

 

RHAM
LHAM

 

 

 

65

 

 

 

20

 

 

19

 

 

18

 

 

17

 

16

 

 

 

15

 

 

14

 

 

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12

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Sub'ect 206-Ex erimental

r_.l

 

TRIA

 

TRIG

 

R TH
L TH
R LUM
L LUM
R GMAX
L GMAX

 

 

 

 

 

 

RHAM

LHAM

 

 

 

 

APPENDIX B

Median Muscle Firing Pattern

1. Control Group - Right Hip Hyperextension

R SIDE R HAM GMAX-1
101
102
103
104

5

106

108
100

dd‘Nd‘d‘d

11. Control Group - Left Hip Hyperextension

R L GMAXLLUMR 1R
3
7

 

 

67

III. Experimental Group - Median Muscle Firing Pattern For Right Hip
Hyperextension

R L

 

IV. Experimental Group - Median Muscle Firing Pattern For Left Hip
Hyperextension

L

 

 

APPENDIX C

Percent Occurrence Of Muscle Firing Patterns Based On Medians

1. Control Group - Right Hip Hyperextension

TRIG L R LOMAX R L
0 0 0 0 0
0 O 0
11% 22%

22% 33%
1 1% 33% 1 1%
0
44%
33%
1 1%

 

H. Control Group - Left Hip Hyperextension

SEQUENCE TRIGGER L R HAM L GMAX L LUM R LUM
1 1% O 0 0
89% 0 0
1 1% 33%
22%

 

68

69

III. Experimental Group - Right Hip Hyperextension

L HAM R L
0
0

OONOO‘UN-l

 

IV. Experimental Group - Left Hip Hyperextension

TRIG HAM R L R L LUM
0
83% 0
1 7%
0

 

 

 

APPENDIX D

 

 

DATA COLLECTION SHEET
Subject No.:
Date:
Name:
Group:
110.13.: Sex: Male______ Female_____

 

1. Have you ever injured your back? Yes__

2.Past surgical history:

No__

 

 

 

TEST

RESULT

 

 

 

 

Ll‘runk flexion

 

[Trunk extension

 

l Trunk S.B.-right

Trunk S.B.-|eft

 

True leg length

 

 

h.—

 

EPParent leg length

 

\ Hamstring flexibility
L‘

 

MM. Thomas Test
R

 

Hams/Erector spinae lenstll

 

 

 

 

7O

 

 

APPENDIX E

WRITTEN INFORMED CONSENT STATEMENT

Subject's Name:

 

I have freely consented to take part in a scientific study entitled, "Muscle Movement Patterns of the
Selected Extensor‘s During Prone Hip Hyperextension." This research study is designed to measure
movement patterns of the hamstrings, gluteus maximus, and lumbar erector Spinae. The database will include
individuals with back/spinal disorders, and individuals without back/spinal disorders. All of the tests will be
conducted in the Clinical Center-Dept. of Rehabilitation Medicine and no invasive measurement techniques
will be used.

If I am apprehensive about lying on my stomach and performing leg lifts I will withdraw from taking part in
that activity and also understand that I am free to withdraw from this study at any time without penalty.
Additionally, no permanent identifiable photographic data will be retained without my permission. I
understand all results will be treated with strict confidence, and I will remain anonymous. On request and
within these restrictions, results will be made available to me upon my request.

I understand that in the unlikely event of injury resulting from research procedures, Michigan State
University, its agents, and employees will assume that responsibility as required by law. Emergency medical
treatment for injuries or illness is available where the injury or illness is incurred in the course of an
experiment. I have been advised that I should look toward my own health insurance program for payment of
said medical expenses.

Date: Signed:
Address:

 

 

 

 

Telephone number:

 

 

Witness:

Principal Investigator: J. Nelson P.T. Advisor: D. Ulibarri, PhD.
A114 Clinical Center 101 I.M. Circle
Dept. P.M.R. 355-7648 355-4733

71

 

APPENDIX F

McGill Short-Form Pain Questionnaire

Patient’s Name

 

 

 

 

 

 

 

NONE MILD MODERATE SEVERE
THROBBING l) 2) 3)
SHOOTING l) 2) 3)
STABBING 1) 2) 3)
SHARP 1) 2) 3)
CRAMPING l) 2) 3)
GNAWING 1) 2) 3)
HOT-BURNING l) 2) 3)
ACHING 1) 2) 3)
HEAVY 1) 2) 3)
TENDER l) 2) 3)
SPLITTING 1) 2) 3)
TIRING-EXHAUSTING 1) 2) 3)
SICKENING 1) 2) 3)
FEARFUL l) 2) 3)
PUNISHING-CRUEL l) 2) 3)
PP]:
O NO PAIN
1 MILD
2 DISCOMFORTING
3 DISTRESSING
4 HORRIBLE NO PAIN WORST
POSSIBLE
5 EXCRUCIATING PAIN

 

Reprinted with permission. Melzack R. The Short-Form McGill Pain Questionnaire. Pain 1987; 30:191-197.

72

APPENDIX G

DEFINITIONS

1. Active Trunk Flexion: The subject was standing tall. Two inclinometers
were used to measure the motion. The interspace of T12-Ll and the sacrum
(center of posterior superior iliac spines) were marked using non-permanent
marker. One inclinometer was placed over the sacrum, while the other was g
placed over the T12-Ll interspace. The value of the T12-L1 measure

represented gross flexion. The value from the sacral inclinometer represented

hip flexion. The subject flexed forward and both inclinometers were read.

The value of true trunk flexion was determined by subtracting gross flexion

from hip flexion (Mayer, 1985).See Figure 4.

 

2. Active Trunk Extension: The inclinometers were set-up in the same
fashion as active trunk flexion, except the subject extended backward.
The value of true extension was determined by subtracting gross extension
(measured from T12-Ll interspace) from hip extension (measured from
sacrum) (Mayer, 1985). See Figure 4.

73

74

Figure 4. Trunk Flexion and Extension Using an Inclinometer

. I
11 5‘ Gross flexion {1:} '
\

-_69‘ Hip ftexlon /
55' Titre flexlon A

   

45' Gross extension
— 10' Hip extenSIon

,,I

 

   

 

 

 

Hamstrx .

/' 09 35‘ true extension 3

i

5‘

i

a

5

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Mayer, T. (1985). Using physical measurements to assess low back pain. Journal of‘ ‘ ' ' ' ' Medicine, 6, 44-59.

 

3. Active Trunk Sidebending: The inclinometers were set in the same fashion
as trunk flexion. The T12-L1 represented gross sidebending, and the sacral
inclinometer represented lateral pelvic bend. The subject was asked to
sidebend to one side, measurements were taken. The subject was then asked
to sidebend to the other side and measurements were taken. The true value of
active trunk sidebending was calculated by subtracting the gross sidebending
from the lateral pelvic sidebending (Mayer, 1985)

4. Modified Thomas Test: A test that can be used to measure the iliopsoas.
The subject was positioned supine with the legs placed at the edge of the
plinth. The leg not being assessed was held in flexion with the foot against
the examiner’s thigh. The leg being assessed is placed in extension at the hip,
and the knee is in 90°of flexion. This represented normal flexibility. A
positive test for tight iliopsoas was if the hip were at 15° of flexion at the hip.
(Kendall and McCreary, 1983).

5. Lumbar Erector Spinae Length: The subject was positioned in long sitting.
They were asked to touch their toes with their finger tips while keeping the
krree’s straight. This represented normal flexibility (Kendall and McCreary,
1983).

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6. Hamstring Flexibility: The subject was in a supine position. The
hamstrings group being assessed was flexed at the hip to 70°, while the other
leg was held down on the table. This represented normal flexibility (Kendall
and McCreary, 1983).

7. True Leg Length Measurement: Subject was in a supine position with legs
placed symmetrically. Using a tape measure, measure the distance from the
anterior superior iliac spines to the medial malleoli of the ankles
(Hoppenfeld, 1976).

8. Apparent Leg Length Measurement: Subject was placed in the supine
position with legs placed symmetrically. Using a tape measure, measure the
distance from the umbilicus to the medial malleolli of the ankles
(Hoppenfeld, 1976).

 

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