Effect of Static ma?

Dyndmic Exercises on
Mmcdm Strength and Hypertrophyl
PHILIP J. RASCH AND LAURENCE E. MOREHOUSE. Frown tlze Research
Center, College of Osteopathic Physicians and Surgeons, and Los Angeles County
Osteopatlk Hospital, Los Angeles, California

ABSTRACT
RASCH, PHILIP J. AND E. MOREHOUSE.
LAURENCE EJect of static und
dynamic exercises on muscular strength and hypertrophy. J. Appl. Physiol.
II (I): 29-34. qs7.-The effects of 6-week programs of isotonic and
isometric exercises were observed in 49 male subjects. The 24 subjects who
performed isotonic exercises showed greater gains in strength and hyper-
trophy than did the 25 subjects who exercised isometrically. Tests of strength
were performed both in a position similar to that in which subjects were
exercised and also in an unfamiliar position. In addition, tests were used
which employed the musculature in a familiar and in an unfamiliar manner.
Whereas subjects showed strength gains in the tests when muscles were
employed in a familiar way, little or no gain in strength was observed when
unfamiliar procedures were employed. The findings suggest that the higher
scores in strength tests resulting from the exercise programs reflected
largely the acquisition of skill.

and isometric exerciseare Within the two groups the subjects were matched

B
OTH ISOTONIC
known to produce hypertrophy and as evenly as possible on the basis of height and weight.
One of each pair was then selected at random to exer-
increase the strength of skeletal mus- cise the left arm only and the other to exercise the right
cles. Whether these two methods of exercise arm only. The height and weight of each subject were
produce identical results is not certain. The re,corded. The girth of the upper arm was measured at
functional relationship between hypertrophy the greatest prominence of the biceps when the upper
and strength, the relative importance of learn- arm was raised to shoulder
fully contracted
height, the elbow flexors
and the palm down. For this purpose a
ing and intramuscular alterations in producing flexible steel tape marked in centimeters was applied
strength, the effects of exercise on contralat- with just enough pressure to make contact with the
era1muscles,the persistenceof strength gains skin. Readings were made to the nearest 0.1 cm.
Strain gauge dynamometer measurements of
and the specificity factor in testing strength strength were obtained by means of a Baldwin SR-4 load
are also obscure. The investigation reported cell, which was firmly attached to the floor. Changes
in this paper was designed to elucidate these in tension exerted against the sensing element in the
questions. cell were translated into proportional changes in output
voltage, which were electronically amplified and re-
PROCEDURE corded on an ink-writing dynograph. Comparison of
the deflection of these recordings with those produced
The subjects for this study were healthy adult male by known weights hung from the load cell made it
students from the junior class of the College of Osteo- possible to calibrate the amount of tension exerted.
pathic Physicians and Surgeons. The group which
To measure elbow flexor strength, a flexible airplane
performed isotonic exercise consisted originally of 26
cable was led from the load cell to overhead pulleys,
subjects. One subject dropped out before completion
of the study and a second was eliminated following a down to a floor pulley and upward again to a stirrup
marked weight loss resulting from a strict diet. The handle. Facing the floor pulley, the subject held the
group which performed isometric exercise consisted of stirrup handle with his palm up, his hand in line with
25 subjects, all of whom completed the experimental his forearm and upper arm perpendicular to the floor,
program. close to his body but not braced against it. By use of a
goniometer, his forearm was placed in a position ex-
Received for publication September 7, w6* tended IOO degrees from the position of his humerus,
1 Report No. 20-56. as illustrated in figure I. The subject steadily contracted

29

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Copyright © 1957 American Physiological Society. All rights reserved.
 P. J. RASCH AND L. E. MOREHOUSE Volume II

arily exercised to one unfamiliar to him, the subject

was tested in a position in which the strength of the
elbow flexors could be measured, but one in which he
did not exercise during the training period. He lay
supine on a plinth, feet braced against a footboard,
knees extended, upper arm on the plinth, forearm and
hand at an angle of roe degrees measured from the
position of the humerus, hand grasping the stirrup
handle. The cable connecting the handle with the load
cell was led over a wall pulley at an angle of 90 degrees
to the subject’s forearm. The subject then steadily con-
tracted his elbow flexors as strongly as possible. Arching
of the back, lifting of the arm from the table, extension
of the foot or other assistive movement was not per-
mitted.
To determine the effect on strength of changing
the method of testing to one which was not practiced
during the training period a modification of the Martin
test (I) was employed. The subject lay supine on a
plinth, feet braced against a footboard, knees extended,
upper arm on the plinth, forearm at an angle of 80
degrees as measured from the position of the humerus
and the hand in line with the forearm. The subject
grasped the stirrup handle, the end of which was hooked
to a spring balance. The investigator held the handle
of the balance in one hand and the body of the spring
balance in the other. At the command, ‘Ready’ the
subject maximally contracted the elbow flexors a a
FIG. I. Testing subject for elbow flexor strength. steady rate. Simultaneously, the operator pulled on
Subject is grasping a stirrup handle which is connected the handle of the balance in the opposite horizontal
through a series of pulleys to a strain gauge dynamom- direction. Tension was developed without jerking and
eter. Change in tension or compression of the cell was steadily increased until the resistance of the sub-
ject was overcome and the forearm pulled into exten-
produces change in output voltage of strain gauge.
Output from strain gauge is amplified and recorded by sion. At this breaking point the command, ‘Stop,’ was
given and the maximum reading on the scale recorded.
physiological data integrator.
FIG. 2. Testing subject for arm elevation strength. The training program of the isotonic group con-
sisted of progressive resistance exercises, with the
Chain and snap-hook allows for adjustments for dif-
ferences in heights of subjects. Strain gauge dyna- resistance _ furnished by plate-loading dumbbells.
mometer converts tension into electrical energy which Each subiect determined the weights with which he
is amplified and recorded by physiological data inte- could perform a maximum of five eibow flexions (curls)
grator. Subject exerts greatest amount of effort possible and five arm elevations (presses). The exercises were
in an upward arm elevation without bending the body performed in the standing position. In curling, the
or raising the heels. subject, with his arm at his side and palm forward,
flexed his elbow until his hand was brought up to his
shoulder. In pressing, he started with the weight at
his elbow flexors as strongly as possible. Jerking, latero- shoulder level and elevated it until his elbow was
flexion, backward bending, shifting of weight, move- straight and his arm close to his ear. Five such flexions
ment of the upper arm or other accessory movement or elevations constituted a ‘set.’ The exercise period
was not permitted. consisted of three sets of presses and three of curls,
To measure arm elevation strength, the subject each set being followed by.a 3-minute rest period. The
stood with the arm to be tested next to the strain length of these rest pauses was found to be optimal by
gauge. The upper arm was pendant from the shoulder, Clarke, Shay and Mathews (2). Loads were increased
the elbow flexed and the hand turned to mid-position in accordance with the subject’s improved ability to
in the normal starting position assumed by an individual move them. Exercises were practiced 3 days a week-
about to press a dumbbell to arm’s length overhead. Monday, Wednesday and Friday. Each Wednesday
The stirrup handle was placed in the subject’s hand the girth of the flexed upper arm of each subject was
and the length of the cable adjusted accordingly. This measured and the strength of the flexors and arm
position is shown in figure 2. The subject then endeav-
elevators was tested by use of the strain gauge dyna-
ored to elevate his arm directly upward as strongly as
mometer.
possible. Jerking, lateroflexion, shifting of the hips,
Because there is no known satisfactory method of
movement of the knees or feet or other assistive ma-
equating the energy expenditure in isotonic and
neuver was not permitted.
To compare the effect on strength of changing the isometric exercise, it is difficult to make quantitative
position of the subject from that in which he custom- comparisons between these two forms of activity. This

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Copyright © 1957 American Physiological Society. All rights reserved.
 JOY 1957 EFFECT OF STATIC AND DYNAMIC EXERCISES 3r
problem has been studied by Starr (3), but thus far a
practical solution has not been achieved. Preliminary
observation showed that subjects in the isotonic group
required about 15 seconds to complete a single set of
isotonic exercises and that they arbitrarily selected a
weight equal to approximately two-thirds of the amount
required to perform a single movement. On this basis,
a training program which consisted of the subject’s
exerting and maintaining for 15 seconds an isometric
strain equal to two-thirds of his maximum strength
was established for the isometric group. The positions
assumed for these exercises were identical to those
assumed for the strain gauge tests and are shown in
figures 3 and 4. The subjects performed three isometric
elbow flexions (curls), each separated by a Q-minute
rest period. The effort was not perfectly isometric but
nearly so, since, as a result of compression of the spring
in the scale, a strain of 70 pounds against the scale pro-
duced a movement of less than 35 inch. The subjects
trained on Mondav. Wednesdav and Fridav. Thev were
tested on the stram’gauge each Monday and during the
three weekly training periods used two-thirds of the
tension recorded. Tension was thus increased in accord-
ance with increases in strength as a result of training.
Neither the supine nor Martin type exercise was per-
formed during the training period.
Using the curling and pressing exercises described
above, the subjects trained for 6 weeks. At the end of
the training period all tests were repeated. It was FIG. 3. Subject engaged in isometric elbow flexion
recormised that the practice of one exercise might exercises. Amount of tension shown on scale is equal
affect the scores made in the other, but since hyper- to two-thirds of subject’s maximum isometric strength
trophy was being measured, it was considered desirable and is maintained for 15 sec.
to use both forms. The subjects then refrained from FIG. 4. Subject engaged in isometric arm press exer-
these exercises for a period of 6 weeks, at the end of cise. Amount of tension shown on scale is equal to two-
which time the tests were repeated in order to observe thirds of subject’s maximum isometric strength and is
the persistence of alterations in hypertrophy and maintained for 15 sec.
strength. A change in strength or hypertrophy was con-
sidered statistically significant if the computed t was In the arm elevator exercises, the subjects
significant at the .05 To level of significance.
in the isotonic group showed a significant
RESULTS mean increase of 25.33 pounds in strength in
the exercised arm and 24.54 pounds in the
Strength. The effects of isotonic and iso- unpracticed contralateral arm. The isometric
metric exercises on strength and hypertrophy
group showed a significant mean increase of
are presented in table I. In the elbow flexion 12.88 pounds in strength in the exercised arm
exercises, the mean strength for the isotonic
and a nonsignificant mean increase of 7.92
group significantly increased by 14.38 pounds
pounds in the contralateral arm. At the end
in the exercised arm and 11.58 pounds in the of the rest period the mean strength of the
unpracticed contralateral arm. However, in
isotonic group showed no significant change;
the isometric group there were no significant however, the mean strength in the isometric
changes in strength in either the exercised group decreased significantly by 11.64 pounds
arm or in the unpracticed contralateral limb. in the exercised arm, but no significant change
During the rest period there was a significant was noted in the unexercised arm.
mean increase of 1.92 pounds in the strength The changes in strength recorded during
of the unpracticed contralateral arm in the the unpracticed tests presented a very differ-
isotonic group, but no significant change in ent picture. In the supine elbow flexion test
strength in the exercised arm was recorded. subjects in the isotonic group showed a sig-
In the isometric group the exercised arm nificant mean increase of 3.37 pounds in
showed nonsignificant losses after the rest strength in the exercised arm and 2.83 pounds
period. in the unpracticed contralateral arm. Subjects

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Copyright © 1957 American Physiological Society. All rights reserved.
 32 P. J. RASCH AND L. E. MOREHOUSE Volume II

TABLE I. SUMMARY OF CHANGES IN STRENGTH strength of the exercised arm and 2.83 pounds
AND HYPERTROPHY FOLLOWING EXERCISE in the unpracticed contralateral arm; the iso-
AND REST
metric group showed a mean increase of 4.92
pounds in strength in the exercised arm and
3.16 pounds in the unexercised contralateral
Exercise limb. At the end of the rest period, neither
/ Strength its;, Strength /z the isotonic nor the isometric group showed
significant changes in strength in the exer-
lb. cm lb. cm cised arm, but the isotonic group showed a
Elbow jlexion significant increase in the strength of the con-
Isotonic tralateral limb.
Exercised 14.38*1.22* -79 - .60* Hypertrophy. As a result of the elbow flex-
Contralateral 11.58” .34t 1.921 -.q$
ion and arm elevation exercises, the mean
Isometric
Exercised 1.96 l59* -2.84 .q hypertrophy of the exercised arm increased
Contralateral -1.68 -44 -2.16 .I8t significantly in both groups. There was an
Arm elevator increase of I. 22 cm in the girth of the fully
Isotonic flexed upper arm and an increase of 0.34 cm
Exercised 25*33* -71 in the unpracticed contralateral arm. In the
Contralateral 24 54*
l
1.17 isometric group there was a mean increase of
Isometric 0.59 cm in the girth of the exercised arm and
Exercised 12.88$ -11.641
Contralateral -6.20
a mean increase of 0.40 cm in the unpracticed
7.92
contralateral arm. At the end of the rest pe-
Unpracticed supine, elbow flexion
riod there were significant changes in the girth
Isotonic
measurements in the isotonic group. The girth
Exercised 3 l 37$ 4.96”
Contralateral 2.835 4*19* of the exercised arm decreased a mean of 0.60
Isometric cm, whereas the girth of the unpracticed con-
Exercised 5 l 92 I-44 tralateral limb decreased a mean of only o. 15
Contralateral 5.48 -.20
cm. In the isometric group there were no sig-
ModiJied Martin test nificant changes in the girth of the exercised
Isotonic arm; however, the girth of the contralateral
Exercised 5 .oo* - -33 arm increased a mean of o. 18 cm, which was
Contralateral 2*83t I.841
Isometric
significant.
Exercised 4.92” -.84
Contralateral 3.16” -.20 DISCUSSION

* .001 Level of significance. Hypertrophy-Strength Relationship. The re-

t .OI Level of significance. lationship between hypertrophy and strength
$ .05 Level of significance. is obscure. The girth measurement of the
flexed upper arm of the limb to be exercised
in the isometric group showed no significant was correlated with elbow flexor strength as
increases. After the rest period, the isotonic measured on the strain gauge prior to the
group showed significant mean increases of exercise period. This yielded r = .164, which
4.96 pounds in strength in the exercised arm was not statistically significant. After the
and 4.19 pounds in the unpracticed contra- exercise period, these two measurements cor-
lateral arm. The isometric group showed related r = .389, which was significant. In-
no significant increases in strength in either creases in girth correlated with increases in
the exercised or the contralateral arm. strength Y = .422, which was significant. In
In the modified Martin test, in which the previous studies Carpenter (4) reported that
subjects resisted the pull of a spring scale in young women y = .53 between the girth of
against the partially flexed elbow, both groups the extended upper arm and the strength of
showed significant mean increases in strength the forearm flexors, as measured by the Mar-
following exercise. In the isotonic group there tin technique. Clarke (5) reported Y = .55 be-
was a mean increase of 5.00 pounds in the tween girth measurements of the flexed upper

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Copyright © 1957 American Physiological Society. All rights reserved.
 JUY 19.57 EFFECT OF STATIC AND DYNAMIC EXERCISES 33

arms and cable tension strength tests in a closely related parts. Recently Hellebrandt
group of male subjects. McMorris and Elkins (8) suggestedthat cross-educationmay result
(6) found Y = .I 7 between the mean gain in from simultaneous discharge of efferent im-
circumference and the mean gain in strength pulses over bilateral pathways.
of elbow extension following weight training A large part of the learning resulting in in-
exercises. The fact that Clarke’s subjects were creased strength of elbow flexion may consist
physical education majors, who presumably of appropriate training of the antigravity
had a minimum of fat over their muscles, muscles of the body to compensate for the
might well explain the discrepancy between effect on body balance of the continually
his findings and those of the present study, changing position of a weight equal to a fairly
while Carpenter’s technique for strength test- high percentage of the body’s weight moving
ing (Martin test) is not comparable with that through an arc of approximately 180 degrees
employed in the present study (strain gauge). at a constantly changing distance from the
McMorris and Elkins measured girth, but body. This, together with other learning fac-
with the subject’s arm in a position different tors, such as more efficient control of the
from that employed in this study, and the neural mechanism governing the cocon trac-
effect of this difference cannot be estimated. tion phenomenon and overcoming of psycho-
Strength Training. It will be observed that logical barriers, may be responsible for the
the increases in strength following isotonic considerable increase in strength commonly
training were considerably larger when the observed by an individual during the first 2 or
subject was tested in the position in which he 3 weeks of weight training. It seemsunlikely
practiced the exercises (erect) than when that the actual increase in contractile strength
tested in a position (supine) or by a technique can be attributed entirely to the effects of the
(modified Martin) unfamiliar to him. This six or nine training sessions routinely com-
suggeststhat these increasesmay have been pleted during that time.
largely the result of learning rather than ac- Once the necessary adjustments have been
tual increases in muscular contractility. It made by one side of the body as a result of
does not seem likely that isotonic exercise unilateral training, patterns are established
practiced with one arm could result in a simi- which are readily available to the other side
lar increase in strength in the unpracticed con- of the body, thereby producing part of the
tralateral arm if this increase were dependent contralateral effect. Problems of readjusting
upon actual changes in contractile strength. the center of gravity in order to preserve body
Observations of the subjects during the train- balance are lessseriousin arm elevation exer-
ing period suggestedthat with both isotonic cisesthan in elbow flexion exercises.To some
and isometric exercise there tended to be more extent, this may be reflected in the fact that
or less tension in the contralateral arm during the subjects showed greater increases in arm
unilateral exercise, such tension appearing to elevation strength.
increase as the exercise became more difficult The results obtained in the supine elbow
for them. In effect, this may be considered a flexion test are consistent with such a theory,
form of isometric exercise, which possibly was since alteration of the individual’s posture
responsible for the slight increases in hyper- would negate the advantages acquired by his
trophy in the contralateral arm. having learned to compensate for changes in
An alternative explanation is that these body balance in the erect position. Somewhat
changes resulted largely from a ‘transfer of comparable conditions existed when the means
training’ or ‘cross-education.’ Over 50 years of testing was changed from the strain gauge
ago Davis (7) studied the contralateral effects to the modified Martin technique, with the re-
of unilateral exercise designed to increase sult that the subject lost the ‘feel’ of the pro-
speed, strength or accuracy in the exercised cedure. It will be noted that the actual im-
arm. He reported that the effects of such exer- provement shown by the modified Martin test
cises were transferred in some degree from the was similar to that shown by the supine elbow
exercisedto unexercised parts of the body, the flexiontest. Possibly the increase in strength
transfer being greatest in symmetrical and recorded by means of the unpracticed modi-

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Copyright © 1957 American Physiological Society. All rights reserved.
 34 P. J. RASCH AND L. E. MOREHOUSE Volume II

fied Martin test with the subject in the un- almost nothing happen’ and that this type of
practiced supine position represents the actual exercise was boring. Several individuals com-
increase in muscular contractile strength, and plained of discomfort in the shoulder area dur-
the difference between this figure and that re- ing arm elevation tests. In view of their nega-
corded for the practiced position represents tive attitude, there may be some question as
the increase in muscular strength actually re- to whether subjects would voluntarily work as
sulting from increased skill. If this theory is hard under isometric conditions as under iso-
tonic.
correct, it would suggest that, when used as a
therapeutic tool, contralateral exercises espe- REFERENCES
cially selectedto strengthen a given area would I MARTIN, E. G. Physiol. Rev. I : 454, 192 I.
produce more satisfactory results than would 2: CLARKE, H. H., C. P. SHAY AND D. K. MATHEWS.
general strengthening exercises. J. Assn. Phys. & Ment. Rehab. 8: 184, 1954.
STARR, I. J. Appl. Physiol. 4: 21, 1951.
It is suggestedalso that isotonic exercises 3* CARPENTER,
4= A. Res. Quart. 9: 3, 1938.
probably produce better results from the psy- 5. CLARKE, H. H. Res. Quart. 25 : 134, 1954.
chological as well as the physiological aspects. 6. MCMORRIS, R. 0. AND E. C. ELKINS. Arch. Phys.
Subjects in both groups expresseda dislike for Med. 35: 421, 1954.
7- DAVIS, W. W. Studies Yale Psychological Laboratories.
isometric effort. They complained that it was 6: 6, 1898.
frustrating to exert their full strength and ‘see 8. HELLEBRANDT, F. A. J. Appl. Physiol. 4:136, 1951.

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Copyright © 1957 American Physiological Society. All rights reserved.