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THE EFFECTS OF PHYSICAL TRRIMNG ON 3M1“?
STRENGTH AND DYNAMIC WOR'i'i OF THE
GASTROCNEMIUS - PLANTARIS
MUSCLE GROUP IN MALE ALBINO RATS

Thesis for the Degree at M A
MECHEGAN STATE UNWERSITY
DONALD D. LUND
1988

11-16515

 

 

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THE EFFECTS OF PHYSICAL TRAINING ON STATIC STRENGTH
AND DYNAMIC WORK OF THE GASTROCNEMIUS—PLANTARIS

MUSCLE GROUP IN MALE ALBINO RATS

By

Donald D. Lund

AN ABSTRACT OF

A THESIS

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

MASTER OF ARTS

Department of Health, Physical Education
and Recreation

1968

ABSTRACT

THE EFFECTS OF PHYSICAL TRAINING ON STATIC
STRENGTH AND DYNAMIC WORK OF THE
GASTROCNEMIUS-PLANTARIS MUSCLE
GROUP IN MALE ALBINO RATS

by Donald D. Lund

An attempt was made to evaluate quantitatively the
static—strength and dynamic-work performances of the rat
gastrocnemius—plantaris muscle group.

Thirty-six adult male Sprague-Dawley rats were divided
randomly into training and control groups. All animals were
housed in sedentary cages, but the animals in the training
group were removed from their cages twice daily for two
periods of forced swimming. Each swimming period lasted
two hours. Each animal in the training group was forced
to swim with a weight of up to three per cent of its body
weight attached to its tail. This training program was
conducted five days a week for a period of six weeks.

At the end of the training program, each animal was
anesthetized with ether and the gastrochemius-plantaris
muscle group was exposed by clipping the achilles tendon.
The tendon then was attached to a strain gauge and stimu—
lated continuously for two seconds for an indication of

static-strength. The muscle then was attached to a

Donald D. Lund

one-hundred-gram weight while periodic stimulation was
applied for a ten—minute period. A linear variable dif-
ferential transformer recorded the total distance the
muscle lifted the weight for an indication of dynamic—
work.

It was found that there were no significant mean
differences in either static-strength or dynamic-work per-
formances measured in absolute terms. However, when the
performances were divided by body weight, it was found
that there were statistically significant mean differences
between the two groups. The trained animals had greater
relative static strengths and higher relative work outputs,
from the third through the tenth minutes of dynamic work,

than the control animals.

THE EFFECTS OF PHYSICAL TRAINING ON STATIC STRENGTH
AND DYNAMIC WORK OF THE GASTROCNEMIUS-PLANTARIS

MUSCLE GROUP IN MALE ALBINO RATS

.By

Donald D? Lund

A THESIS

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

MASTER OF ARTS
Department of Health, Physical Education

and Recreation

1968

DEDICATION

This thesis is respectfully dedicated to my parents,
John and Lorraine Lund, whose insight and sacrifice made

it possible for me to obtain my education.

11

ACKNOWLEDGMENTS

The author is indebted to Dr. William w. Heusner
for his guidance throughout my course of study; D. Edington
for his personal help and assistance; Robert L. Wells for
his work on the design and construction of the electrical
system of the apparatus; and D. Litwhiler, B. Sarnac and

R. Bowzer who gave willingly of their time and effort.

iii

Page

DEDICATION . . . . . . . . . . . . . . ii

ACKNOWLEDGMENTS . . . . . . . . . . . . iii

LIST OF TABLES . . . . . . . . . . . . Vi

LIST OF FIGURES . . . . . . . . . . . . Vii

LIST OF APPENDICES . . . . . . . . . . . viii

CHAPTER

I 0 INTRODUCTION 0 O O O O O O O O O O 1

Need for the Study . . . . . . . . 1

Purpose of the Study . . . . . . . 2

Scope of the Problem . . . . . . . 2

Subproblem . . . . . . . . . 3
Limitations of this Study . . . . . . 3-

Definition of Terms . . . . . . . . A

II. REVIEW OF RELATED LITERATURE . . . . . 5

III. EXPERIMENTAL METHOD . . . . . . . . 1“

Experimental Design . . . . . . . . 14

Training Routine . . . . . . . . . 15

Sacrifice Schedule . . . . . . . . 16

Measurement Procedure . . . . . . . 17

Statistical Procedure . . . . . . . 21

IV. RESULTS AND DISCUSSION . . . . . . . 23

Absolute Static Strength . . . . . . 23

Absolute Dynamic Work . . . . . . . 25

Body Weight . . . . . . . 25

Static Strength/Body Weight . . . . . 28

Dynamic Work/Body Weight . . . . . . 29

Discussion . . . . . . . . . . . 29

V. SUMMARY, CONCLUSIONS AND RECOMMENDATIONS . 3”

Summary . . . . . . . . . . . . 3“

Conclusions . . . . . . . . . . 36

Recommendations . . . . . . . . . 36

TABLE OF CONTENTS

iv

BIBLIOGRAPHY .

APPENDICES

Page
38
A1

Table

1.

LIST OF TABLES

Page
Analysis of Variance of Data for Absolute
Static Strength . . . . . . . . . . 23
Dynamic Work Performance of the Gastrocnemius
Plantaris Muscle Group in Gram-Centimeters. . 27

Analysis of Variance of Data on Body Weight . . 28

Analysis of Variance of Data of Static Strength
Divided by Body Weight . . . . . . . . 28

Dynamic Work Performance of the Gastrocnemius

Plantaris Muscle Group in Gram-Centimeters
Per Gram Body Weight . . . . . . .- . . 31

vi

Figure

la.

lb.

LIST OF FIGURES

Page

Animal Hooked up for Test of Static
Strength . . . . . . . . . 18
Animal Hooked up for Test of Dynamic Work . l8
Strain Gauge Hook-up . . . . . . . . 2O

Hook—up for Schavits Linear Variable
Differential Transformer . . . . . . 21
Static Strength . . . . . . . . 2“
Static Strength/Body Weight . . . . . . 24
Dynamic Work Performance . . . . . . . 26
Dynamic Work Performance/Body Weight . . . 3O

vii

LIST OF APPENDICES

Appendix Page
A. Trained . . . . . . . . “2
B. Non-Trained . . . . . . . . . . . . “3

C. One Way Analysis of Variance with the
Exercise Group as the Category Variable . . AA

viii

CHAPTER I

INTRODUCTION

Muscular performance has long been a subject of
research in physical education as well as in other areas
of science. It is a known fact that training produces
increases in muscle size, strength, and endurance (19).
Although this has become fundamental knowledge, the causes
behind these gross changes within the muscle still remain
open to detailed research.

In order to discover exactly what changes occur with
training, it has become necessary to go to the cellular,
-subcellular, and enzyme level to perform anatomical and
biochemical assays on trained and untrained muscles. Since
it is impossible to run these studies on human beings, the
research must be modified so as to be applicable to labora-
tory animals. By using animal studies, general principles
may be established relating to actual muscle changes. The
principles then may be applied to help understand muscular

performance in man.

Need for the Study

 

In humans it has been found that different types,

intensities and durations of physical training have various

effects on the muscular strength and endurance of the sub-
jects. Corresponding changes have been hypothesized, but
seldom observed, in animal training studies. With modern
techniques requiring extensive use of animals, there is
need for investigation to determine the specific effects
of various training programs on the muscular strength and
endurance of animals. The information gained from this
study should aid work which presently is being done on
muscle changes produced by training and should provide
insight as to the reasons for some of the histochemical,
anatomical and biochemical phenomena that have been ob-

served within the trained muscle.

Purpose of the Study

 

The purpose of this study was to measure the effects
of a program of endurance swimming on the rat gastrocnemius-
plantaris muscle group, according to its ability to perform
two well defined tests of muscular performance. These two
tests consisted of: (a) the measurement of static strength

and (b) the measurement of dynamic work.

Scope of the Problem

 

Forty-eight adult male laboratory rats were randomly
assigned to one of two groups. The control animals were
housed in sedentary cages with no outside activity. The
experimental group was housed in sedentary cages and removed

from their cages twice daily for two periods of forced

swimming. The training program was conducted five days
a week for a period of six weeks.

At the conclusion of the training period, each
animal was anesthetized with ether, and the gatrocnemius-
plantaris muscle group was exposed by surgically freeing
the achilles tendon. The tendon then was attached to a
muscle performance analyzer. The muscle was stimulated
and measurements of static strength and dynamic work were

taken.

Subproblem

 

Since there was no readily available apparatus for
the measurement of static strength and dynamic work in
the rat, an instrument was developed for this purpose.
That instrument has been called a "Muscle Performance

Analyzer" and is described in Chapter III.

Limitations of this Study

 

1. Method of training: Swimming as a method of training
gave no way to quantitatively measure the total work
which was being done by each animal during each train-
ing session.

2. Size of sample: Due to the laboratory conditions,
the number of animals was limited to forty—eight.

3. Span of time: Training the animals for six weeks may
not have been a sufficient length of time to establish
maximal performance changes in the muscle groups

studied.

Type of exercise: In the current study, the forced
swimming was a different type of exercise in both
intensity and duration than either the static—strength
or dynamic-work tests. These tests may not have been
accurate measurements of the changes that occurred

within the training program.

Definition of Terms
Static Strength: A maximal contraction of the muscle
group against an immovable resistance.
Dynamic Work: A muscular contraction in which a
given resistance is moved a given distance as the

muscle contracts.

CHAPTER II

REVIEW OF RELATED LITERATURE

It is beyond the scope of this paper to report on
all of the different studies pertaining to muscular per—
formance. This paper will be limited, therefore, to
pertinent works concerning animal research such as the
study upon which this thesis is based.

HypertrOphy within muscle fibers, as the result of
athletic training, has been an accepted fact for many years.
Morpurgo, (12), in his classic anatomical study during 1897,
was the first to show the effects of training on hypertrOphy
of muscles. In his study, the satorious muscle was removed
from one leg of a dog. After removal of the muscle, the dog
was trained strenuously through running. Upon completion of
the training period, Morpurgo removed the satorious muscle
from the dog's other leg and compared it to the first muscle.
He found an increase in muscle-mass which was due entirely
to an increase of sarcoplasm within the individual muscle
fibers. There was no change in the number of muscle fibers,
the fiber length, the number of nuclei, or the number or
size of the muscle fibrillae.

A study similar to Morpurgo's was conducted by Siebert

(17) in which the results of Morpurgo's study were

substantiated. Siebert also found further indications re-
lating to the great importance of the type of training used.
As part of the study there was stimulation of both legs of a
frog for a period of twenty minutes each day. One leg of
the frog was found to contract isotonically, while the other
was forced to contract isometrically. After fourteen days
of this type of training, it was found that the leg con-
tracting isometrically was thirteen per cent heavier than
the leg which was trained with isotonic contractions.

Steinhaus (l9) cited Siebert as stating that the ex-
tent of hypertrophy of a muscle is related to the speed of
running rather than to the duration of the running period.

By examining the gastrocnemius of running rats, Siebert
found that those who had run at a moderate speed had only
slight hypertrophy and that this degree of hypertrophy was
independent of the distance the animal was forced to run.
In order to obtain increased hypertrophy within the muscle,
it was necessary to make the animal run at a greater Speed.
It was concluded that the extent of hypertrOphy is a func-
tion of the amount of work performed in a given unit of
time.

Gordon, Kowalski and Fritts (7) found that changes with-
in the muscle depend upon the type of training that is uti-
lized. A repetitive low-force type of training, such as run-
ning, when applied to rats produces a trend toward an increase

in the concentration of sarcoplasmic proteins. Following

forceful activities, such as weight-lifting, there

tends to be an increase in the concentration of acto-
myosin within the muscle fibers. This indicates that
training does not cause a general change within the mus-
cle. The type of change is dependent upon the type of
training.

Until 1961, hypertrophy of the muscle was attri-
buted to an increase in the volume of the muscle fibers.
In 1962, Van Linge (21) reported changes on the plantaris
muscle caused by heavy training. The triceps surae mus-
cle of the hind limb of a rat was denervated. Then the
tendon of the plantaris muscle was implanted onto the
tuberosity of the calcaneus. This was done so that the
work of the triceps surae would be assumed by the plan-
taris. The weight of the plantaris is normally only
eighteen per cent that of the triceps surae. The animals
then were forced to run up a twenty-seven degree incline
for nine hours a day. This was done for a period of
thirty days.

The changes Van Linge noted were astonishing. It
was found that the plantaris could take the place of the
triceps surae, a muscle group which is normally over five
times its Size. The plantaris had almost doubled its
weight and had tripled its force of contraction. Along
with an increase in sarcoplasmic material, Van Linge
also noted indirect evidence of hyperplasia, the formation

of new muscle fibers within the experimental muscle.

 

 

 

Increases in muscle strength do not necessarily accom—
pany muscle hypertrophy. Bigland and Jehring (2) injected
full grown rats with a growth hormone over a twenty-one day
period. Upon completion of the test period, the injected
animals were found to be heavier than the controls by twenty
per cent. Also, cross sections of the muscles revealed a six
to twelve per cent increase in area of the experimental group
over the control group. However, isometric records taken
of single twitches, summated twitches, tetanus, and fatigue
showed that the treated animal's muscles produced less ten-
sion per gram of muscle weight than did those of the control
group.

An increase in strength does not always cause a
noticeable hypertrophy within the muscle. A study car-
ried out by Goldspink (6) showed that muscle weight, and
consequently muscle girth, are unreliable indices of
hypertrophy. In young mice exercised by weight lifting,
Goldspink found no change in the weight of the muscle;
but upon examination of the fibers, he found an increase
of about thirty per cent in the mean cross—sectional area.
He concluded that the muscle fiber growth came about at
the expense of the extra-cellular tissue.

Schwarts (18) performed a study in which she measured
the gastrocnemius and soleus muscle weight, length, water
and nitrogen content, active and passive length-tension

curves, and twitch and tetanic-tension responses in

\0

growing male rats between the ages of twenty-four and
one-hundred and thirty-one days. She found that the mus-
cle weight was an increasing proportion of the body
weight of the animal, whereas the muscle length increased
at a declining rate, as the animal aged. Water con-
stituted a decreasing, and nitrogen an increasing, pro-
portion of muscle weight as the animal aged. The length-
tension relationship was unchanged over the measured

Span of time. Contraction strength to wet muscle weight
was a constant ratio throughout the age range. However,
the ratios of contraction strength to dry weight or to
nitrogen content were higher in the younger rats than in
the older rats.

Often the mechanical advantage of muscles acting
together can make a difference in performance. Thompson
(20) investigated how the responses of the separate heads
of the rat gastrocnemius muscle were related to the
response of the whole muscle. By using isometric twitch-
tension contractions he found that the response of the
lateral head was forty—six and three-tenths per cent
greater than the response of the medial head. Comparing
the summation of the responses of these two separate
heads to the response of the whole muscle, he found that
this summation was within four and six-tenths per cent
of the response of the whole muscle. When using iso-

metric tetanus-tension contractions of the medial and

lO

lateral heads there was found to be little if any differ-
ence between the heads. However, when these individual
tetanus-tension responses were added together, the value
was only sixty-eight per cent of the value of the response
of the whole muscle. In summary, he showed that the ten-
sions of the two halves of the muscle did not equal the
total tension of the whole muscle, for something was lost
in the separation. Thompson attributed this loss to a
decrease in mechanical advantage brought about by the
muscle being separated.

In measuring muscle contractions of animals, it
must be remembered that a true isometric or isotonic con-
traction rarely occurs in the body (1). That is, labora—
tory tests of animals are highly artificial, and at their
best will give only partial information concerning the
animals' true capacity for muscular performance.

In 196A CouttS (A) introduced a method for con-
trolled muscular exercise in anethetized laboratory rats
without removing the muscle. This method involves im-
plantation of permanent electrodes around the tibial
nerve. The advantage of this method is the ability to
take intermittent measurements during exercise-bouts
throughout the study, rather than Just a single measure
of muscle work output upon sacrifice of the animal. At
the same time, this method of exercise allows for greater

specification of work—output within the experimental

11

group. In order for this method to be successful, how-
ever, the techniques of anethetization and electrode
implantation need further investigation and perfection.

The methods of measuring static contractions have
varied according to the methods used for muscle stimula-
tion. In studies using a single twitch, the muscle was
stimulated by one electrical impulse which caused the
muscle to contract. Following contraction, complete
relaxation took place (ll, l3, 18, 20). A muscle stim—
ulated in this manner forms a bell—shaped tension curve.

In one study, the muscle was stimulated by using
a summated twitch, in which a second stimulus was applied
before the muscle had time to relax from the first stim-
ulus (2). This caused the muscle to contract again
before complete relaxation occurred. Individual responses
could be seen in the contraction.

In other studies, the rate of stimulation was
increased even more so that the responses became com-
pletely fused. When the contraction curve is completely
fused it is called a tetanic contraction. This is the
method that has been used most often in tests for static
contractions (2, 10, 16, 18, 20).

For dynamic-work performance, stimulations have
been applied to the muscle so it could move a given
resistance a number of times in single twitches. An

early attempt of this type was made by Heron, Hales, and

12

Ingles (8) when they tried to determine the capacity of the
rat gastrocnemius muscle group to maintain work output.

The tibias of ten rats were exposed, and a one-hundred—gram
weight was attached by a linen thread to the freed tendon
of each gastrocnemius. The muscle then was stimulated
directly at the rate of three times per second. Upon
stimulation, the muscle lifted the weight by means of the
attached thread which was looped around a pully. The pully
was attached to an apparatus which activated a veeder coun-
ter and measured the total distance the weight had been
moved. From this measurement, the work output could be
expressed in kilogram-meters for each twenty-four hour
period.

The experimenters found that continuous muscle con—
tractions were in one case carried out over a seventeen-
day period, after which the muscle still was contracting
at thirty per cent of the initial work rate. It also was
noted that work output does not always decrease at a uni-
form rate. In some cases, the animals were capable of out
performing their own activity record from the preceding
day.

In 19AM Ingle (9) replaced this original apparatus
with a compact one—way clutch within the pully, which was
attached directly to the veeder counter. When the muscle
contracted, the weighted cord around the pully moved,
giving a direct read—out of the work done on the veeder

counter.

13

From these aforementioned studies, it can be seen
that most of the problems relating to changes within the
muscle are still unanswered or open to controversy. A
great deal of extensive research still needs to be done to
determine the causes of muscle changes brought about by
training. To do this effectively, the researcher must
first qualify his measurements so he may identify and

objectively define a trained muscle.

CHAPTER III

EXPERIMENTAL METHOD

Experimental Design

 

One-hundred-five male, weanling (twenty-three day
old), Sprague—Dawley rats were brought into the labora—
tory and housed in individual voluntary activity cages
for five days. The cages housing these rats were 18 x 18 x
2A centimeters, with an activity wheel 12.5 centimeters
wide, and 35 centimeters in diameter.

The animals were allowed two days of adjustment to
their new laboratory environment, after which spontaneous
activity records of total revolutions run in the activity
wheels were kept for three days. In order to obtain a
homogeneous sample, those animals with the highest and
lowest activity levels were eliminated from the study.

Forty—eight animals in the central activity range
for the three day period, were selected for the study.
These then were ranked according to revolutions run during
the aforementioned three-day period. After being ranked,
the animals were systematically assigned into one of two
groups. This assignment consisted of putting the first
animal into group A, the second and third animals into

group B, the fourth and fifth animals into group A, the

1A

15

sixth and seventh animals into group B, etc. By using
this method, any bias from assigning the animals into
groups was eliminated. A flip of a coin was the deter-
mining factor deciding which group would receive the
experimental procedure.

Once the groups were determined, the animals were
transferred into 18 x 18 x 2A—centimeter sedentary cages.
The activity of the sedentary animals was further curtailed
by inserting a piece of sheet metal from the upper left
corner of the cage to the lower right corner, which cut
the total volume of the cage in half. All forty—eight
cages were held on a rack, with twenty-four cages on each
side. The rack was divided into four levels housing six
animals on each row. The cages for the experimental and
control animals were alternated on the rack so there were
three animals from each group on every row.

The lighting in the room where the animals were
housed was in cycles of twelve hours of light and twelve
hours of darkness. The temperature was held at twenty-
five degrees centigrade with a variation allowance of plus
or minus one degree. All of the animals were fed "Wayne

Lab Blox" ad libitum and given free access to water. The

 

body weight of each animal was taken and recorded on Thurs-

day of each week.

Training_Routine

 

The experimental group was removed from their cages

twice daily (from three to five P.M. and from nine to

l6

eleven P.M.) Monday through Friday each week, for forced
swimming sessions. The animals were then placed into
especially constructed individual cylinders, twenty—five
centimeters in diameter and one and two-tenths meters
deep, so as to eliminate any interference with other
animals. Throughout this period the water temperature was
maintained at thirty to thirty-two degrees centigrade.

During the first week of training, the experimental
animals swam without any extra weight so as to allow for
adjustment to swimming in the tanks. During the second
week, each animal was made to carry a weight which con—
sisted of two per cent of his body weight. The extra
weight was added to the end of the animals tail by means
of a plastic clothes pin. For the third and all subse-
quent weeks, the extra weight was maintained at three per
cent of the animals body weight which was determined the
Thursday before. These weights were accurate to a plus
(or minus) ten milligrams.

Upon termination of each swim, the weights were
removed and the animals were individually dried with towels

and then returned to their cages.

Sacrifice Schedule

 

At the completion of the experimental period, eighteen
animals from each group were randomly selected by use of
a table of random numbers. The order in which the animals

were randomly selected Served as the sacrifice schedule.

17

Three animals were sacrificed from each group, each day,
for a total of six days. All of the experimental animals
went through their daily training schedule until the day

before they were sacrificed.

Measurement Procedure

 

The measurement procedure consisted of anesthetizing
the animals by use of an anesthetic chamber containing
ether. Once the animal was lightly anesthetized, he was
maintained in this state by administration of additional
ether through a nose cone.

A sample of blood for a pre-exercise lactic acid
analysis was taken from each animal. The femoral vein
was exposed and one milliliter of blood was extracted.

The data obtained from this analysis is reported in another
study (14). The gastrocnemius—plantaris and soleus muscle
group of the left hind leg then was freed surgically by
clipping the Achilles tendon. The soleus muscle of that
leg was removed for histochemical analysis which was part
of another study (3). The animal then was placed on his
back and attached to the "muscle performance analyzer"
(see Figures la and lb). In this position, the proximal
end of the muscle group was held in a fixed position by

a hemostat which was attached to the apparatus. The dis—
tal end (the Achilles tendon) was attached by an alligator
clip to a nylon filament which could be attached to either

a static or dynamic recording unit.

l8

Strain Gauge mounted
on spring
steel-———+

 

 

 

 

 

 

 

 

 

Figure la.--Animal hooked up for test of static
strength.

Linear variable differential {A
transformer

FY—

 

 

 

 

 

g

 

 

 

 

 

 

 

 

 

 

 

Figure lb.--Animal hooked up for test of dynamic work.

19

With the anesthetized animal on the apparatus, the
gastrocnemiusfplantaris muscles group was stimulated
directly. The hemostat holding the leg served as the
anode and the clip attached to the Achilles tendon was
used for the cathode. To stimulate the muscle, a twenty-
volt square wave impulse from a Grass Model Se“ stimulator
was used with a ten-thousand ohm resister in the circuit.
This made the current across the muscle approximately two
milliamperes. By using this large voltage with a high
resistance in the circuit, any additional resistance that
might occur from the electrodes or the muscle itself would
not affect the experiment. I

The measurement of static—strength was made by the
use of a strain gauge mounted on a piece of spring steel
which was attached to the nylon filament from the muscle.
The muscle was stimulated for two seconds, and this stim—
ulation was repeated a total of three times. The strain
gauge acted as a variable resister, giving a linear output
on a Gilson recorder for the static contraction from the
muscle. A second strain gauge was used to provide a con-
stant reading for variations in temperature and humidity
that might occur in the laboratory during the course of
the experiment.

For measurement of the dynamic-work capacity of the
muscle, the nylon monofilament was attached to a one—

hundred-gram weight. Stimulation was applied to the muscle

 

 

 

 

 

 

 

><+> Gilson
\\E\\P 1200 Recorder
E; Input (Chopper)
120“ >} Strain
SR-A Gauge In-
SR-A St .~ G ,0? t
Strain rain adb" .gGround pu

Gauge (Reference)

Figure 2.--Strain Gauge hook-up.

twice a second for a total of ten minutes. To find the
total distance that the weight was lifted, the filament
was attached to a bar which passed through a linear vari-
able differential transformer. The linear variable dif—
ferential transformer consists primarily of three coils
interwound with a sixty cycle A.C. current running through
them. As the bar is displaced from the center it causes
the current to vary. This current is changed into a D.C.
output which can be recorded on a Gilson recorder (see
Figure 3).

With the instruments calibrated, measurements of the
deflections could be taken with calipers directly from the
Gilson paper and then converted to actual values. These
values were the actual work done by each animal.

After the exercise routine was completed, a second
blood sample was obtained from the femoral vein for a
post-exercise lactic acid analysis. This sample was com-

pared to the pre—exercise sample, and the results are

?1

 

 

 

 

 

 

 

 

 

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Gilson Recorder

Figure 3.--Hook—up.for Schavits linear (Chopper Channel)

variable differential trans-
former.

reported in another study (1U). Lastly, the muscle, heart,
and the liver of each animal were frozen and used for bio—

chemical assays which are reported in another study (5).

Statistical Procedure

 

Statistical calculations were done using the UNEQl
routine for one-way analyses of variance, and the BASTAT
routine for the correlation analyses. All work was done
using Michigan State University's Control Data 3600
Computer.

The null hypothesis tested was (Ml - M2 i 0). Alpha
was set at 0.05 while bata was set at the .20 level. It
was decided that any mean difference between groups as
large as or larger than one-half of one standard deviation
was biologically important and should be detected as sig-
nificant. With these specifications, a sample of sixty-
three animals per group was necessary and sufficient.
Since the groups nl = n2 = 18 the following critical

regions were established.

22

F > 4.12: Reject H at the ninety-five per cent
level of confidence.

F < 1.53: Accept H0 at the eighty per cent level
of confidence.

“.12 :pF 3 1.53: Reserve judgement.

CHAPTER IV
RESULTS AND DISCUSSION

This experiment was undertaken to determine the
effects of a low-intensity high—duration training program
on the static-strength and dynamic—work performance of
the rat's gastrocnemius-plantaris muscle group. It was
hypothesized that the experimental group would out-perform
the control group in both static-strength and dynamic-work
output. This data will be useful in other studies per-
taining to this experiment (3,5,14). The correlations
between pyridine nucleotides, blood lactic acid, and

performance may be found in Edington (5).

Absolute Static Strength
Statistically, there were no significant differences
between the groups in absolute static strength. The

results of this analysis are presented in Table 1.

TABLE l.—-Analysis of variance of data for absolute static

 

 

strength.
Degrees
Souooe $332.21.: of 1 524322.. FEES“
Freedom '
Among GPOUPS 5775.99 1 577.99 0 77 0 38
Within Groups 252909.22« 3A 7A38.50 ° °
Total 258685.22 35

 

23

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body weight.

Figure Ab.-—Static strength/

Figure Aa.-—Static strength.

25

The static-strength means and standard deviations for the
trained and untrained groups are presented in Figure 4a.

The raw data may be found in Appendices A and B.

Absolute Dynamic Work

 

The analysis of variance did not detect a signifi-

cant difference in total mean dynamic work between the

H-

trained animals (2645.4 142.5 grams—cms.) and the un-
trained animals (2715.4 i 145.5 grams—cms.). However,

when the total work is broken down into individual minutes
it can be seen that the untrained animals performed Signi-
ficantly more work during the first minute than the untrained.
These results may be found in Table 2 and in Figure 5.

The values and the probability levels are recorded in

Appendix C.

Body Weight

 

The mean difference in final body weight was sta-
tistically significant (p < .0005). At the end of the
study the exercised animals weighed an average of 264
grams per animal, while the controls weighed an average
of 328 grams each. These results may be seen in Table
3.

Sarville and Smith (15) found that the weight of
the muscle in the hind limb is highly correlated (r = .96)
with the body weight of the animal. Since this is the

case, dividing static-strength or dynamic—work performance

Gram CMS.

600 ‘

400

300

i.

26

L \ Work vs. Time

T
’

 

Trained

—-—- Non-Trained

 

: : u e e .1
1 2 3 u 5 6 7

Minutes
Figure 5.--Dynamic work performance.

 

27

TABLE 2.--Dynamic-work performance of the Gastrocnemius-

 

j

plantaris muscle group in Gram-Centimeters.

 

 

_ —'w

 

Variable Trained Non-Trained

One* 570.61 i 22.76 677.58 : 15.89
Two 421.71 1 20.87 467.98 i 19.40
Three 304.60 i 19.12 320.62 i 18.77
Four 250.65 1 17.42 241.32 : 17.33
Five 211.98 i 16.77 200.79 i 17.51
Six 198.32 i 13.68 189.35 i 19.83
Seven 189.35 i 13.33 171.05 : 16.23
Eight 175.39 i 13.67 159.03 i 16.67
Nine 165.89 i 13.66 147.30 i 15.41
Ten 156.89 i 13.05 140.33 i 16.00

 

28

TABLE 3.—-Analysis of variance of data on body weight.

 

 

Sum of Degrees of Mean Sign. of
Source Squares Freedom Squares F F Stat.
Among Groups 36608.44 1 36608.44
52.50 0.0005
Within Groups 23704.44 34 697.18
Total 60312.88 35

 

by body weight would give a good indication of performance
per gram of muscle weight of the animal. This method
might provide a better indication of the actual performance

of the animal than the absolute strength or values.

Static-Strength/Body Weight

 

When static strength was divided by body weight,
it was found that the exercised animals had more relative
strength than the sedentary group (p = 0.001). The
results may be seen in Figure 4b. The analysis of vari-
ance may be seen in Table 4.

TABLE 4.--Analysis of variance of data of static—strength
divided by body weight.

 

 

Sum of Degrees of Mean Sign. of
Source Squares Freedom Squares F F Stat.
Among Groups 1.43 l 1.42
12.66 0.001
Within Groups 3.83 34 0.11

Total 5.26 35

 

29

Dynamic Work/Body Weight

 

The results of dynamic work divided by body weight
have been summarized in Figure 6. In analyzing the data
by individual minutes, it was found that there was no sig-
nificant difference between the groups during the first
minute. The value of the F—stastic obtained for the second
minute was in the reserve-judgement region. This value
may be found in Appendix C. During the third through the
tenth minutes, it was found that the trained animals Sig-
nificantly (p = 0.05) out—performed the untrained animals
in relative dynamic work. The results may be Seen in
Table 5. The F values and the probability levels may be

found in Appendix C.

Discussion

 

As was reported earlier, the type of training is
important when specific changes are sought within the
body. In order for training of any type to occur, stress
has to be placed upon the body. In this study, the ani—
mals were stressed through forced swimming. They swam
two periods of two hours each, five days a week. During
the swimming exercise, each animal had a weight of up to
three per cent of its body weight attached to its tail.
This was a low—intensity, high—duration type of training.

In evaluating muscle performance, a static contrac—
tion of the muscle was used as one test. This type of

test was based upon the total strength of the muscle and

Gram CM/Gram Body Weight.

30

Gram CM/Gram Body Weight.

A ———— Trained

-- Non-Trained

 

 

. \ It Significant

(p < .05)

105.0.

1.04;

0
U1
If

 

Minutes

Figure 6.--Dynamic work performance/body weight.

 

 

TABLE 5 —-Dynamic—work performance of the gastrocnemius~
plantaris muscle group in Gram-Centimeters per-

 

gram-body-weight.

 

 

Variable Trained Non—Trained
One/Wt. 2.15 i .061 2.06 i .047
Two/Wt. 1.58 t .058 1.42 i .056
Three/Wt. 1.14 i .063 0.97 t .053
Four/Wt. 0.94 i .062 0.73 i .047
Five/Wt. 0.79 i .060 0.60 i .049
Six/Wt. 0.75 t .052 0.57 i .059
Seven/Wt. 0.72 i .052 0.51 i .047
Eight/Wt. 0.66 i .053 0.48 i .049
Nine/Wt. 0.62 i .051 0.44 i .046

H-

Ten/Wt. 0.59 .046 0.42 i .049

 

was not necessarily related to the type of training program
employed. Thus, this test would be best suited for evalua-
ting the effects of a high-intensity, low—duration type of
training program such as weight lifting. It was not well
suited to the forced-swimming training program that was
used.

The second test was for dynamic work in which the
muscle lifted a one—hundred-gram weight twice a second for
ten minutes. Although this test was better suited to the
type of training that was used, it still may not have been
ideal. The work rate of lifting a one—hundred-gram weight
twice a second was relatively high as compared to the
forced-swimming program. Also, the period of time may
have been too short to give the trained animals a chance
to demonstrate the full effects of this type of training.
If the testing had been carried out over a period of two
hours, such as was used in the training program, the
trained animals might have been able to out-perform the
sedentary group even more.

Another factor affecting muscle performance could
have been the stimulation of the muscle. The muscle was
stimulated directly, causing all of the muscle fibers to
contract at once. In training, certain patterns are set
up in which only specific fibers contract for optimum
muscle performance. These patterns are controlled by

motor units which fire in a given order. By stimulating

33

all of the muscle fibers at once, this training effect
may have been lost.

Another difficulty encountered was that the stress
applied during the training was large enough to produce
a significant difference between groups in body weight.
This variation of body weights between groups could have
made a big difference in the performances of the animals.
In sporting events such as wrestling, boxing, judo and
weight lifting, the contestants are matched according to
body weight. If the muscles in the hind limb of the rat
are related to body weight as Sarville and Smith (15)
suggested, then the trained group was at a disadvantage
in the tests of absolute performance. The tests of relative

performance probably were much more valid.

CHAPTER V

SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

Summary

The purpose of this study was to determine the
effects of forced—swimming training on the gastrocnemius-
plantaris muscle group through static-strength and dynamic—
work tests.

Two groups, each consisting of eighteen young male
albino (Sprague-Dawley) rats, were randomly assigned to
training and control groups. All of the animals were
housed in standard 18 x 18 x 24 centimeter sedentary
cages. The controls had their activity further curtailed
by bisecting the volume of the cages.

The training group was removed from their cages
twice daily, once from three to five P.M. and again from
nine to eleven P.M. for four hours of forced swimming
daily. Each animal swam with a weight of up to three per
cent of its body weight attached to its tail. This pro-
gram was carried on five days a week for a period of six
weeks.

At the end of the training period, each animal was
anesthetized lightly with ether and the left femoral vein

was exposed. One milliliter of blood was removed for a

34

35

blood lactic acid analysis. The gastrocnemius-plantaris-
Soleus muscle group of the left hind leg was surgically
.freed by clipping the Achilles tendon. The soleus muscle
was removed for a parallel histochemical study. The ten-
don was attached to a nylon monofilament which was attached
to a spring steel plate. A strain gauge on the steel

plate was used to measure static strength. The muscle was
stimulated directly for two seconds using a supermaximal
square—wave impulse from a Grass Model S4 stimulator.

The filament from the muscle then was attached to
a one-hundred—gram weight and the muscle was stimulated
twice a second for a total of ten minutes. The filament
attached to the weight passed through a linear variable
differential transformer which recorded the total dynamic~
work output of the muscle.

At the end of the stimulation phase, one milliliter
of blood was extracted from the left femoral vein and
used for a post exercise blood lactic acid analysis.
Finally, the heart, the liver, and the muscle were quick-
frozen for use in biochemical assays of pyridine
nucleotides.

The lactic acid and pyridine-nucleotide results are

reported in other studies (5, 14).

Conclusions

 

l. The training routine of forced swimming signifi-
cantly reduced the body weight of the experimental animals

as compared to the controls.

36

2. There were no significant differences between
groups either in absolute static strength or in absolute
dynamic work performance.

3. When static strength was divided by body weight,
the trained animals were found to have significantly
greater relative strength.

4. The trained group significantly out—performed
the sedentary control group in dynamic work divided by
body weight during the third through the tenth minutes

of the dynamic-work test.

Recommendations

 

l. The experimental procedure should be repeated
under conditions designed to equalize the mean body weights
of the two groups of animals.

2. In future studies, the muscle weights and the
fiber sizes should be established at the conclusion of
the study.

3. Training routines other than forced swimming
should be studied under the same experimental design.

4. Studies using varying intensities and durations
of training programs should be conducted.

5. Similar studies should be conducted using dif-
ferent time intervals to determine the optimum period
of training.

6. Attempts should be made to control the tempera-

ture of the muscle during the testing of work performance.

37

.1

7. Several anesthetics including ether, should be
studied to determine what effects they may have on work

performance.

BIBLIOGRAPHY

38

10.

11.

BIBLIOGRAPHY

Asmussen, Erling. Muscular performance. In Rodahl
and Harvath (ed.), Muscle as a tissue. New York:
McGraw Hill Book Company, Inc., 1960.

 

Bigland, B. and Jahring, B. Muscle performance in
rats, normal and treated with growth hormone. Jour—
nal of Physiol., 116:129, 1952.

 

Bowzer, R. Unpublished Masters Thesis. Michigan
State University, 1968.

Coutts, K. D. A method for the controlled muscular
exercise of laboratory rats. Unpublished Masters
Thesis, Michigan State University, 1964.

 

 

Edington, D. W. Pyridine nucleotide concentrations
and ratios in rat muscle, heart, and liver in response

 

 

to acute and chronic exercise. Unpublished Doctoral
Dissertation, Michigan State University, 1968.

 

Goldspint, G. The combined effects of exercise and re—
duced food intakes of Skeletal muscle fibers. J;
Cell. Comp. Physiol., 63:209, 1964.

 

Gordon, E. E., Kowalski, K., and Fritts, M. Adapta-
tions of muscle to various exercise. J. Am. Med.
Assoc., ll9:103, 1967.

 

Heron, W. T., Hales, W. ,. and Ingle, D. J. Capacity
of skeletal muscle in rats to maintain work output.
Amer. J. of Physiol., 110:357, 1934.

 

Ingle, D. J. Quantitative assay of adrenal cortical
hormones by muscle work tests in adrenalectomized
nephrectomized rats. Endocrine, 34:191, 1944.

 

Knowlton, G. C. and Hines, H. M. The effect of growth
and atrophy upon the strength of skeletal muscles.
Amer. J. of Phy., 128:521, 1940.

 

Lock, Simon. Response of motor unit of gastrocnemius
of the rat to repetitive stimulus. Amer. J. of
Physigl., 203:461, 1962.

 

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

40

Morpurgo, B. Activitats—hypertrophie der willkur—
lichen muskeln. Arch. Path. Anat. 150 (pt. 3):
522, 1897.

 

Sandon, A. and Burst, M. Contractability of dystro-
phic mouse muscle. Amer. J. of Physiol., 194:577,
1958.

Saranac, B. Unpublished Masters Thesis. Michigan
State University, 1968.

Saville, P.D. and Smith, R. Bone density, breaking
force and leg muscle mass as functions of weight in
bipedal rats. Amer. J. Phys. Anth., 25:35, 1967.

 

Schottelius, B. A. and Schottelius, D. D. Force
velocity of vitamin E deficient skeletal muscle.
Amer. J. of Physiol., 1932219, 1958.

 

Siebert, Werner. Investigation of hypertrophy of
skeletal muscle. Zschr. Klin. Med., 109:350, 1928.
Translated by Robert Kramer. J. of Ass. for Phys-
ical and Mental Rehab., 14:153. 1960.

 

 

 

Schwartz, Neena B. Changing size, composition and
contraction strength of the gastrocnemius muscle.
Amer. J. of Phy., 201(1):l64, 1961.

 

Steinhaus, A. H. Chronic effects of exercise. Phy-
siol. Rev., 13:103, 1933.

 

Thompson, J. D. Dimensional and dynamic features of
mammalian gastrocnemius muscle. Amer- J. of Physiol.
200:951, 1961.

Van Linge, B. The response of muscle to strenuous
exercise. J. Bone and Joint Surgery., 44-Bz7ll,

1962.

 

APPENDICES

41.

.42

 

 

 

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43

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44

APPENDIX C.--One way analysis of variance with the exercise
group as the category variable.

 

 

 

 

 

Dynamic Work

 

QZEEESigt F-Statistic Probability
One 14.84 0.0005*
Two 2.63 0.114
Three 0.35 0.554
Four 0.14 0.707
Five 0.21 0.648
Six 0.13 0.712
Seven 0.75 0.390
Eight 0.57 0.453
Nine 0.81 0.373
Ten 0.64 0.428
One/Wt 1.22 0.275
Two/Wt 3.98 0.054
Three/Wt 4.41 0.043*
Four/Wt 7.60 0.009*
Five/Wt 6.13 0.018*
Six/Wt 5.10 0.030*
Seven/Wt 8.10 0.007*
Eight/Wt 6.31 0.017*
Nine/Wt 6.77 0.014*
Ten/Wt 5.76 0.022*

 

*Statistically significant at < 0.05 level.