THE EFFECTS CP ISOTONIC AWJ ISOMETRIC EXERCISES
ON HEART KATE AIm'B BLOOD PRESSURE AND THEIR
RELATIONSHIPS TO PHYSICAL WORK CAPACITY
IN COLLEGE MEN
AiX
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Major Professor
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Minor frci'esao'y^
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Coaitriittee
Mem&ft;;
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/esc; c-iV>&e School of Education
of thev(.-ra.ci'uate 6chool
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James, Sam E. , The Effects of Isotonl?„ and 1 son;etri.S.
Exercises OR Heart Rate and Blood Pressure and TheJr
Relationshl2§. to Physical work Capacity In College, &en.
Doctor of Education (College Teaching), August, 1973» 103 PP«»
20' tables, b illustrations, bibliography, 49 titles.
This study Investigates the effects of isotonic and
isometric exercises on heart rate and "blood pressure arid
seeks to determine the relationship of these effects to
physical work capacity.
A pilot study was conducted with 31 raale university
students to locate an isometric workload which would be
equal in oxygen cost to a ten-repetition isotonic exercise
•wltd 60 per cent of the .nr-axlraurK strength.
The exercises
were performed on a bench designed to exercise the quadriceps
IF a sole group by knee extension.
There was no significant
difference between the oxygen cost of the isotonic exercise
and that of an isometric exercise performed for twenty
seconds viith 90 per cent of the maximum strength.
Therefore,
these two exercises were used for comparison in the ir.ain
study.
Thirty-two male university students were used as
subjects for the main study, whose data included oxygen
consumption, heart rate, blood pressure, and physical work
capacity.
Oxygen consumption was determined by an oxygen
1
consumption computer.
Heart rate was monitored "by a physio-
graph at rest, during exercise, and for two minutes of
recovery.
Blood pressure was determined by an electro-
sphygmomanometer and recorded by a physiograph, at rest and
every fifteen seconds during two minutes of recovery.
Physical work capacity was determined by the Astrand test
for predicting maximum oxygen uptake.
The oxygen-consumption collection showed the two exercises equal in oxygen cost, confirming the findings of the
pilot study.
The heart rate rose significantly as a result
of both exercises and returned to the resting level rapidly
after exercise.
There was no significant difference between
the heart rates for the two exercises.
Systolic blood pressure rose signifIcantly as a result
of both exercises and returned to normal rapidly.
However,
it was significantly higher as a result of the isotonic
exercise.
Diastolic blood pressure decreased, significantly
as a result of the two exercises and returned to normal
rapidly.
The pattern of the response was somewhat different
and decreased significantly more as a result of the isometric
exercise.
Pulse pressure rose significantly as a result of
both exercises and returned to normal rapidly.
The response
was significantly greater for the isometric exercise.
The totals of all measurement times were added together
for heart rate and blood pressure.
The resting value for the
same time period was subtracted from this total, to determine
3
the cost of each form of exercise.
Systolic "blood pressure
was significantly greater as a result of the isotonic exercise , the only significant difference.
Physical work capacity
was shown of no value in predicting the response of the heart
rate and various measures of blood pressure to either the
isotonic or the isometric exercise.
In conclusion, either isotonic or isometric exercise
results in significant changes in heart rate, systolic and
diastolic blood pressures, and pulse pressure.
The patterns
of the heart rate, systolic blood pressure, and pulse pressure
are similar for the two modes of exercise.
The patterns of
the diastolic blood pressure responses are somewhat similar
but irregular.
Physical work capacity is of no value in pre-
dicting the cardiovascular stress caused by isotonic and
isometric exercises.
Systolic 'blood pressure and pulse
•pressure is significantly greater for an isotonic exercise.
Diastolic blood pressure is significantly lower for an
isometric exercise.
THE EFFECTS CF ISOTONIC AND ISOMETRIC EXERCISES
ON HEART RATE .AND BLOOD PRESSURE AND THEIR
RELATIONSHIPS TO PHYSICAL 'WORK CAPACITY
'IN COLLEGE MEN
DISSERTATION
Presented to the Graduate Council of the
•North Texas State University in Partial
Fulfillment of the Eeouiremants
For the Degree of
DOCTOR OF EDUCATION
By
Sait E. James, Mje A.
A 1|
Denton, Texas
August, 1973
TABUS OP COlvTEKTS
-rage
-.
LIST OF TABLES
LIST OP ILLUSTRATIONS."
v
>;li
Chapter
I.
INTRODUCTION
.
X
Statement of the Problem
Purposes of the Study
Hypotheses
Background and Significance of the Study
Definition of Terms
Limitations
Basic Assumptions
Instruments
Procedures for Collecting Data
Procedures for Analysis of Data
II.
EQUATING ISOTONIC AKD ISOMETRIC WORK
21
Heart Rate During Isotonic and Isometric
Exercises
Blood Pressure During Isotonic and
Isometric Jixercises
III.
PROCEDURES FOR COLLECTING DATA. .
3?
M easurements
Pilot Study
Collection of Data
Procedures for Analysis of Data
IV.
PRESENTATION OP DATA.
Findings of the Study
Summary and Discussion
iii
. . » .
60
iv
TABLE OP CONTENTS—ContInued
Chapter
V.
Page
SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS . .
93
Summary
Conclusions
Recommendations
BIBLIOGRAPHY
. . . . . . . .
.
99
LIST OF TABLE,
Table
Page
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
Analysis of Variance of Oxygen Cost
of the Four Exercises.
52
Cubic Centimeters of Oxygen Cost and
Statistical Comparison of the
Isotonic and the Isometric
Exercises. . . . .
. . . . . .
53
Oxygen Consumption and Oxygen Cost in
Cubic Centimeters for Isotonic and
Isometric Exercises
61
Analysis of Variance for Heart Rate
Measurements During Isotonic and
Isometric Exercise and Recovery
62
Heart Rates During Isotonic Exercise
and Recovery
. .
Analysis of Variance for Systolic Blood
Pressure During Isotonic and
Isometric Exercise and Recovery
6^
65
Systolic Blood Pressure at Rest and
During Recovery from Isotonic
Exercise
.
67
Analysis of Variance for Diastolic
Blood Pressure During Isotonic
and Isometric Exercise and
Recovery
. .
68
Diastolic Blood Pressure at Rest
and During Recovery from Isotonic
Exercise
7.3
Analysis of Variance for Pulse Pressure
During Isotonic and Isometric
Exercise and Recovery
71
Pulse Pressure at Rest and During
Recovery from Isotonic Exercise. . . . .
73
LIST OP TABLES-
Continued
Table
XII.
XIII.
XIV.
XV.
XVI.
XVII.
XVIII.
XIX.
XX.
• Page
Heart Rates During Isometric Exercise
and Recovery . , . . .
Systolic Blood Pressure at Rest and
During Recovery from Isometric
Exercise . . . . . . . . .
75
.
70
Diastolic Blood Pressure at Rest and
During Recovery from Isometric
Exercise . .
. . . . . . . .
77
Pulse Pressure at Rest and During
Recovery from Isometric Exercises. . . .
79
Systolic Blood Pressure Changes During
Recovery from Isotonic and Isometric
Exercises. . . .
. . . . . . .
80
Diastolic Blood Pressure Changes During
Recovery from Isotonic and Isometric
Exercises. . . . . . . . . . . . . . . .
81
Pulse Pressure Changes During Recovery
from Isotonic and Isometric
Exercises.
83
T-Tests for Heart Rate, Systolic and
Diastolic Blood Pressure, and Pulse
Pressure Cost of Isotonic and
Isometric Exercises
Correlation Coefficients Between Physical
Work Capacity and Wean Change in
Heart Rate, Systolic and Diastolic
Blood Pressure, sind Pulse Pressure
Cost of Isotonic and I sometrio
Exercises. . . „ . , , . . .
37
LIST OP ILLUSTRATIONS
Figure
Page
1.
Mean Heart Rate
. . . . . . . . . . .
2.
Mean Systolic Blood Pressure.
66
3.
Mean Diastolic Blood Pressure
69
^.
Mean Pulse Pressure . .
72
vii
63
CHAPTER I
INTRODUCTION
Both isotonic and isometric resistance exercises are
•j
'recognized as beneficial for developing strength.
Daykln"
states that isometrics are the therapist's tool for a quick
return of strength after long periods of bed rest, and are
p
beneficial in geriatric treatment.
McCloy
suggests that
cardiac patients might be able to maintain muscular strength
through the use of isometric contractions vjith long rest
intervals between such efforts.
Other researchers- have.opposed both isotonic and
isometric resistance exercises for cardiac patients because
of the danger of inducing a Valsalva maneuver.
The Valsalva
maneuver occurs because of an increase in interth.orac.lc
pressure, resulting frpm breath holding daring lifting and
Is -particularly dangerous for cardiac patients. Jackson^
1
•'"Herbert P.. Daykln, "The Application of Isometrics is
Geriatric Treatment,K American Corrective Therapy Journal,
iuu
196?),
205
W T (November-December,
'
'
..
:™v™ .
'^Charles H. McCloy, "Something New Has Been Added,"
Journal of the Association for Physical and Cental Rebabl11tati.cnf IX (January-February, 1955) »
' """""
3. Dreal, "Risks of weight Lifting," Journal off
the American M e d i c a 1 A B sociat :l on, OCX 11 (June-, 1970),, 226?;
A. R. Lind, "Cardiovascular Responses to Static Exercise
(Isometrics, Anyone?}," Circulation, XLI ('February, 1970) » V;4.
it
"David H» Jackson, "3: some trie (Dynamometer) Stress
Testing in Coronary Heart Disease," Alabama Journal of
&S41&S1 Silence, VII {July, 1970) , 3I0-3T2.
—
™
2
employed the use of a grip dynamometer to screen subjects with
heart disease.
Fifty-seven per cent of those with heart
disease had an abnormal electrocardiograph reading or experienced chest pain during the isometric exercise.
The.se
characteristics did not occur in non-cardiac patients.
Since heart disease is row recognized as the number one
cause of death in the United States, it is Imperative that
proper treatment be given to heart disease patients.
Yet
isotonic and Isometric exercises are employed dally by
young and old, healthy and unhealthy, without a complete
knowledge of the immediate cardiovascular effects of the
two modes of exercise.
Much of the research vshich compared
isotonic and isometric exercises employed arbitrary work
loads, which were not physiologically equal.
these studies is therefore limited,
The value of
Adequate comparisons
can be made only'when equal physiological work loads are
compared.
In this study oxygen consumption was employed
as the means of equalizing work load.
There is a definite need to show the relationships of
the cardiovascular responses during isotonic and isometric
exercises to cardiovascular fitness.
Researchers^ have
^Breal, or.). cit., p. 2267; Daykin, op. cit. , p. 205»
A. R. Lind, "Cardiovascular Responses to Static Exercise
(Isometrics, Anyone?)," Circulation; XLI (February, 1970),
17^; A. R. Lind and G. to. Kcflicol^ "Cardiovascular Responses
to Holding and Carrying 'weights by Hand and by Shoulder Harness," Journal of Applied Physiology, XXV (September, 1968),
606-607; William D. FicArdle and Guide F. Foglia, "Energy
Cost and Cardiorespiratory
Stress in Isometric and Weight
Training Exercise,1" Journal of Sports Medicine and Physical
Fitness. IX (March, 1*969)","2.37 "
~
" '
suggested that heavy resistance exercises are both good and
bad for the cardiac patient and the bedridden patient, but
the literature fails to show how isotonic and isometric
exercises affect normal individuals at varying levels of
fitness,.
Statement of the Problem
The problem of this study was to determine rhe effects
of isotonic snd isometric exercises on heart rate and blood
pressure and to determine the relationships of these
effects to physical work capacity.
Purposes of the Study
In recent years considerable research has been completed which compared the merits of isotonic and isometric
exercises.
One purpose of this study was to determine if
one of these forms of exercise results .in greater cardiovascular stress when the work loads were equalized.
A
relationship is known to exist between cardiovascular
fitness and heart disease.
Researchers have opposed both
forms of exercise for cardiac patients'.
The question arose
as to whether cardiovascular stress resulting from isotonic
and isometric exercises would be greater for the person
who possessed good cardiovascular fitness than for the
person who possessed poor cardiovascular fitness.
The
second purpose of the study was to determine the relationships
"between cardiovascular stress resulting from isotonic and
Isometric exercises and cardiovascular fitness as determined
by physical work capacity.
Hypotheses
To carry out the purposes of this study, the following
hypotheses were formulated:
1.
Isotonic exercise will result in no significant
change in the following -variables:
a.
heart rate during exercise and during each
fifteen seconds of recovery for two minutes after
exercise,
b.
systolic blood pressure during each fifteen
seconds of recovery for two minutes after exercise+
c.
diastolic blood pressure during each fifteen
seconds of recovery for two minutes after exercise,
d.
pulse pressure during each fifteen seconds
of recovery for two minutes after exercise.
2.
Isometric exercise will result in no significant
change in the following variables:
a.
heart rate during exercise and during each
fifteen seconds of recovery for two minutes after
exercise,
b.
systolic blood pressure during each fifteen
seconds of recovery for two minutes after exercise,
5
c.
diastolic blood pressure during each fifteen
seconds of recovery for tvo minutes after exercise,
d.
pulse pressure during each fifteen seconds
of recovery for two minutes after exercise.
3«
There will be no significant difference in the mean
'change in the following variables resulting from isotonic
and isometric exercises which have been equalised;
a.
heart rate during exercise and during each
fifteen seconds of recovery for two minutes after
exercise,
b.
systolic blood pressure during each fifteen
seconds of recovery for two minutes after exercise,
c.
diastolic blood pressure during each fifteen
seconds of recovery for two minutes after exercise,
d.
pulse pressure during each fifteen seconds
of recovery 'for two minutes after exercise.
4.
There will be no significant difference in the
following changes resulting from isotonic and isometric
exercises:
a.
the total change in heart beats starting with
exercise and continuing for two minutes after exercise,
b.
the total change in eight systolic blood
pressure measurements during two minutes of recovery
from exercise,
c.
the total change in eight diastolic blood
pressure measurements during t w o minutes of recovery
from exercise,
d.
the total change in eight pulse pressure
measurements during two minutes of recovery from
exercise.
5.
There will be no significant correlations between
physical work capacity and the following changes resulting
from isotonic exercise:
a.
the total change in heart beats starting with
exercise and continuing for two minutes after exercise,
b.
the total change in eight systolic blood
pressure measurements during two minutes of recovery
from exercise,
c.
the total change in eight diastolic blood
pressure measurements during two minutes of recovery
from exercise,
d.
the total change In eight pulse pressure
measurements during two minutes of recovery from
exercise.
6.
There will be no significant correlations between
physical work capacity and the following changes resulting
from isometric exercise:
a*
the total change in heart beats starting with
exercise and continuing for two minutes after exercise,
b.
the total change in eight systolic blood
pressure measurements during two minutes of recovery
from exercise %
c.
the total change in eight diastolic blood
pressure measurements during two minutes of recovery
from exercise,
d.
the total change in eight pulse pressure
measurements during two minutes of recovery from
exercise.
7.
There will be no significant differences in the
correlations between physical work capacity and the following
changes resulting from isotonic and isometric exercises:
a.
the total change in heart beats starting with
exercise and continuing for two minutes after exercise,
b.
the total change in eight systolic blood
pressure measurements during two minutes of recovery
from exercise,
c.
the total change in eight diastolic blood
pressure measurements during two minutes of recovery
from exercise *
d.
the total change in eight pulse pressure
measurements during two minutes of recovery from
exercise.
8
Background and Significance of the Study
Lind and McNicol^ found that the amount of absolute
tension does not determine the cardiovascular response to
isotonic exercise, but that the relative tension of a given
muscle group determines this response.
Cardiovascular
responses to a given percentage ef maximum tension in a
small muscle group and a large muscle group were found to be
the same.
Two limbs contracting simultaneously at different
intensities resulted in greater blood flow to the limb with
the weaker contraction.^
Heart rate and blood pressure
was the same as for the stronger contraction only.
These
findings indicate that a linear relationship does not exist
between isometric work and cardiovascular responses.
Vihile
this finding is in agreement with Burger,^ Clarke 1 3 9
findings disagree.
Clarke"^ compared his findings with
. R. Lind and G. Vi. M c M c o l , "Circulation Responses
to Sustained Hand-Grip Contractions Performed During Other
Exercise, Both Rhythmic and Static," Journal of Physiology,
CXCII (October, 196?) , 595 > A. R. Lind and G. W. M c M c o l ,
"Cardiovascular Responses to Holding and Carrying 'Weights by
Hand and by Shoulder Harness," Journal of App3led Physiology.
XXV (September, 1968), 599•
'Lind and MoBicol, "Circulation Responses to Sustained
Hand-Grip Contractions," p. 598.
R
G. C. E, Burger, "Heart Rate and the Concept of
Circulatory Load," Ergonomics, XII (November, 1969)» 8599
David H. Clarke, "Energy Cost of Isometric Exercise,"
Research Quarterl.y, XXXI (March, 1962) , 3~6•
10
Ibid., p. 5•
those' of Henry and DeMoor :1 and found that oxygen debt Is
approximately k-J per cent, greater during isometric exercise
than during isotonic exercise.
Net oxygen Income was 19
per cent less during, isometric exercise at the same yjork
load.
This supports the hypothesis that occlusion of the
•blood vessels occurs during Isometric exercise.
Further
evidence was supplied in a later study by C l a r k e , ^ which
showed that grip strength decreased much faster from an
isometric grip exercise than from an isotonlc grip exercise,
This rapid decrease in strength is likely, due to lack of
oxygen resulting from occlusion of the blood vessels.
Folkow and others'^ found that the pumping action of the
muscle caused blood to flow out of the muscle during contraction and to flow in during relaxation.
Flow Increased
even after the vessels were dilated maximally.
1 ii
Shvartz x
found that an isometric military press of
one-half of maximum strength for forty-five seconds
1LX1
- Franklin M. Henry and Janice C. DeMoor, "Lactic and
Alactic Oxygen Consumption in Moderate Exercise of Graded
Intensity," Journal of Applied Physiology, XI (May, 1956),
608-614.
~
-^David H. Clarke, "Strength Recovery from Static and
Dynamic Muscular fatigue," Research Quarterly, XXXIV (October,
1963). 3^9-355.
1
3B. Folkow, P* Gaskell, and B. A. Waaler, "Blood Flow
Through Muscles During Heavy Rhythmic Exercise," Acta
Physlolopdca Scandinavia, LXXX (September, 1970) ,""65."
-^Esar Shvartz, "Effect of Isotonic and Isometric Exercise on Heart Rate," Research Quarterly, XXXVII (March,
1966), 123.
""
10
stimulated heart rate to the saiae extent as an isotonic
military press for the same duration and intensity.
He found
almost a two-fold Increase in heart rate with a maximum
isometric contraction for forty-five seconds.
Contrary to
this, N e l s o n ^ f o u n d no increase in heart rate during isometric exercise, ivhlle isotonic exercise resulted, in a
significant increase.
Sharkey
found that Isotonic exer-
cise performed for six minutes resulted in greater oxygen
consumption, heart rate, and blood pressure than isometric
exercise with the same weight and time duration.
McArdle
and Foglia^7 found that heart rate increased rapidly during
an eight-repetition max 1 muni isotonic' exercise and decreased
rapidly after exercise.
An isometric exercise of a six-
second duration resulted in th-j increase continuing after
1O
exercise, then decreasing rapidly.
Knox
reported that
when spring scales were pulled, into position and held for
twenty seconds, then released, there was an Increase of
heart rate at the time of pulling and releasing.
No such
•^Norman Nelson, "Nature of the Responses of the Heart
to Weight Lifting and 'weight Sustaining," unpublished
master's thesis, Department of Physical Education for Men,
University of Iowa, Iowa City, Iowa, 19391 pp. 20-21.
-^Brian J. Sharkey, "A Physiological Comparison of
Static and Phasic Exercise." Research Quarterly. XXXVII
(December, 1966), 52^•
"^McArdle and Foglia, op. cit. , p. 26.
. A. C. Knox, "The Effect of the Static and of the
Dynamic Components of Muscular Effort on the Heart Rate,"
Journal of Physiology, CXII1 (March, 1951)» 38.
11
increase was found when the subject remained in the Isoniecrie
position and the spring scales were placed in and removed
from his hands by an assistant«
lo
Some researchers^' havs noted that during isotonic
resistance exercise, systolic blood pressure always rises,
while diastolic blood pressure changes are insignificant
pn
or unpredictable,
Thompson"
found an increase in dias-
tolic blood pressure during isometric exercise, while
t ; -J
Sharkey"'
/HQ
and Kingmlnghae^'" found Increases in systolic
and diastolic blood pressure during both isotonic and
isometric exercises.
The research is conflicting In regard to the cardiovascular stress of isotonic and isometric exercises.
One
reason for this contradiction is the variation of work
loads from one study to another. Physicists have described
^ L u c ien Brouha and Edward P. Redford, Jr., "The
Cardiovascular System in Muscular Activity," Science and
fr'iedlcine of Exercise and. Sports. edited by Warren R.
Johnson (New York, i960), p. 188; J 1m Murray and Peter V.
Karpovich, weight Training in Athletics (Enprlewood Cliffs,
1959).
70
Clem
. Thompson, "Some Physiological Effects of
Isometric and Isotonic Work in Man," Research Quarterly,
XXV (December, 19520 , 4 3 1 ^ 8 2 .
23
"Sharkey, op. cit., p. 26.
2?
""Prahantha Kingminghae, "Static and Concentric Muscle
Contraction: Fi'fect on Blood Pressure and Pulse Rate,"
unpublished master's thesis, Department of Physical Education
for Men, University of Iowa, Iowa City, Iowa, 1963, p. 18.
1 -7
JL C
1*3ork as the force applied multiplied by the distance r-hrough
WHICH the object >38.8 moved*
One roo,y readily SOB that this
formula "would not apply to isometric exercise, In ^hicli
there is no movement.
Starr2^ attempted to equalize
isotonic and isometric exercises mathematically, but this
'was found to be inaccurate by Sharkey.^
Cooper made plain
his opinion on equalising work when he stated, "In wearohlng
for a method of equating different exercises, it was found
that oxygen or metabolic cost was the ideal common denominator.
Oxygen consumption shows the actual physiological
energy used in an exercise.
For this study oxygen consump-
tion was used to equalise the amount' of physiological work
done.
By comparing equal work loads the data are much more
meaningful.
Most of the research reviewed here was under-
taken with a sample size ranging from two to twelve subjects
which may help account for the varying findings.
The
literature has contained hypotheses about the effects of
isotonic and isometric exercises on the cardiovascular
system of the unfit person, but little has been done to
2
^Xsaac Starr, "Units for the Expression of Both Static
and Dynamic Work in Similar Terms and their Application to
Weight Lifting Experiments," Journal of Allied Ph£siolog£f
IV (July, 1951). 21-29.
Oh
Sharkey, o£. cit. , p. 52?.
^Kenneth H. Cooper, "Quantifying Physical ActivityHow and Why?" The Journal of the South Carolina Medical
Association, LXV:
-Sup7~l""to™No7 12~Ci)ecember, 19&9F. 39»
1.3
show the actual effects.
This study relates the findings
to the level of fitness as measured by a viork capacity test.
.Definition of Terms
C a I'd 1 ovascular Stye §s is indicated by heart rate and
blood pressure.
Isotonic Exercise is a muscle contraction which results
in a change in the angle of a joint.
For this study,
isotonic exercise was ten repetitions of knee extension
completed in twenty seconds with 60 per cent of the maximum
weight which the subject could lift one time.
Isometric Exercise is a muscle contraction which
results in no change in the angle of a joint.
For this
study isometric exercise was performed by holding the weight
with the knees at approximately a 14-5-degree angle for
twenty seconds.
The weight used was 90 per cent of the
maximum weight which the subject could lift one time.
Physical Work Capacity is the ability to do work or an
indication of the level of cardiovascular fitness.
For this
study physical work capacity was the ability to perform on
the bicycle ergometer»
Limitations
Limitations of this study were as follows:
1.
The study was limited to male students enrolled
in .norning physical- education classes at North Texas State
University during the spring and summer of 1972.
14
2.
Subjects were not selected on tha basis of body
type and ranged greatly In height and weight.
3.
The diet of the subjects was not strictly controlled,
Metabolic rate and oxygen consumption may vary considerably
due to consumption of different food types.
Oxygen con-
sumption was determined as if all subjects had consumed the
same food types.
k.
To implement a testing schedule, subjects were
tested from ?.*30 A.M. to 12:30 P.M., which could result in
a variation in oxygen consumption because of the length of
time since food consumption.
5.
The pilot study was limited" because resting
oxygen consumption was measured for only one minute.
Basic Assumptions
It is assumed that the subjects made an honest effort
to follow laboratory procedures and to perform the exercise
tests as Instructed.
Instruments
The isotonic and the isometric exercises were performed
on a bench designed to exercise the quadriceps muscle group
by knee extension.
The back rest was slanted at a 135 *
degree angle, and adjustments were made for leg length.
belt Kas used to stabilize the subject at the hips to
prevent excess movement of the body.
Selection of this
A
-
" •
1^
type of exercise was based or, the desire to employ a lar<?e
muscle group which would allow the upper body to remain
stable while heart rate and blood pressure were being
measured.
Strength was the amount of weight which the
subject could.lift one time, from a knee angle of 90 degrees
to a knee angle of 180 degrees.
Oxygen consumption was chosen as the measure of energy
expenditure bo equalize isotonic and isometric work.
Cooper^ states that oxygen consumption is the best means
of equalizing work.
Oxygen consumption was measured by an
oxygen consumption computer (Model occ 1000 - 10/60).
Physical work capacity -.'as measured by a desk model
physiograph (DMP-4A) with a curvilinear amplifier (CA-200)
and a cardiac preamplifier to record- heart rate while the
subject rode the bicycle ergometer at a given rate with an
increasing; work load,
Astrand and Rhyming^ have shown
this test to be an effective determiner of cardiovascular
fitness.
In order to show the cardiovascular stress of isotonic
arid isometric exercises, heart rate and systolic, diastolic,
and pulse pressure were measured.
Heart rate has long been
an acceptable measure of cardiovascular stress, but as
of
" Cooper, og. cit., p. 39*
C. Astrand and Irraa Rhyming, "A Nomogram for
Calculation of Aerobic Capacity from Pulse Rate During
SufcrcaximaX Work." Journal of Applied Physiology, VII .
(September, 1954), 218-222. ~ "
16
?8
Burger™
has shown, lr- is not satisfactory -when used alone.
It was measured the same as in the :<;ork capacity test.
The
physiograph was used to record blood pressure, which was
measured by an electrosphygmomonometer linear-core (ESG-300),
Procedures for Collecting Data
ZLlot S tudjr
Per r.iis si on was obtained from the ftorth Texas State
University physical education department to use male students enrolled in physical education classes as subjects
for this study.
Thirty-one students enrolled in a 9:00 A.M.
track and volleyball class during the spring of 19? 2 served
as subjects for the pilot study to equalize the isotonic
and isometric work loads.
All testing was administered in the physiology of
exercise laboratory at North Texas State University.
On
the first day of the pilot study, the subject was instructed
in laboratory procedure, tested to determine the maximum
amount of weight "which could be lifted one time, and allowed
to practice the isotonic and the isometric exercises.
On the second day, the subject performed the isotonic
exercise with 60 per cent of his maximum strength and the
isometric exercise for twenty seconds with 70, 80, and 90
per cent of his maximum strength.
^Burger, op,* cit. , p. 859«
The choice of these
1?
four exercise leads has based on experimentation with three
subjects who were not involved in the pilot study.
It was
estimated that the oxygen coflt of the isotonic exercise
would be no different from oxygen cost of one of the
isometric exercises.
These four exercises were performed
"in random order by drawing numbers from a box.
The isotonic
exercise was performed at the rate of one complete repetition
every bwo seconds and was controlled by a metronome.
The
exercise started on a verbal signal end stopped at the
completion of ten repetitions.
The range of movement was
from a knee angle of 90 degrees to a knee angle of 180
degrees.
The isometric exercise was* started on a verbal
signal and ended on a verbal signal after twenty seconds.
The weight was resting on a stand which would require the
subject to extend his knees to 14$ degrees to lift the
weight from the stand.
On the starting signal, the subject
placed his ankles against the bar and raised the weight
about an inch from the stand.
On the stopping signal,
he lowered the bar to the resting position.
Oxygen con-
sumption was measured for the four exercises starting
with exercise and continuing through four minutes of recovery.
The oxygen cost of each form of exercise was the
oxygen consumption starting with exercise and continuing
through recovery minus the resting oxygen consumption.
simple analysis of variance and Duncan®s multiple range
A
test 'were applied to the data.
There was no significant
difference in the isotonic lead and the isometric load when
90 per cent of the maximum lift was employed.
The .05 level
was used to reject the null hypothesis.
Data Pellection
Thirty-two male students from morning physical education
classes during the first summer session of 1972 were used as
subjects for the study.
On the first day at the laboratory,
the subjects who were used for data collection were measured
for strength and instructed in laboratory procedure.
On
the second day, the subject's age, height, and weight were
recorded; and then he rested on the exercise bench until
the heart rate, blood pressure, and oxygen consumption
became uniform.
He performed both the isotonic and the
isometric exercises on that day.
was randomized.
The order of the exercises
Heart rate was recorded at rest and con-
tinuously through exercise and two minutes of recovery.
Blood pr.ssure was recorded simultaneously every fifteen
seconds starting immediately after exercise.
Oxygen
consumption was recorded during five minutes of rest and
a five-minute period of time which began with each exercise.
The subject then performed the work capacity test on the
bicycle ergometer, as described by Astrand.^
The subject
0. Astrand, Ergomecry~Test of Physical Fitness»
Monark~Crescent AB, Varberg, Sweden, p. lo.
1?
"i' O CI © W 3. T, 11fi,t'- Vi c ~ k i ]opond braking resistance for six minutes,
lr".
« 4- x'lf!;y
f'
xur:
"pedal turns p.-r
Heart rate was recorded
uiinut.-v:.
«?uring the last fifteen seconds of each minute*
The test
viae ecisplete 'when the heart rats exceeded 130 "beats per
minute, n3th the last two minutes having a variation of no
.more than five beats per minute.
Provided the heart rate
did not stabilize above 130 beats per minute, the work
load was increased to a braking resistance of four kiloponds
and continued for six more minutes.
The results were
converted to maximum oxygen uptake per kilogram of- body
weight per minute and were recorded as the subject's work
capacity. ,
The decision to administer more than one test in the
same day was based on findings by Blair and o t h e r s , w h i c h
show that heart rate and blood pressure may vary significantly from one day to the next.
Others^l have had similar
findings in regard to oxygen consumption.
All subjects
were tested between 7•30 A.K. and 12:30 P.M. and were
instructed to refrain from eating food, drinking any
beverage, or smoking for one hour prior to the tests.
The
subjects were Instructed to avoid vigorous physical
activity on the day of the tests.
^Osteven Blair and Murray L. Vincent, "Variability of
Heart Rate and Blood Pressure Measurements on Consecutive
Days," Research Quarterly, XLII (March, 19?1), ?-13•
3-^McArdle and Foglla, 03). cit., p. 24.
v.--v>
20
Procedures for Analysis of Data
At the conclusion of data collection, the data were
statistically analyzed by the computer center at North Texas
State University and by hand.
The ,05 level of significance
•was arbitrarily selected to reject the null hypotheses.
Results of the study are reported in appropriate tables and
graphs in Chapter IV.
CHAPTEli II
EQUATING ISOTONIC AMD ISOMETRIC WORK
There have been many comparisons of Isotonic and
Isometric exercises«
However, the work loads employed in
these comparisons have In most instances been vastly
different.
Hence, the conclusions reached from these
studies may be questioned.
Coleman"'" used a weight which
could be lifted a max1mum of five times for an Isotonic arm
curl.
Tuttle and Horvath^ and Thompson^ made comparisons
using a bicycle ergometer for isotonic exercise and a hand
grip dynamometer for isometric exerci.ie.
Again, one may
readlly see that a disproportional amount of work was
performed*
Work has been defined as the distance an object is
moved multiplied by the weight of the object.
This formula
-'-Alfred E. Coleman, "A Comparison of Isotonic and
Isometric Exercises Performed on Contralateral Limbs,"
American Corrective Therapy Journal' XXIII (NovemberDecember, 19&9), 164.
2
"W. W. Tuttle and Steven M. Hcrvath„ "Comparison of
Effects of Static and Dynamic Work on Blood Pressure and
Heart Rate," Journal of A rolled Physiology. XX (March, 1957)
2953
'Clem W. Thompson, "Some Physiological Effects of
Isometric and Isotonic Work in Man," Research Quarterly,
XXV (December, 195*0» 481-482.
21
is inefficient in weight' lifting and isometric type exercise,for it does not take into account the time which an object;
is held without movement.
Starr** made an improvement on
this formula by adding a time factor, which would take into
consideration acceleration in lifting a weight and time of
'holding a weight isometrically.
A motion picture camera was
employed to record the movements in lifting.
The range of
the lift, the speed of the lift, and the isometric holding
time were graphed from the film,
the graph.
Work was computed from
Two major weaknesses exist in this formula.
First, it is expensive and time-consuming to employ.
Second,
it does not take into consideration the angle of the joint
when the weight Is being held isometrically.
Holding a
weight with the elbow at different angles will likely result
in different energy expenditures.
Starr5 stated that his
concern was measuring the amount of work done on a load, not
the amount of work done by the muscles involved.
A
and Rodahl
Astrand
state that physiological work is more closely
related to force developed multiplied by the contraction
time than to force developed multiplied by the displacement.
^Isaac Starr, "Units for the Expression of both Static
and Dynamic Work in Similar Terms and Their Application to
Weight Lifting Experiments," Journal cf Applied Physiology,
IV (July, 1951)» 23-24.
^Ibid., p. 22.
. 0. Astrand and Kaare Rodahl, Textbook of Work
Physlolog-y, (New York, 1970) , pp. 70-71.
23
Further, they state that all the extra energy output of
isometric exercise is converged to neat, while at least 75
per cent of the Isotonic is converted to heat.
Therefore,
isometric exercise may be more fatiguing and metabolically
less efficient than isotonic exercise.
Cooper^ states that
oxygen cost is the most effective means for equating exercises.
Bartles and others® found that oxygen cost during
isometric exercise varied greatly not only between subjects,
but within the same subject tested on different occasions.
McArdle and Foglia^ and Sharkey^ had similar findings.
Methods of measuring oxygen consumption have been timeconsuming and technical, which resulted in most research
being performed with small samples of subjects.
Oxygen cost of exercise remains the most efficient
and practical available means of measuring energy expenditure.
^Kenneth H. Cooper, "Quantifying Physical Activity—
How and Why?" The Journal of the South Carolina Medical
Association, LXV, Sup. 1 to No. 12 (December, 19^9)» 39*
O
Robert L. Bartles and others, "Effects of Isometric
Work on Heart Rate, Blood Pressure, and Oxygen Cost,"
Research Quarterly, XXXIX (October, 1968), ^39»
^William D. McArdle and Guldo F. Foglla, "Energy Cost
and Cardiorespiratory Stress in Isometric and Weight
Training Exercises," Journal of Sports x4ediclne and Physical
Fitness, IX (March, 1969) , 2-5•
•^Brian J. Sharkey, "A Physiological Comparison of
Static and Phasic Exercise," Research Quarterly, XXXVII
(December, 1966), 530*
^
• 24
11
Hansen and Magglo~A had two subjects ride the bicycle ergomet er for twenty-five minutes, •with varied work loads on
many different testing dates*
After the isotonic exercise
had proceeded for ten minutes, the subjects held weights
isometrically.at arm's length and continued the isotonic
exercise.
By use of a regression equation on the oxygen
consumption data, a means of comparing heart rates with
equal isotonic and isometric work was achieved.
The value
of this comparison is surely greater than complete arbitration.
The fact that two different muscle groups were
employed for the isotonic and isometric exercises casts
doubt on the value of comparison made from this method of
equating work.
Por example, heart rate may be affected by
the subject's breathing pattern, and the breathing pattern
may be quite different for an isometric exercise Involving
the arms and shoulders from one involving the legs and hips.
19
Clarke
studied the energy cost of holding three
different weight loads against the thighs for five minutes
while the knees were bent.
He compared his findings with
those of Henry and DeMoor,^ in which the subjects rode a
^-101e Evald Hansen and Mario Kagglo, "Static Work and
Heart Rate," Internat1onale Zeltschrlft fur Angewandte
Fhysio'logie, XVIIi"(I960)',
•^David h. Clarke, "Energy Cost of Isometric Exercise,"
Research Quarterly, XXXI (March, 1962), 5•
-^Franklin Henry and Janic C. DeKoor, "Lactic and Alactic
Oxygen Consumption in Moderate Exercise of Graded Intensity,"
Journal of Applied Physiology, XI (May, 1956), 610-614.
23
bicycle er<?ometer for five minutes at three different work
loads-
Oxygen costs of these two studies were considered
comparable.
This shows that equal work loads can be found
based on oxygen cost.
The need for a comparison of equal
isotonic and isometric work loads is apparent.
Further,
these work loads should be similar to those commonly
employed in weight training and rehabilitation programs.
The standards for selecting and equating the work loads
should be as follows:
1.
Use oxygen cost as the criterion for equating work.
2.
Use an exercise that is commonly used in weight
training or rehabilitation.
3.
Exercise the same muscle group in both the isotonic
and the isometric exercises.
'K
Use exercises for a time period comparable to
those being used in practice.
5-
_ •
Use the same time period for both the isotonic and
the isometric exercises.
6.
Use a sample of thirty or more subjects.
Provided
the above standards are followed, research may be completed
which has much more value for the practitioner.
Conclusions
based on such comparisons can be accepted and generalizations about the cardiovascular responses to isotonic and
isometric exercises can be made.
26
Heart Rate During Isotonic and Isometric Exercises
The fact that hear I; rate increases with the intensity
of work has long been accepted.
To illustrate, Prosh'^"
states that the more strenuous an exercise, the higher the
heart rate will rise and the slower It will return to normal,
Morehouse^ found that after lifting a twenty-five pound
•weight 5, 10, 15» 20, and 25 times, the recovery heart rate
was proportional to the number of repetitions.
In recent
years there has been much greater interest in the comparison
of heart rate during isotonic and isometric exercises.
The
literature is quite contradictory, but does show that both
forms of exercise result in an over-a11 rise in heart rate.
1£
Brouha and Redford
state that isometric exercise may
result in a slight rise, no change, or a slowing of heart
rate during the effort.
After the exercise, the heart rate
will remain elevated and will return to normal at a time
determined by the intensity of the exercise.
Nelson-*-?
"^Fredrick Prosh, "Effect of Exercise on Heart Rate,"
Research Quarterly, II (Decembers 1932), 76.
1Lawrence £• Morehouse, "A Study of the Responses of
the Heart to Various Types of Exercise," unpublished master's
thesis, Department of Physical Education, University of l'owa,
Iowa City, Iowa, 19^1, p. 25.
•^Luclen Brouha and Edward P. Redford, Jr., "The
Cardiovascular System in Muscular Activity," Science, and
Medicine of Exercise and Sports, edited by Warren R.
Johnson, (iiew York, i960) , p. 199>
•^Norman Nelson, "Nature of the Responses of the Heart
to Weight Lifting and. Weight Sustaining," unpublished
master's thesiss Department of Physical Education, University of Iowa, Iowa City, Iowa, 1939. PP* 20-21.
27
found no direct relationsnip between recovery heart rate and
Isometric exercise®
The heart raxes were said to be irreg-
ular and unpredictable.
Recovery heart rates were proper-
tlonal to the intensity of the isotonic exercise.
The
slowing of heart rate noted during the effort may result
•from the carotid, sinus reflex, which causes the heart rate
to decrease when the arterial blood pressure rises above
normal.
The slower heart rate "will in turn aid in lowering
the blood pressure.-'-®
Shvartz 1 ^ found that an isotonic and an isometric
military press performed for forty-five seconds with one-half
of the maximum load resulted in heart rates that were not
significantly different.
This was approximately a 43 per
cent increase from the resting value.
When maximum tension
was maintained Isometrically for forty-five seconds, there
was almost a two-fold increase in heart rate.
It was
suggested that isometric exercise may be valuable in
development and maintenance of cardiovascular fitness.
OA
Eartles and others"
found that a ten-second isometric
exercise with 60 per cent of the maximum strength performed
on a dynamometer from a squat position resulted in a slight
•^Robert P, Hushmer, Cardiovascular Dynamics (Philadelphia, 1961), p. 55.
19
Esar Shvartz, "Effect of Isotonic and Isometric
Exercise on Heart Rate," Research Quarterly, XXXVII (March,
1966), 124-125.
20
Bartles and others, o]p. c 11, , pp. l4.39~.V4O.
28
increase during exorcise, with the greatest increase
immediately after exercise.
Then there was a dramatic
decrease to near the resting level within thirty seconds
yn
after exercise.
MoArdle and Foglla"" found that heart
rate rose rapidly during an eight-repetition maximum isotonic exercise and decreased rapidly after exercise.
A
six-second Isometric exercise resulted In a continued rise
after exercise.
A continued Increase In heart rate imme-
diately after an isometric exercise of short duration is
99
common.
The explanation is not so common.
Knox
had one
group of subjects grasp the handle of a spring scale -and
pull a standard distance to where it'was held for twenty
seconds, then returned to the starting position.
There was
an immediate increase in heart rate at the start of the
pull.
After ten seconds of the isometric effort, there
was a slowing which lasted until the springs were released.
At this time there was another increase In heart rate.
An additional study was completed to eliminate the isotonic effort.
The springs were unattached at the distal
end, until the subject had his arms in position for the
isometric exercise.
Then the springs were attached and held
exactly as in the previous study.
After twenty seconds
the springs were unattached.. The Increase in heart rate
21
"McArdle and Foglia, op. cIt., p. 26.
99
J. A. G. Knox, "The Effect of the Static and of the
Dynamic Components of Pmscular Effort on the Heart Rate,"
Journal of Physiology, CXIII (March, 1951)< 37~39«
29
was significantly lower in. the last aiudy.
The increase in
heart rate a.fter exercise was approximately the same in "both
studies.
The Increase after exercise must be associated
with the isometric effort and not the movement of the
isotonic portion of the exercise in the first study.
Sharkey*^ had five subjects perform an isotonic and
isometric leg exercise for six minutes, using three different
work loads for each exercise.
Heart rate responses were
similar for the lightest work loads.
As the work load
Increased, heart rate increased much more for the isotonic
exercises.
The pattern of return to normal after exercise
was dependent upon the rise during exercise.
There was no
increase in heart rate after isometric exercise.
This
factor is apparently related to the duration of the exercise.
H a l l ^ and S t e v e n s ^ agreed with Sharkey in that heart rate
increased during'both isotonic and isometric exercises, but
the increase was significantly greater for the isotonic
^sharkey, o£. cit. , p. 5^5 •
24Floyd Lawrence Hall, "Heart-Rate Relative to Isometric
and Isotonic Muscle Contraction," unpublished master's thesis,
Department of Physical Education, University of Iowa, Iowa
City, Iowa, 1962, pp. 11-12.
2
5M a rtha Stevens, "A Study of the Effects of Isotonic
and Isometric Exercise on Selected Physiological Variables,"
unpublished master 1 s thesis, Department of Physical Education,
University of Korth Carolina, Greensboro, North Carolina,
1965, p. 48.
30
©zeroise.
?'b
Whlpp and Phillips"" studied the effects of a
fatiguing treadmill-walk and an Isometric leg exercise to
exhaustion.
The increase in heart rate was significantly
greater in the isotonic exercise.
Oxygen consumption was
only about half as great during the isometric exercise.
Pain was experienced in the latter part of the isometric
exercise, which may have resulted in stopping the exercise
and partially accounted for the lower heart rate and oxygen
consumption.
Lind and McNicol^ discovered that when two separate
limbs perform simultaneous isometric exercises at differentintensities, blood flow will be greater to the one with the
weaker Intensity.
When an isotonic and isometric exercise
is performed simultaneously, blood flow will be greater to
the limb performing isotonically.
Polkow and others^
discovered that the muscles have a pumping action during
heavy isotonic exercise.
Blood flows out of the muscle
'' Brian J. Whipp and Earl E. Phillips, "Cardiopulmonary
and Metabolic Responses to Sustained Isometric Exercise,"
Archives of Physical Medicine and Rehabilitation, LI (July,
1970), 399-401."
2?
A. R. Lind and G. W. McNicol, "Circulatory Responses
to Sustained Hand-Grip Contractions Performed During Other
Exercise, Both Rhythmic and Static," Journal of Physiology.
CXCII (October, 1967), 595pO
B. P. Polkow, P. Gaskell, and B. A. Waaler, "Blood
Flow Through Limb Muscles During Heavy Rhythmic Exercise,"
Acta Physlologlca Scandinavia, LXXX (September, 1970), 65.
1 ; :; J :
V '' ' ^
•
'•
31
during contraction and. flows in during relaxation.
This
muscle pump may result in an increased flow through the
muscle even when the vessels have already been maximally
dilated.
Lind and MoNicol^ found that the cardiovascular
system responds to the tension created in an isometric
exercise, not the size of the muscle group.
When two limbs
were contracted simultaneously with different loads, the
cardiovascular response was the same as for the greater
load alone.
The preceding review indicates that isotonic exercise
results in greater heart rate'responses than isometric
exercises.
Blood Pressure During Isotonic and
Isometric Exercises
Heavy resistance isotonic and. isometric type exercises
have become very popular among the general public.
Since
this rise in popularity, researchers have become concerned
with the dangers of these exercises.
has received particular attention.
The Valsalva maneuver
The Valsalva maneuver
is an increase in arterial blood pressure which results
from an increase in inter thoracic pressure.
2
The increase
9Lind and McJMicol, "Circulatory Responses to Sustained
Hand Grip Contractions," p. 595; Lind and McNicol, "Cardiovascular Responses to Holding and Carrying Weights by Hand
and by Shoulder Harness," Journai of Applied Physiology.
XXV (September, 1968}, 65-66.
32
in inter thoracic pressure is caused by "breath holding or
attempting to exhale against a closed glcttls.30
In an editorial, B r e a l ^ expressed a fear of the dangers
of isotonic and isometric exercises.
He states that iso-
metrics result in great blood pressure increases because
of peripheral resistance.
This could be serious for the
individual with a cardiac weakness.
Lind32 criticized the
recommendation of isometric exercise particularly for
persons with heart disease.
He states that little or no
increase in cardiac output will occur, and this will result
from the increase in heart rate.
The Valsalva maneuver is
considered so dangerous that a group of hypertensive men
taking part in an interval jogging research study were
instructed to avoid holding their b r e a t h . 3 3
Jackson-^ had
a group of subjects, which included persons with heart
disease, grip a'hand dynamometer isometrically.
Fifty-
seven per cent of those with heart disease were discovered
3°Phillip Bard, Medical Physiology (St. Louis, 1956),
pp. 217-218.
. S. Breal, "Risks of Weight Lifting," Journal of
the American Medical Association, CCXII (June ,~1970)", 2267*
3 2 A. R. Lind, "Cardiovascular Responses to Static
Exercise (Isometrics, Anyone?)," Circulation, XIL (February,
1970, ?'+.
"
33John L. Boyer and Fred W» Kosch, "Exercise Therapy
in Hypertensive Men," Journal of the American Medical
Association. CCXI (March7""l970T, lE&9~.
"
3^David. H. Jackson, "Isometric (Dynamometer) Stress
Testing in Coronary Heart Disease," Alabama Journal 'of
Medical Science, VII (July, 1970), 310-3127
'by an abnormal electrocardiograph reading or chest pain.
Individuals with no heart disease had no such characteristics.
Following is a review of literature which will
compare blood pressure during isotonic and isometric exercises.
Murray and Karpovitch^ noted that measurements
immediately after isotonic weight lifting show that systolic blood pressure always increases.
Diastolic blood
pressure may remain the same, rise slightly, or fall
slightly.
Brouha and Redford^ agree with this in writing
that during exercise, systolic and pulse blood pressure
always increase with the work load and diastolic blood
pressure changes are insignificant.
As will be shown in the
following review, blood pressure responses will be dependent
upon the duration of the exercise whether the exercise is
isotonic or isometric.
37
Thompson
found that a one-minute ride on the bicycle
ergometer caused the systolic blood pressure to rise
sharply for more than a minute, but there was not a significant change in diastolic blood pressure.
Both systolic
35ji m Murray and Peter V. Karpovitch, Weight Training
In Athletics (Englewocd Cliffs, 1956), p. 5 £7 ~
~ *"*
^ B r o u h a and Redford, op. cit., p. 188.
3?Clem W. Thompson, "Some Physiological Effects of
Isometric and Isotonic Work in Man," Research Quarterly
XXV (December, 1954), 481-4-82,
—
—
and diastolic blood pressure increased significantly after
a one-minute maximum Isometric effort on the grip dynamometer.
Tuttle and Horvath-
found in a similar study that
systolic pressure increased significantly in both forms
of exercise, while isotonic exercise resulted in a greater
'increase.
pressure.
They found no significant change in diastolic
K i n g m i n g h a e ^
completed a study using a wall
pulley with approximately half the weight that the subject
could raise by elbow flexion.
For the isotonic exercise,
fifteen repetitions of elbow flexion and extension were
performed.
For isometric exercise, the weight was held
at the raid-way position of elbow flexion for one minute.
Both exercises resulted in a significant rise in systolic
blood pressure, which returned to normal one minute
after exercise.
The diastolic blood pressure rose sig-
nificantly and had not returned to normal after one minute,
as a result of the isometric exercise.
During Isotonic
exercise, diastolic blood pressure rose significantly,
but returned to normal by the end of exercise.
A second
significant rise had occurred thirty seconds after
3 w . w. Tuttle and Steven M, Horvath, "Comparison of
Effects of Static and Dynamic Work on Blood Pressure and
Heart Rate," Journal of Applied Physiology., X (March,
195?) . 295-2967""""
39
Prahantha Kingminghae, "Static and Concentric Muscle
Contraction: Effect on Blood Pressure and Pulse Rate,"
unpublished master's thesis, Department of Physical
Education, University of Iowa, Iowa City, Iowa, 1963,
pp. 91 11) and 18.
3;:
ejcercise.
Bartles and others*10 found that systolic blood
pressure rose from about 1?,6 am. Hg. at rest to about 148
mm. Hg. immediately after an isometric exercise.
Diastolic
blood pressure decreased slightly as a result of the IsoAj,]
metric exercise.
Contrary to these findings, Sharkey
found that diastolic blood pressure increased in both
isotonic and isometric excr-ciaes performed at three intensities.
Systolic blood pressure also increased in both
exercises at all three intensities.
There were greater
increases in both systolic and diastolic blood pressure for
the isotonic exercises at the' two heaviest work loads.
The
isometric exercise resulted in slightly greater systolic
and diastolic blood pressures during the isometric exercise,
The findings by Sharkey^ may be explained by Lind
and McNicol.^
At a tension of 10 per cent of the maximum
voluntary contraction, a steady state is reached and
cardiovascular responses will become stable.
At tensions
of 20 and 50 per cent of the maximum voluntary contraction,
the cardiovascular responses will rise to a much higher
level and finally level off until exhaustion occurs.
^'°Bartles and others, ojd. cit. , p. 440.
^Sharkey, op. cit., pp. 526-52?.
^ 2 Ibid., pp. 526-527.
^ L i n d and KcNicol , ''Muscular Factors Which Determine
the Cardiovascular Responses to Sustained and Rhythmic
Exercise," Canadian Medical Association Journal, XVIC
(March, 196?)7"?07."
"""""
•'
36
Exhaustion occurs sooner during the stronger isometric
contraction because of occlusion of the blood vessels
resulting from the contraction.
In a later article, Lind
and McNicol^ state that Isotonic exercise usually results
in a rise in systolic blood pressure and a decrease in
diastolic blood pressure.
Isometrlc exercise results in a
large rise in both systolic and diastolic blood pressures.
Whipp and Phillips^ found that systolic blood pressure
increased to 199 tnm. Hg. for a fatiguing treadmill walk
and 196 mm. Hg. for an isometric exercise to exhaustion.
The diastolic pressure was 65'mm. Hg. during the treadmill
•walk and 132 mm. Hg. during the isometric exercise.
From the preceding review of literature, it is apparent
that systolic blood pressure always increases in both
isotonic and isometric exercises.
Diastolic blood pressure
depends on the intensity and duration of the exercise.
Lh.
Lind and McNlcol, "Cardiovascular Responses to
Holding and Carrying Weights by Hand and by Shoulder Harness," Journal of Applied Physiology, XXV (September, 1968),
261-262.
5Whipp and Phillips, ojj. cit., p. ^G3»
CHAPTEB III
PROCEDURES FOR COLLECTING DATA
. .
The procedures followed in collecting the data are
"described in detail in this chapter.
Measurements taken
were strength, oxygen consumption, heart rate, blood
pressure, and physical work capacity.
Measurements
Strength Measurement
Strength was measured on the same bench which was used
for the isotonic and isometric exercises.
The bench was
designed, to exercise the quadriceps muscle group by knee
extension.
The back rest was slanted at a 135-degree angle
and a cotton web belt was used to stabilize the subject at
the hips.
The bench had an arm rest on each side and the
seat and back were covered with a soft sponge cushion.
Adjustments could be made for upper leg length by sliding
the bench top backwards and adding an extra slat of wood
to the front of the seat.
This adjustment allowed for
three variations of one-half inch units.
The seat was
adjusted to prevent the upper leg from extending over the
bench.
The bench was designed so that the subject's lower
legs would hang from the bench when he was seated.
37
The
ankles could be placed under the bar, •which held the weight
to be lifted.
The bar ?ias -welded to two pieces of angle
iron which were suspended from rotating Joints at the top
of the bench.
One-half inch adjustments could be .made for
lower leg length.
Adjustments v.ere made so that the bar
rested directly in the bend of the ankle.
The bar was
padded with soft sponge rubber and towels to prevent pain
to the. ankle during lifting.
Strength was measured as the maximum amount of weight
which the subject could lift one time.
This was determined
by the method employed by Berger and Karris.^
started by lifting a light weight.
The subject
Ten pounds were added
after each lift until the load became difficult.
Then five
pounds were added each time until the subject could not
complete the lift successfully.
The subject was allowed to
attempt the lift;• whenever he felt that he was rested and
ready.
No special attempt was made to motivate the subject.
The range of motion was from a knee angle of 90 degrees to
a knee angle of 180 degrees.
The subject was instructed to
lift the weight with a slow, smooth movement through the
range of motion, tohen the subject could not complete the
lift as instructed, the prior weight lifted w&.? recorded
as his strength.
"Richard A. Berger and Michael W. Harris, Jl jiff acts of
Various Repetitive Rates in Weight Training- on Improvements
in Strength and Endurance," Journal for the Association for
Physical and Mental Rehabilitation» XX (November~.Dece-mbert
196bT, 2 0 5 ™
39
Oxygen Consumption Measurement
9
Cooper" states that oxygen cost Is the best means
available for equating work.
Oxygen consumption was
measured by the use of an Oxygen Consumption Computer (Model
occ 1000 - 10/60), manufactured by Technology Versatromics,
Incorporated, Yellow Springs, Ohio.
The procedures for
operating the Oxygen Consumption Computer are as follows:
1.
Plug the power cord into a 110-volt socket.
2.
Turn on-off switch on and allow thirty minutes to
warm up.
3.
Set the calibrate dial at 5*0.
Be sure the mask
and hose assembly is disconnected from the transducer.
4.
Turn the selector switch to the fan position and
leave it there for five minutes.
5.
Turn the selector switch to the cal position and
leave it there for one minute.
6.
Adjust the calibrate dial until the pointer
coincides with the cal mark on the meter face.
7.
Turn the selector switch to the check position
and push the reset button.
The pointer will move all the
way to zero on the dial, and after a one-minute automatically timed period, the hold light will come on.
The
pointer should indicate plus or minus one division,
verifying normal operation.
O
Kenneth H. Cooper, ''Quantifying Physical Activity-*
How and iMhy?" The Journal of the South Carolina Medical
Association, LXV, Sup7 1 to i:o7 12™(December, ~19 5*9 77 39•
£j.Q
8.
Fit the mask assembly tightly on. the subject's head,
9.
Connect the hose to the transducer.
Allow five
minutes for the subject to become accust med to the mask
assembly before collecting data.
10.
Turn the lo-hl switch to lo.
11.
To measure oxygen for an automatically timed
one-minute period, turn the selector switch to auto.
12.
Push the reset button and after seven seconds,
the integrate light will come on indicating that oxygen
consumption is being measured.
13.
After one minute, the -hold light will come on and
the standard cubic centimeters of oxygen consumed may be
read directly from the meter face.
1^.
To measure oxygen consumption for a longer period
of time, turn the selector switch to the man position.
15.
Push the reset button to return the pointer to
zero.
16.
Push the integrate button and oxygen consumption
will be monitored immediately.
17.
When the pointer reaches full scale, it will fall
back to zero and continue to monitor oxygen consumption.
18.
At the end of the desired time period, push the
hold button.
19.
The standard cubic centimeters of oxygen consumed
will be the value shown on the meter face plus the amount
of the full-scale readings.
41
The oxygen cost of the isotonic, and Isometric exercises
was computed as the oxygen consumed during exercise and recovery minus the resting oxygen consumption for the same
period of time.3
Heart Rate Measurement
Heart rate was monitored by a desk model physiograph
(DMP-^A) with a curvilinear amplifier (CA-2Q0) and a preamplifier , manufactured by Karco Bio-Systems, Incorporated
of Houston, Texas.
The procedures for operating the equip-
ment are as follows:
1.
Be sure all switches are off.
2.
Connect the ground wire.
3•
Plug the power cord into a 110-volt socket.
4.
Check paper and ink supply and prime needles.
5.
Turn master switch on for five minutes of warm up.
6.
Connect the preamplifier to the channel amplifier.
7.
Connect the extension cable to the preamplifier:
8.
a.
The large black wire connects to the ground.
b.
The small black wire connects to the positive.
c.
The white wire connects to the negative.
Connect the surface electrodes to the extension
cable:
^Donald K. Mathews and Edward L. Fox, The Physiological
Basis of Physical Education ana Athletics (Philadelphia,
1971), p. 41; Lawrence E. Morehouse and Augustus T. Miller,
Physiology of Exercise (St. Louis, 1963), p. 181.
42
a.
The green wire connects to the ground.
b.
The small black wire connects to the positive,
or number one.
c.
The large black wire connects to the negative,
or number two.
9.
Attach the surface electrodes to the chest:
a.
Attach the green wire (ground) to the sternum.
b.
Attach the small black wire (positive) one
inch above the nipple.
c.
Attach the black wire (negative) over the
fifth rib,
10.
Prepare for application of the electrodes as
follows:
a.
Shave and clean the skin thoroughly with
alcohol.
b.
Tear off one adhesive washer and peel off one
protective cover.
c.
Attach the adhesive side to the electrode.
d.
Fill the electrode with cream, leaving no air
pockets.
e.
Wipe off all of the excess cream.
f.
Remove the remaining protective cover.
g.
Press the electrode into place.
1.1. Set the channel amplifier on-off switch on for one
minute of warm up. '
i'i-3
12.
Set the channel amplifier ready-record switch to
record for one minute of warm tap.
13.
Set the preamplifier ready-record switch to record,
14.
Adjust the magnitude of the needle deflection with
the amplitude knob on the preamplifier.
15-
Adjust the pen position with the position knob on
the channel amplifier.
16.
Set the paper speed at .25 centimeters per second.
17.
Turn on the paper roller and heart beats will be
recorded by needle deflections on the graph paper.
Resting and recovery heart beats were counted for a
fifteen-second period of time and multiplied by four to
provide values for one minute.
Exercise heart beats were
counted for the twenty seconds of exercise and multiplied by
three to provide minute values.
To compute the heart rate
cost of each exercise, the total heart beats starting with
exercise and continuing through two minutes of recovery were
counted.
The heart beats for an equal period of rest were
subtracted from this value.
This was the heart rate cost of
h,
the exercises.
Blood Pressure Measurement
Blood pressure was recorded on the physiograph simultaneously with heart rate.
The procedures for warm up of the
^Herbert A. deVries, PhEslolojrv of Exercise for Physical
Education and Athletics (Dubuque, i960 J, p. 757
"
™~*
i?4
physiograph ars the same as described for heart rate measurement .
The blood pressure was measured by an electrosphygmorao-
noraeter linear-core (ESG-300)»
The procedures for operating
the equipment are as follows:
1.
Connect the preamplifier to the channel amplifier.
2.
Connect the cuff and cuff pump to the preamplifier.
3.
Place the cuff on the subject's right arm, placing
the microphone along the brachial artery.
4.
Turn all the switches to record.
5«
Turn the pressure and sound amplitude to zero.
6.
Centralize the pen with the position knob on the
channel amplifier.
7•
This will be the' reading baseline.
Depress 100 mm, Hg. button on the preamplifier and
adjust the pressure amplitude knob so the needle will rise
four small squares and fall back to the reading baseline.
Each small square will be equal to 25 mm. Hg..
8.
Position pen four small squares below the reading
baseline.
9.
Inflate the cuff to bring the needle back to the
reading baseline.
10.
Position the needle up four more small squares.
11.
Release the cuff pressure and the needle should
drop back to the reading baseline.
12.
Pump the cuff up to 100 mm, Hg. and adjust the
sound amplitude knob until it deflects, then release the
pressure.
45
13•
Inflate the cuff to 1^0 mm. tfg. to take the resting
blood pressure.
14.
Release the cuff pressure at a rate vjhioh will
result In the needle making a straight diagonal line to the
reading "baseline.
15.
As the needle moves downward, it will make several
deflections.
The first deflection will be systolic blood
pressure and the last will be diastolic blood pressure.
Blood pressure was measured at rest, immediately after
exercise, and during every fifteen seconds of recovery for
two minutes after exercise.
To determine the blood pressures
from the graph paper, a clear plastic ruler was placed over
the paper.
This ruler was marked so that each small square
was divided into five parts.
was recorded to the nearest
Therefore, blood pressure
5
-TJII.
Hg..
Blood pressure
could not be measured during exercise because of the sensitivity of the electrosphygrnomonometer to the sounds of movement
created during exercise.
Fulse blood pressure was computed
by subtracting diastolic blood pressure from systolic blood
pressure.
The systolic, diastolic, and pulse blood pressure
cost of each exercise was computed by adding each of the
eight recovery blood pressures and subtracting eight times
the resting blood pressure from this total.
k-6
Physical Viork Capac 1 ty Measurement
Physical •work capacity •was determined, by the Astrand
test for predicting maximal oxygen \iptake.5
This test has
been shown to be an effective determiner of physical
6
fitness.
The Monark bicycle ergometer was used in administering
the test.
The procedures for administering the test are
as follows:
1.
The seat height should be adjusted so that the
subject's toes will be directly below the knee when his
foot is in place with the pedal at the bottom of its cycle.
2.
The subject starts to ride the bicycle ergometer
with no work load.
3•
The rate is held at fifty pedal turns per minute.
This rate is maintained by keeping the speedometer on
twenty kilometers.
4.
The braking resistance is gradually increased to
two kiloponds over a period of thirty seconds.
Each kilo-
pond of braking resistance is equal to 300 kilopond meters
per minute of work.
Therefore, the test started with a
600-kilopond-meter-per~minute work load.
^P. 0. Astrand, Er^ometry-Test of Physical Fitness,
Varberg, Sweden, Monark-Crescent AB.
^P. 0. Astrand and Bengt Saltin, "Maximal Oxygen Uptake
and Heart Rate in Various Types of Muscular Activity,"
Journal of Applied Physiology, XVI (June, 1961), 977-981;
P. 0. Astrand and Irma Rhyming, "A tomogram for Calculation
of Aerobic Capacity from Pulse Rate During Submaxlmal Work,"
Journal of Applied Physiology, VII (September, 195^), 218-222.
fi. ' After each six-minute period of time the work load
was increased by one kilopond, or 300 kilopond-meters per
minute, provided the heart rate had not stabilized at 130
or more beats per minute.
To be considered stable, the
heart rate must not vary more than five beats In two consecutive minutes.
6.
Heart beats are counted on the graph paper for the
last fifteen seconds of each minute and multiplied by four
to provide minute values.
7.
The test is completed when the heart rate stabilised
at 130 beats or more per minute.^
Q
The Astrand0 test manual was followed to predict the
subject's scores.
The scores are expressed in maximum
millimeters of oxygen uptake per kilogram of body weight per
minute.
The procedures for computing the scores are as
follows:
1.
Use the mean heart rate of the last two minutes of
the test and the work load to find the maximal oxygen uptake
in liters per minute in Table 3» page 2k.
2.
Use the body weight and the maximal oxygen uptake
in liters per minute to find the maximum millimeters of
oxygen uptake per kilogram of body weight per minute in
Tables 5& and 5b •
^Astrand, Ergometrv-Test.
8
Ibld.
'4-8
3.
If more than one work load is used, the score Is the
isean of the scores for all work loads.
Pilot Study
Purpose
The review of literature shows chat a need exists to
compare isotonic and isometric work loads which are equal in
physiological work.
The purpose of this pilot study was to
equalize the amount of isotonic and isometric work performed
by measuring oxygen consumption.
Description of Subjects
Permission was obtained from the North Texas State
University physical education department to use thirty-four
male students, enrolled in a 9 : 00 A.M. track and volleyball
class during the spring of 19?2, as subjects for the study.
Three subjects did not complete the study.
One had a leg
injury, one dropped the class, and the other had a beard
which prevented the breathing mask from fitting his face*
Thirty-one subjects completed the study.
The mean age,
height, and weight were 20-73 years, 70»^1 inches, and
160.18 pounds respectively.
All testing was administered
in the physiology of exercise laboratory at North Texas
State University between 8:00 A.M. and 11:00 A.M.
Collection of Data
The pilot study required each subject to make two
visits to the laboratory.
On the first day of the pilot
4.9
study, the subject's age, height, and weight were recorded.
The strength test "was administered, as described previously.
The subject was instructed in laboratory procedures and
allowed to practice the isotonic and the isometric exercises.
On the second day, the subject performed an isotonic
exercise and three isometric exercises.
The isotonic
exercise was performed with a weight equal to 60 per cent
of the subject's strength.
Because the weight could be
adjusted only in five-pound units, the exercise loads were
always adjusted to the nearest five pounds.
The ten iso-
tonic repetitions were performed at the rate of one complete
repetition every two seconds, which were paced by a metronome.
The metronome was set to beat once each second.
The subject
was instructed to raise the weight on one beat and lower
it on the next beat.
The range of movement was from a knee
angle of 90 degrees to a knee angle of 180 degrees.
The
exercise was started on a verbal signal and stopped at the
end of ten repetitions.
The isometric exercise was started by a verbal signal
and ended by a verbal signal after twenty seconds.
The
weight was resting on a stand which required the subject
to extend his knees to approximately 1^5 degrees to lift the
weight from the stand.
On the starting signal, the subject
placed his ankles against the bar and raised the weight
about an inch from the stand.
The Isometric exercise was
;
\
50
performed with ?0, 80, and 90 per cent of the subject's
strength.
All four exercises were performed In random order
on the same day,
All possible combinations of order were
written on separate slips of paper and placed in a box.
One slip of paper was drawn for each subject and was returned
to the box after it was drawn each time.
The percentages
of strength used as the work loads in the Isometric exercises
were based on preliminary experimentation with three subjects
who were not involved in the pilot study.
On the basis of
data collected on these three subjects, it was assumed that
the oxygen cost of the isotonic exercise would be no
different from one of the three isometric exercises.
The oxygen cost of each exercise was the oxygen consumption starting with exercise and continuing through
recovery minus the resting o?:ygen consumption.
oxygen consumption was measured for one minute.
Resting
Exercise
oxygen consumption was measured starting with exercise and
continuing for four minutes after exercise.
was followed for all four exercises.
This procedure
The one-minute resting
oxygen consumption was multiplied by ^33 per cent to provide
a resting oxygen consumption value for the same period of
time as the twenty seconds of exercise plus the four minutes
of recovery.
This value was subtracted from the exercise
and recovery oxygen consumption to find the oxygen cost
of the exercise.
s
-'- f""'"
•
'!
51
Analysis of Data
The data were analysed by the Korth Texas State University Computer Center.
Q
A simple analysis of variance 'was
If)
applied to the data,''
Duncan's
range test was applied
to determine which isometric exercise was most similar to
the isotonic exercise in oxygen consumption.
The .05 level
of significance was selected to reject the null hypotheses
in all cases.
Findings and Discussion
The analysis presented in Table I shows that a significant difference existed between at least two of the
means.
data.
Therefore, Duncan's range test was applied to the
The oxygen coat values were rounded to the nearest
cubic centimeters of oxygen.
The data presented in Table II, page 53. indicates the
oxygen cost of the isotonic exercise was not significantly
different from the oxygen cost of the isometric exercise
with a resistance load of 80 and 90 per cent of the strength.
There was a mean difference of only 13.13 cubic centimeters
of oxygen between the isotonic exercise and the isometric
exercise when 90 per cent of the strength was used as a
resistance load.
Therefore, it was concluded that the
^John T. Roseoe, Fundamental Research Statistics
(New York, 1969) , p. 2.43.
""
~~
— 10
B . J. Winer, Statistical Principles in fixperlmental
Design (New York, 1962) , p. 86. * "
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53
isotonic exercise was equal in oxygen cost to the isometric
exercise with 90 per cent of the strength.
These two
exercises were employed to compare heart rate and blood
pressure in the main study.
Oxygen cost was also compared
again.
CUBIC CENTIMETERS OF OXYGEN COST AND STATISTICAL
COMPARISON OF THE ISOTONIC AND THE
ISOMETRIC EXERCISES
N-=31
Mean
Duncan's
Difference
from Isotonic Range
Test
Exercise
Per Cent
of Maximum
Strength
Mean
Isotonic 60%
655.^5
35^-9?
Isometric 70%
^85-90
253•88
169.55
Isometric
558.87
267.23
96.58
123.58
Isometric
668.58
331.2^
13.13
123.58
Standard
Deviation
130.07*
*Signifleant at the .05 level<
As shown in Table II, the standard deviations were
extremely large, indicating that the oxygen cost varied
greatly.
These large standard deviations were likely due
to resting oxygen consumption being measured for only one
minute.
The value was affected by how soon the subject
breathed after the rest period started and before it stopped.
" *' 'T -*-n']
s ~ x.
54
It was common for subjects to consume twenty to thirty cubic
centimeters of oxygen per breath.
If the measurement period
was started immediately before the subject breathed, It
could include one more breath than if it started immediately
after the subject breathed.
This would result in a great
difference when the value was converted to that for four
minutes and twenty seconds.
Therefore, it was theorized
that measuring oxygen consumption for a five-minute period
of time would result in a reduction in the amount of
variation shown in Table I.
Collection of Data
Subjects
The subjects for this study were thirty-two male
students enrolled in required physical education classes
at North Texas State University during the first summer
session of 1972.
To prevent selection of a biased group
of subjectsf classes were selected which were involved in
three diff erent activities at three different time periods *
Originally thirty-five subjects were to participate in the
study, but three were excluded because of a malfunction of
the research equipment.
Twelve subjects were enrolled in a
7:30 A.M. tennis class, nine were enrolled in a
10 A.M.
beginning swimming class, and eleven were enrolled in a
10:50 A.M. weight training class.
The mean age, height,
and weight of the subjects were 22.78 years, 69.50 inches.
53
and 163.96 pounds-
The mean strength for the group *as~
218.75 pounds with a .standard deviation of 5 0 . 3 0 pounds,
Each of the three physical education classes was
•visited.
The study was briefly described, and the importance
of following the test schedule was emphasized.
Each student
filled out a card with his name, address, phone number,
instructor's name, and morning free period.
The next day
each student and instructor was given a copy of the testing
schedule.
The instructors were cooperative in encouraging
the subjects to be present at their .scheduled time.
A
post card was mailed to each subject so that he would
receive it the day before he was scheduled for testing.
The subject was reminded of his test date.
He was instructed
to refrain from consuming food or beverage or using tobacco
for one hour prior to the test, and to avoid any vigorous
exercise prior to the test.
Only one subject was absent
for his scheduled testing; therefore, he was tested at a
later date.
All testing was administered between ?iJQ A.M. and
12:30 A.M. in the physiology of exercise laboratory at North
Texas State University.
This study required each subject
to make two visits to the laboratory.
On the first day,
the subject's age, height, and weight were recorded.
His
strength was measured as described previously in the pilot
* f
>o
study.
Each subject was instructed in laboratory and testing
procedures and «as allowed to practice the exercises.
On the second day at the laboratory, the subject rested
on the bench for a minimum of five minutes prior to being
hooked up for testing.
tional five minutes.
No data were collected for an addi-
The order of performing the isotonic
and the Isometric exercises was randomized by tossing a
coin for each subject.
Heads was designated as the iso-
tonic exercise being performed first, and tails was
designated as the isometric exercise being performed first.
Twenty of the thirty-two subjects performed the isometric
exercise first«
Oxygen consumption, heart rate, and blood pressure
were monitored simultaneously.
Oxygen consumption was
monitored by an assistant for a five-minute rest period
before each exercise, and a five-minute exercise period
which started with each exercise.
A stop watch which was
accurate to a tenth of a second, was used to time the periods.
Heart rate and blood pressure were monitored by the investigator.
Instructions for performing the isotonic exercise
were as follows;'
1.
You are to complete ten repetitions of the Isotonic
exercise, straightening the knees completely and lowering
the bar completely on each repetition.
2.
Make the movement as smooth as possible.
57
3-
The metronome is set to beat once each second.
Time the repetitions so that you will lift the bar
on one beat and lower it on the next.
5»
Listen for a while and try to get the pattern in
mind.
6.
On the signal "ready," place your ankles against
the bar.
?•
On the signal "begin," start the exercise.
8.
Be sure that you do exactly ten repetitions.
9.
When you have completed the ten repetitions, stop
and relax as completely as possible.
Instructions for performing the Isometric exercise
were as follows:
1. You are to perform the isometric exercise for
twenty seconds.
2.
On the signal "ready," place your ankles against
the bar.
3.
On the signal "begin," lift the bar just enough
to clear the stand and hold it for twenty seconds.
k.
On the signal "stop," lower the bar to the stand
immediately and relax as completely as possible.
After the subject performed the isotonic and the
isometric exercises, the work capacity test was administered.
This completed the testing.
s8
Procedures for Analysis of Data
At the conclusion of data collection. the data were
statistically analyzed by the Korth Texas State University
Computer Center.
The .05 level was arbitrarily selected
to reject the null hypotheses.
Hypotheses one through
three were tested by a single and two-factor analysis of
variance for repeated measures.•^
When a significant
change occurred in the cardiovascular responses to the
isotonic and. to the isometric exercise, Duncan's multiple
12
range test was applied to the data to locate this change.
When the cardiovascular responses were found to be different
as a result of the two exercises, Duncan's range test
was applied to the mean changes to determine where the
differences occurred.
13
according to Kirk.
This analysis was computed "by hand
Hypothesis four was tested by a
t - t e s t H y p o t h e s e s five and six were tested by the
Pearson product-moment
correlation."^
Hypothesis seven was
to be tested by a t-test for differences between correlatlon
coefficients.
However, only one significant correlation
1 •]
Roscoe , OJD. clfc.
12
Winer, o£. clt.
Roger E. Kirk, Experimental Design; Procedures for the
Behavioral Sciences (Belmont, California, 1 9 ^ 7 , pp. 93~9^«
15
Jbld., p. 75'
"^David H. Clarke and H. Harrison Clarke, Research in
Physical Education, Recreation, and Health (Englewood^ClXffs,
1970), pp.~"235-:2T"
' ' "f •"1 <? * V
59
-coefficient was found in hypotheses five and six.
Hence
there was no justification for statistically analyzing
hypothesis seven.
CHAPTER IV
PRESENTATION OF DATA
Findings of the Study
"
Data collected for this study included oxygen cost
of the isotonic and the isometric exercises; heart rate and
blood pressure at rest, during exercise, and recovery from
exercise; and the work capacity test.
Results of the oxygen consumption measurements are
presented in Table III.
V/ith a mean net oxygen difference
of only 12.50 cubic centimeters between the isotonic and
the isometric exercises, no significant difference was
found.
The standard deviations were not reduced in mag-
nitude by monitoring oxygen consumption for a five-minute
period of time, as theorized in the pilot study.
The
oxygen cost of the exercises was considerably higher in
the pilot study.
This may have occurred because the
subjects in the pilot study performed four exercises, compared with two exercises in the main study.
Recovery may
not have been complete after the exercises, which would
have resulted in a higher oxygen consumption during the
next exercise.
Even though this difference occurred between
the two studies, the mean differences between the isotonic
exercise and the Isometric exercise were almost identical,
60
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with the -isotonic exercise having a slightly greater net
oxygen cost in both studies.
Results of the hypotheses tests and the presentation
of data follow:
1.
Isotonic exercise will result in no significant
change in the following variables:
a.
heart rate during exercise and during each
fifteen seconds of recovery for two minutes after
exercise.
This hypothesis was rejected.
Figure 1 indicates
that heart rate rose sharply during exercise and returned
to normal rapidly after exercise.
Further analysis pre-
sented in Table IV shows that there was a significant
TABLE IV
ANALYSIS OF VARIANCE FOR HEART RATS MEASUREMENTS DURING
ISOTONIC AND ISOMETRIC EXERCISE AND RECOVERY
Source
Degrees
of
freedom
Sum of
Squares
Mean
Squares
F
Probability
2,569.57
59.49
0.00
Blocks
31
79,656.81
Treatments
19
99,505-2?
9
99,075.38
11,008.38
254.86
0.00
1
86.29
86.29
2.00
0.16
9
589
343.60
25,441.28
38.18
43.19
0.88
0.54
639
204,603.36
A(Rows-"=Time)
B(Columns™
Exercise
AB(Interaction
Residual
Total
63
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64
finding in the rovs.
This indicates? that the exercise did
result in a significant change in heart rate and is employed
as the basis for rejecting the hypothesis.
Duncan's range
test was applied to the data to determine "when the changes
occurred.
Results of the test are presented In Table V.
TABLE ¥
HEART BATES DURING ISOTONIC
EXERCISE AND RECOVERY
N-32
Isotonic
Mean
10.84
109-47
13.36
3.83*
:15
•99.56
15.93
3.79*
OO
83.63
13.14
3.75*
:45
77.75
11.22
3.71*
1:00
76.50
12.47
3 • 66*
1:1.5
75.63
11.73
3 »59
1:30
75.13
11.79
3.51
1:45
74.75
12.13
3.39
2:00
73.75
12.10
3-22
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•^Significant at the .05 level
65
The heart rate rose significantly during exercise and remained
significantly high during the first minute of recovery.
In
Table IV the significance found in blocks indicates that the
subjects differed from each other, cr blocking was appropriate.
b.
systolic blood pressure during each fifteen
seconds of recovery for two minutes after exercise.
This hypothesls was rejected.
Figure 2 indicates that
systolic blood pressure rose sharply as a result of isotonic
exercise and returned to normal rapidly during recovery.
Further analysis presented in Table VI shows a significant
finding in the rows—that is, systolic blood pressure did
TABLE VI
ANALYSIS OF VARIANCE FOR SYSTOLIC BLOOD PRESSURE DURING
ISOTONIC AND ISOMETRIC EXERCISE AND RECOVERY
Degrees
of
Freedom
Sum of
Squares
Blocks
31
110,566.08
Treatments
17
22,820.22
8
Source
A(Rows-Time)
B(Columns=
Exercise)
AB(Interaction
Residual
Total
Mean
Squares
F
Probability
3,566.65
27.30
0.00
20,738.13
2,592.27
19.84
0,00
1
540.56
54-0.56
4.14
0.04
8
52 ?
1,5^1.53
68,849.67
192.69
130.64
1,47
0.16
575
202,235.97
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in fact change significantly as a result of isotonic exercise.
This finding was the basis for rejecting the hypothesis.
Duncan*s range test kqs applied to the data to locate the
significant changes.
The results are reported in Table VII.
The exercise resulted in the systolic blood pressure being
significantly increased for one minute and fifteen seconds
TABLE VII
SYSTOLIC BLOOD PRESSURE AT REST AND DURING
RECOVERY FROM ISOTONIC EXERCISE
N=32
T
Mean
Isotonic
Standard
Deviation
t
104.69
11.70
:15
129.06
26.71
6.95*
:30
125.63
22.75
6.93*
11?,50
17-04
6.83*
1:00
115.94
17.01
6.80s
1:15
112.34
13.91
6.60*
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1:30
109.69
16.21
6.36
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111.41
15.62
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110,78
15.09
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68
after exercise.
After returning to normal, it again
increased, significantly after one minute and forty-five
seconds.
The significance found for blocks in Table VI
indicates that the subjects were different from each other,
or blocking was appropriate.
c.
diastolic blood pressure during each fifteen
seconds of recovery for two minutes after exercise.
This hypothesis was rejected.
Figure 3 indicates that
a change did occur in diastolic b].ood pressure as a result
of Isotonic exercise.
Further analysis presented in Table
VIII shows that a significant difference did occur in the
TABLE VIII
ANALYSIS OF VARIANCE FOR DIASTOLIC BLOOD PRESSURE DURING
ISOTONIC AND ISOMETRIC EXERCISE AND RECOVERY
Degrees
of
Freedom
Sum of
Squares
Blocks
31
28,380.56
Treatments
17
2,465.45
8
1,377.17
•172.15
3.51
0.00
1
166.84
166.84
3.41
0.07
8
921.kk
115.18
2.36
0.02
Source
A(Rows=Time)
B(Columns=
Exercise)
A3(Interaefcion)
Residual
52?
Total
25.817.88
56.663.89
575
Mean
Squares
915.50
48.99
Probability
I8.69
0.00
69
Isot
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rows, or diastolic blood pressure did In fact change as a
result of isotonic exercise.
rejecting the hypothesis.
This finding was the basis for
Duncan's range test v:as applied
to the data to locate the changes.
presented in Table IX.
Results of the test are
The isotonic exercise resulted In no
significant change in diastolic blood pressure during the
first fifteen seconds of recovery.
There was a significant
TABLE IX
DIASTOLIC BLOOD PRESSURE AT REST AND DURING RECOVERY
FROM ISOTONIC EXERCISE
N=32
Mean
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62.19
8.42
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62.34
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58.28
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:45
6l. 56
8.08
3.43
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62,66
9.07
3-82
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61.40
10.02
3.61
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62.19
9.91
3.43
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62.50
11.07
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60.16
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3.73
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"^Significant at the *05 level ,
3-61
71
decrease thirty seconds after exercise and no significant
change from rest during the last one minute and thirty
seconds of recovery.
The significance found for the blocks
in Table VIII indicates that the subjects were different
from each other, or blocking was appropriate.
d.
pulse pressure during each fifteen seconds of
recovery for two minutes after exercise.
This hypothesis "was rejected.
Figure 4 indicates that
pulse pressure did rise as a result of isotonic exercise.
Further analysis presented in Table X shows a significant
finding In the rows.
This indicates that pulse pressure
TABLE X
ANALYSIS OF VARIANCE FOR PULSE PRESSURE DURING ISOTONIC
AND ISOMETRIC EXERCISE AND RECOVERY
Degrees
of
Freedom
Sum of
Squares
Mean
Squares
F
Probability
Blocks
31
88,732.64
2,862.34
20.02
0.00
Treatments
17
33-357.12
8
31.197.74
3.899.72
27.27
0.00
1
1,406.25
1,406.25
9.83
0.00
8
527
753.13
75.359.55
94.14
143.00
0.66
0.73
575
197M9.31
Source
A(Rows=Tlme)
B (Columns-'
Exercise)
AB(Interaction
Residual
Total
72
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73
did change significant'
exercise.
Luring recovery from isotonic
This 'was th3 basis for rejecting the hypotheses.
Duncan's range test vo.s applied, to the data to determine
where the changes occurred.,
sented in Table XI.
Results of the test are pre-
There was a significant increase in
TABLE XI
PULSE PRESSURE AT REST AM) DURING RECOVERY
FROM ISOTONIC EXERCISE
N-32
:=:™SE=I~S=:rt==:=:=:=:=:n=;^=Tr.=..'SKrr^
Mean
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67.97
22.61
7.28*
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16.28
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53-28
16.44-
7.11*
1:15
52.19
12.95
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^Significant at the .05 level.
"
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pulse pressure Immediately after exercise 'which persisted
for one minute and fifteen seconds.
The pressure had
again reached a significantly high level by the end of
two minutes of recovery.
The significance found for the
"blocks in Table X Indicates that the subjects were different , or blocking was appropriate.
2.
Isometric exercise will result in no significant
change in the following variables:
a.
heart rate during exercise and during each
fifteen seconds of recovery for two minuses after
exercise.
This hypothesis was rejected.
Figure 1, page 63.
indicates that the heart rate rose sharply during exercise
and returned to normal rapd11y after exercise.
The data
in Table IV, page 62, show that a significant difference
was found in the rows.
This indicates that the exercise
did result in a significant change in heart rats.
was the basis for rejecting the hypothesis.
This
Duncan's
range test was applied to the data to determine when the
changes occurred.
The results are reported in Table XII.
The heart rate rose significantly during exercise, and
remained significantly high for the first forty-five
seconds of recovery.
75
TABLE XII
HEART HATES DURING ISOMETRIC
EXERCISE AKB RECOVERY
Mean
Isometric
"standard
Deviation
~
t
—
Rest
73.31
10.72
112.19
15.76
3.83*
: 15
102.13
17.21
3.79*
* 30
86.25
12.69
3. 75*
:45
78.63
12.39
3.71*
rt m
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1:00
75.63
12.04
3,66
1:15
7^.25
13.05
3-39
Tj
1:30
74,75
12.99
3.59
1:45
74.00
13.17
"5
2:00
74.63
13.58
3.51
Exercise
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^Significant at the .05 level.
b.
systolic blood pressure during each fifteen
seconds of recovery for two minutes after exercise.
This hypothesis was rejected.
Figure 2, page 66,
Indicates that systolic blood pressure did rise as a result
of the exercise.
Further analysis presented in Table VI,
page 65, shows a significant difference In the rows, which
76
indicates that isometric exercise did in fact result In a
significant change in the syctolic blood pressure»
finding was the basis for rejecting the hypothesis.,
This
Duncan's
range test was applied to the data to determine when the
changes occurred.
The results are reported in Table XIII.
The systolic blood pressure was significantly higher during
TABLE XIII
SYSTOLIC BLOOD PRESSURE AT REST AND DURING
RECOVERY FROM ISOMETRIC EXERCISE
N=32
Mean
Isometric
Standard
Deviation
109.06
13.29
: 15
122.19
26.49
6.75*
:
30
119.22
23.39
6.71*
:45
115.00
19-84
6.45
1:00
115,22
16.44
6.53
1:15
113.28
15.27
6.36
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1:30
108.?5
12.89
5.60
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1:45
108.59
13.98
6.00
2:00
108.28
15.II
6.10
Rest
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^Significant at the .05 level,
the first thirty seconds of recovery.
significant difference was found.
After that time, no
? ? •
o»
diastolic blood pressure during each fifteen
seconds of recovery for two .minutes after exercise.
This hypothesis was rejected.
Figure 3, page 69# indi-
cates that diastolic blood pressure did change and followed
an irregular pattern.
Further analyses presented in Table
VIII, page 68, show that a significant difference was found
in the rows.
This indicates that a change aid in fact occur.
The hypothesis was rejected- on the 'basis of
this finding.
Duncan's range test was applied to the data to determine •when
the change occurred.
The findings reported in Table XIV show
TABLE XIV
DIASTOLIC BLOOD PRESSURE AT REST ARD D'JRIl-SG
RECOVERY FROM ISOMETRIC EXERCISE
li-32
Isometric
Standard .
Deviation
Mean
Rest
:15
:
60
30
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65.31
8.13
57-3^
11.00
^.00*
59.53
10.50
3.95*
63-75
9.33
3.61
62.66
9.92
3.82
65.31
9.24
3.^3
6k.06
10.12
3.^3
62.03
10.23
3.89
j0.15
. 3.73
62,97
1
^Significant at the .05 level.
?8
that isometric exercise resulted in a significant increase in
diastolic blood pressure during the first thirty seconds of
recovery.
After this time, no significant difference was
found.
d.
pulse pressure during each fifteen seconds of
recovery for two minutes after exercise.
This hypothesis was rejected.
Figure ^, page ?2, shows
that the pulse pressure increased during Isometric exercise.
Further analysis presented in Table X, page ?1, shows a
significant finding in the rows.
This indicates that pulse
pressure did, in fact, change significantly.
was rejected on this basis.
Duncan's range test was applied
to determine when the changes occurred.
reported in Table XV.
The hypothesis
The results are
Pulse pressure was significantly
increased during the first miniate of recovery from isometric
exercise.
3.
After this time, no significant change was found.
There will be no significant difference in the
mean change in the following variables resulting from
isotonic and isometric exercises which have been equalized:
a.
heart rate during exercise and during each
fifteen seconds of recovery for two minutes after
exercise.
This hypothesis was accepted.
Figure 1 indicates that
the heart rate response was almost identical for the two
exercises employed.
Table IV shows a non-significant
79
TABLE XV
PULSE PRESSURE AT BEST AND DURING BECOVEBY
FROM ISOMETRIC EXERCISE
N'~32
Mean
44.38
14.41
:15
65,00
24.03
7.19*
: 30
60.31
21.17
7.15*
:4 5
52.81
17.96
7 • CZ*
1:00
51 >41
16.03
6.90*
1:15
47.66
13.25
6*65
1:30
45.00
13.07
5.86
1:^5
46.88
14.41
6.38
2:00
45-31
15.3^
6.17
Rest
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Isometric
Standard
Deviation
''Significant at zne .05 level,
finding for the columns, which indicates that the heart rate
response was the same for each exerciseb.
sj/rtolie blood pressure during each fifteen
seconds of recovery for two minutes after exercise.
This hypothesis was rejected.
Figure 2 indicates
that systolic blood pressure rose more as a result of
isotonic exercise.
The sign.ificance in the columns of
VI reveals that a difference did occur between the responses
to the two exercises,
Duncan's range test was applied to
the data to determine when the differences occurred. The
data in Table XVI show that the mean increase In systolic
blood pressure was-significantly greater for isotonic exercise during the first forty-five seconds and the last thirty
seconds of the two-mlnu.te recovery period.
TABLE XVI
SYSTOLIC BLOOD PRESSURE CHANGES DURING RECOVERY PROM
ISOTONIC AND ISOMETRIC EXERCISES
N=32
--r--
Isotonic
Standard™
Mean Deviation
•p
£
•H W
s d
fl
CO
<H O
h 0)
_
0)
O <5
o
<S>
Difference
Stan3.*ar3"
Mean Deviation
24.38
22.21
13.13
22.99
11.2
20.60
• 30 20.94
19.86
10'. 1 6
17.89
10.78*
20.08
:45
12.81
15.02
5.94
13-53
6.88*
17.40
1:00
11.25
14.54
6.16
13.06
5.09
19.94
1:15
7-66
13.44
4.22
14.37
3.44
21.53
1:30
5.00
15.35
-0.31
10.77
5.31
18.92
1:45
6.79
13.24
-0.47
11,87
7.19*
I8.96
2:00
6.09
I.1!!!.
78
10.78
6.88*
I8.39
:15
m
<o
I some trie
Stan<TarcC~"
Wean Deviation
^Significant at the -05 level.
tl
c.
diastolic. b3 ood pressure during each fifteen
seconds of recovery for two minutes after exercise.
This hypothesis was rejected.
Figure 3 shows that the
diastolic blood pressure response was somewhat similar but
followed an irregular pattern.
This was shown to be true
by the significant interaction displayed in Table VIII.
Results of Duncan's range test, presented in Table XVIIF
show that isotonic and isometric exercises produced significantly different changes in diastolic blood pressure during
TABLE XVII
DIASTOLIC BLOOD PRESSURE CHANGES DURING RECOVERY
FROM ISOTONIC AImD ISOMETRIC EXERCISES
>S5
N=32
Isotonic
Standard
Mean Deviation
0.16
30
- 3 * 90
45
£ rq
•H 'J 5
f."* 1 00
6
rt a1 15
m
10.89
Difference
Standard
Mean Devi at ioi
-7.97
11.35
8.13*
14.80
8,20
-5.78
10.86
1.86
13.24
-0.63
7.16
-3 . 5 6
9.11
0.94
11.67
0.4?
8.74
1 -.P. .65
9.84
3«13
11.05
-0 c 7 8
9-68
0.00
3.80
0.78
13.14
0.00
8.33
-1.25
O
•
,£r
O
15
Isometric
Standard
Mean |
[Deviation
3.25
12.38
1 4.5
0.31
9-75
-3.28
8.29
3.59
11.30
2 00
- 2 . 0 3
-2.34
9«
0.31
13.67
Q
•P
r
U
d 1 30
<
>D &£
O
o
CD
«
9.06
I
^Significant at the *05 level•
12
the first fifteen seconds of recovery-
Diastolic blood pres-
sure was significantly lovier as a result of isometric
exercise.
No other significant differences were found to
exist between the exercises.
d.
___
pulse pressure during each fifteen seconds of
recovery for two minutes after exercise.
This hypothesis was rejected.
Figure !i Indicates that
pulse pressure was higher as a result of isotonic exercise.
The signlflcance shown for the columns in Table X indicates
that the response was different for the two forms of
exercise.
Duncan's range test was applied to the data to
determine when the response to the two exercises differed.
The results presented in Table XVIII shew that the isotonic
exercise resulted in a significantly greater increase
thirty seconds after exercise.
No other significant dif-
ferences were revealed.
4.
There will be no significant difference in the
following changes resulting from isotonic and Isometric
exercises:
a.
the total change in heart beats starting Kith
exercise and continuing for two minutes after exercise.
This hypothesis was accepted.
Results of the t-test
presented In Table XIX, page 8k, show that no significant
difference, exists between the total change In heart beats
for the two modes of exercise.
on this basis.
The hypothesis was accepted
TABLE XVI.II
PULSE PRESSURE- CHANGES DURING RECOVERY FROM
ISOTONIC Ai\D ISO'fciETRIC EXERCISES
32
Isotonic
Standard
Mean Deviatior:
m
0
•<p
Difference
Standard
Mean Devi at lor.
Standard
Deviation
23.75
23.14
20.63
19.12
3.13
23,20
: 30 24.22
2.1.52
15.94
17.85
8.28*
22.49
15.06
8.44
15.68
3.28
18.52
13.16
7.03
17.41
2.50
20,20
12.73
3.28
14.73
5.16
21.83
17.46
0.63
13.^9
3.13
21.20
15
:45 11.72
•
a <0
Q r; 0
S ^ 1:00
7 * JJ
CO
O
8.44
•H 0 1 : 1 5
CO
1: 30 3.75
$
Recovery
and
Isometric
1:45
4.69
14.36
2.50
12.31
2.19
18.49
2:00
7.03
12,69
0,94
13.35
6.09
18.91
•^Significant at the .05 level,
b.
the total change in eight systolic blood
pressure measurements during two minutes of recovery
from exercise.
This hypothesis was rejected.
The data in Table XIX
show that the total of the systolic blood pressure responses
was significantly greater for the isotonic exercise.
was the basis for rejecting the hypothesis.
This
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c.
the total change in eight diastolic blood
pressure measurements during two minutes of recovery
from exercise.
This hypothesis was accepted.
The results reported in
Table XIX show that the total diastolic "blood pressure
response was no different as a result of either exercise.
The hypothesis was accepted on this basis,
d.
the total change in eight pulse pressure
measurements during two minutes of recovery from exercise. ,
This hypothesis was accepted.
The results of the t-test
presented in Table XIX indicate that' there was no significant
difference in the total response to thy two forms of exercise.
This was the basis for accepting the hypothesis.
5.
There will be no significant correlations between
physical work capacity and the following changes resulting
from isotonic exercise:
a.
the total change in heart beats starting with
exercise and continuing for two minutes after exercise.
This hypothesis was accepted,
b.
the total change in eight systolic blood
pressure measurements during two minutes of recovery
from exercise.
This hypothesis was accepted.
8c
c * the total change in eight diastolic blood
pressure measurements during two minutes of recovery
from exercise.
This hypothesis was accepted.
d.
_
the total change in eight pulse pressure
measurements during two minutes of recovery from
exercise.
This hypothesis was accepted.
All of the above were accepted on the basis of the
analysis presented in Table XX.
Physical work capacity
was found to have no significant correlation with any of the
four cardiovascular responses to isotonic exercise«
6,
There will be no significant correlations between
physical work capacity and the following changes resulting
from isometric exercise:
a.
the total change in neart- beats starting with
exeicise (iiiG confc.inu.ing for two minutes aft s r exercise•
This hypothesis was accepted.
Data presented in Table
XX show that no significant correlation was found between
physical work capacity and the total heart rate response.
b.
the total change In eight systolic blood
pressuie ineasureznents during two minutes of recovery
from exercise.
This hypothesis was rejected.
The data in Table XX
show that a low "but significant correlation coefficient was
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88
found between physical work capacity and systolic blood
pressure.
However, this was too low to have predictive value.
c.
the total change in eight diastolic blood
pressure measurements during two minutes of recovery
from exercise.
This hypothesis was accepted.
Results shown in Table XX
reveal that no significant correlation coefficient was found
between physical work capacity and diastolic bloci pressure.
d.
the total change in eight pulse pressure
measurements during two .minutes of recovery from exercise.
This; hypothesis 'was accepted.
Data presented in Table
XX show that no significant correlation coefficient was
found between physical work capacity and pulse pressure.
The findings contained in Table XVI, page 80, indicate
that only one significant correlation coefficient was found
between physical work capacity and the various measures of
cardiovascular cost.
test hypothesis
7.
Therefore, it was not necessary to
seven, which was stated as follows?
There will be no significant differences in the
correlations between physical work capacity and the following changes resulting from isotonic and isometric exercises:
a.
the total change in heart beats starting
with exercise and continuing for two minutes after
exercise,
89
b.
the total change in sight systolic blood
pressure measurements during two minutes of recovery
from exercise,
c.
the total change In. eight diastolic blood
pressure measurements during two minutes of recovery
from exercise>
d.
the total change in eight pulse pressure
measurements during two minutes of recovery from
exercise.
Summary and Discussion
The findings of this study indicate that when an equal
amount of energy was spent in performing an isotonic and an
isometric exercise, the heart rate responses were the same.
This finding is in disagreement with most of the literature
reviewed.
In most studies, heart rate
found to be
4
higher as a result of isotonic exercise.
Heart rate
increased significantly as a result of both exercises.
Brian J. Sharkey, "A P.n3T>iological Comparison of
Static and Phasic Exercise," Research Quarterly» XXXVII
(December, 1966), 530; Floyd Lawrence hall, "Heart-Rate
Relative to Isometric and Isotonic Kusole Contraction,"
unpublished master's thesis, Department of Physical Education, University of Iowa, Iona City, Iowa, 1962, pp. 11-12;
J• A. C. Knox, "The Effect of the Static and of the Dynamic
Components of Muscular Effort on the heart Rate,'' Journal
of Physiology, CXII3 (March, 1951), 3?~39; Brian j7"whlpp
and Earl E. Phillips, 'Cardiopulmonary and Metabolic
Responses to Sustained Isometric Exercise,41 Archives of.
Physical Medicine and Rehabilitation, LI (July, 1970), 3994oi. '
—
—- — _
90
Resting blood pressure mis found to be lower than what
is considered normal.
Morehouse and M l l e r ^ state that a
systolic blood pressure of 120 ms, Hg., and a diastolic
blood pressure of 80 mm. Hg, is normal for young adult males.
This would provide a normal pulse pressure of 40 mm. Hg..
Findings of this study revealed resting mean systolic blood
pressures of 104.69 mm. Hg. and 109• 06 nun. Hg. and diastolic
blood pressure of 62.19 mm. Hg. and 65.31 mm. Hg., which are
considerably lower than what is considered normal.
However,
resting mean pulse pressures were 43.75 mm. Hg. and ^4„38 mm,
fs
Hg., which could be considered normal.
DeVries
states that
considerable error may occur in indirect blood pressure
measurements.
This must be taken into consideration when
interpreting these findings.
Since blood pressure compari-
sons are being made which were measured with the same Instrument , the abnormally low findings should not hinder the
interpretation of the findings.
The findings of this study differ from statements
made by Lind and McNicol."^ They stated that isotonic
tL
--Lawrence E. Morehouse and Augustus T. Miller,
Physiology of Exercise (St. Louis, 1963), p. 116.
6
Herbert A. deVries, Physiology of Exercise for
Physical Education and Athletics (Dubuque, I9S6), p. 95.
7
A. R. Lind and G. W. KoNicol, "Cardiovascular
Responses to Holding and Carrying Weights by Hand and by
Shoulder Harness," Journal of Applied Physiology, XXV
(September, 1968) , 261-2&2.
"
j«y
j
91
exercise usually results in a rise In systolic blood pressure
and a decrease in diastolic blood pressure.
Isometric
exercise results in a large rise in both systolic and diastolic
blood pressure.
The findings of this study showed a sig-
nificant rise in systolic blood pressure as a result of both
"exercises, with the response to the isotonic exercise being
significantly higher than the response to the isometric
exercise.
Diastolic blood pressure decreased significantly
as a result of both exercises.
similar findings.
Bartles and others® had
When an isometric exercise was performed,
the systolic blood pressure rose from 126 mm. Hg. to about
148 mm. Hg. immediately after exercise, while diastolic
blood pressure decreased slightly-
Findings of this study
revealed that pulse pressure rose significantly as a result
of both exercises, with the response to the isotonic and the
isometric exercises being no different.
To summarize, all four cardiovascular measurements
changed significantly as a result of the isotonic and the
isometric exercises.
The systolic blood pressure was
significantly greater for the isotonic exercise at five
measurement times.
Isometric exercise resulted in the
diastolic decreasing and showing a significant change from
the isotonic exercise at one measurement time.
_ _
—
— -
Pulse
Robert L. Bartles et al., "Effects of Isometric Work
on Heart Rate, Blood Pressure, and Oxygen Cost," Research
Quarterly, XXXIX (October, 1968), 439.
9?.
pressure increased significantly more as a result of isotonic
exercise during one measurement time*
Only the systolic
blood pressure cost was greater for the isotonic exercise.
A significant correlation coefficient was found between
physical work capacity and the systolic blood pressure cost
of isometric exercise, but it was too low to have predictive
value•
CHAPTER V
SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS
Summary :
One purpose of this study was to determine whether an
isotonic and an isometric exercise would result in a difference in cardiovascular stress,
In order to make the
two exercises comparable, the work loads were equalized on
the basis of oxygen cost.
The second purpose was to deter-
mine the relationship between cardiovascular stress resulting
from the isotonic and the isometric exercise and physical
work capacity.
A pilot study was conducted to locate an isometric work
load which would be equal in oxygen cost to a ten-repetition
isotonic exercise with 60 per cent of the maximum strength.
Subjects for this study were thirty-one college males enrolled in a required physical education class at North Texas
State IJniveristy during the spring semester of 1972.
Findings
of the study showed that there <ms no significant difference
in the oxygen cost of the isotonic exercise and an isometric
exercise performed for twenty seconds with 90 per cent of the
maximum strength.
Therefore, these two exercises were used
for comparison in the main study.
S
9^
Subjects for the main study were thirty-two college
males enrolled tu required physical education classes at
North Texas State University during the first summer session
of 1972.
Data collected for comparison of the isotonic and
the isometric exercises included heart rate, systolic blood
pressure, diastolic blood pressure, and pulse blood pressure.
Oxygen cost of the two exercises was determined in order to
verify the findings of the pilot study,
Physical work capa-
city was assessed by the Astrand test for predicting maxl«. „m
oxygen uptake.
All cardiovascular measurements and oxygen
consumption were conducted simultaneously.
The isotonic and
the isometric exercises were performed on the same day, with
the order of performance randomized.
was performed last.
The work capacity test
Heart rates and blood pressures were
recorded meohanically on graph paper by a physiograph.
Oxygen
consumption was monitored by an oxygen consumption computer.
Appropriate statistical tests were applied to the data by the
North Texas State University Computer Center.
The .05 level
of significance was selected to reject the null hypotheses
in all cases.
The following is a summary of the findings of this study»
1.
Isotonic and isometric exercises resulted in signi-
ficant Increases in heart rate during exercise and recovery
from exercise,
?•< .vV"' ,
2.
Isotonic and isometric exercises resulted in
significant increases in systolic 'blood pressure during
recovery from exercise.
3.
Isotonic and isometric exercises resulted in
significant decreases in diastolic blood pressure during
recovery from exercise.
Isotonic and isometric exercises resulted in
significant increases in pulse pressure during recovery
from exercise.
5-
There was no significant difference in heart rate
responses to isotonic and isometric exercises.
6.
Systolic "blood pressure responses to isotonic
exercise was significantly greater than responses to isometric exercise.
7.
Diastolic blood pressure decreased significantly
more as a result of isometric exercise than isotonic exercise.
8.
Pulse pressure was significantly greater as a result
of isotonic than isometric exercise.
9.
The total increase in eight systolic blood pressure
measurements during recovery from isotonic exercise was
significantly greater than for Isometric exercise.
The total
changes in heart rate, diastolic blood pressure, and pulse
pressure were not significantly different for isotonic and
isometric exercises.
10.
There was a significant positive but low relation-
ship between physical work capacity and the total increase
96
in systolic blood pressure during recovery from Isometric
exercise.
There was no significant correlation coefficient
between physical work capacity and the total Increase in
heart rate, diastolic blood pressure, or pulse pressure
resulting from isometric exorcise,
- -_1X»
There was no significant correlation coefficient
bet.v:een physical work capacity and the total increase in
heart rate, systolic and diastolic blood pressures, or
pulse pressure resulting from isotonic exercise#
Conclusions
The following conclusion," were formulated based on the
findings of this studyt
1,
Either isotonic or isometric exercise will result
in significant changes in heart rate, systolic and diastolic
blood pressures, and pulse pressure.
All four variables will
return to normal shortly after exercise.
2.
The pattern of the heart rate, systolic blood pres-
sure , and pulse pressure will be similar for the two modes of
exercise.
The pattern of the diastolic blood pressure re-
sponses are somewhat similar but Irregular.
3*
Physical work capacity is of no value in predicting
the cardiovascular stress caused, by isotonic and isometric
exercises.
Systolic blood pressure will rise significantly
higher for an isotonic exercise than for an isometric exercise,
He c o itme rtd a t i o ns
As a result of this study, the following recommendations
are offered*
1.
To determine the effects of training on cardio-
vascular stress during Isotonic and isometric exercises, it
is recommended that the same data "be collected before and
after a training program.
2.
It is recommended that an electrocardiogram be
taken for comparison while subjects are performing isotonic
and isometric exercises.
3.
it is recommended that both isotonic and isometric
exercises with resistance loads comparable to those employed
in this study should be avoided by persons with heart disease.
It is possible that the blood pressure would be of sufficient
magnitude to result in a heart attack, and the isotonic exercise would be more dangerous than the Isometric exercise,
It is recommended that commercial health studios
refrain from prescribing heavy resistance exercises for
persons of questionable health* such as the elderly and the
obese.
5.
It is recommended that physical educators do not
allow any person suspected of having a cardiovascular disease
participate in a training program which employs heavy resistance exercise,
98
6.
Isotonic and isometric exercises with resistance
loads comparable with these employed in this study are
recommended for any person who is in normal health.
Both
forms of exercise are known to result in strength increases
and may be prescribed by athletic coaches, athletic trainers,
physical therapists, and physical educators.
7.
Because of the short duration of the resistance
exercises employed in this study, they are not recommended
as a means of Increasing cardiovascular endurance, and they
are not recommended as a panacea to fitness.
L
/-,.«
5J BLIOGRAPHY
Articles
A3trand, P, 0» and Irma Phyming, "A Nomogram for Calculation
of Aerobic Capacity from Pulse Bate During Submaxliaal
Work," Journal of Aoplisd Physiology, VII (September,
195'0I 21b-222«
Astrand, P„ 0. and Bengt Saltin, "Maximal Oxygen Uptake and
Heart Hate in Various Types of Muscular Activity,"
Journal of Applied Physiology, XVI (June, 1961), 977-981.
Barties, Robert L. and others, "Effects of Isometric Work
on Heart Rate, Blood Pressure, and Oxygen Cost," Research
Quarterly, XXXIX (October, 1968), ^39.
.
Bergar, Richard A. and Michael w. Harris, "Effects of Various
Repetitive Rates in Weight Training OR Improvements in
Strength and Endurance," Journal for the Association
for Physical arid Mental Rehab Xl 11atTon~~XX; ~TNovemberLeoe mb er, "T96ZI j' 205®
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