The Physiologic Effects of Isometric Work on Man

46 Pages·01.908 MB·English

by  Thompson, Clem Wheelcock

THE PHYSIOLOGIC EFFECTS OF ISOMETRIC W W ON MAN
Clem wj* Thompson
A dissertation submitted in partial fulfillment of the requirements
for the degree of Doctor of Philosophy in the Department of
Physical Education in the Graduate College of the
State University of Iowa
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ACKSOWLSIttMEENTS
Th© writer ■wishes to express his sincere appreciation to
Professor W* W. Tuttle, Department of Physiology, College of
Medicine, State University of Iowa for his direction of this thesis*
The writer wishes also to take this opportunity to admit his lack
of preparation in the subject of Calculus* In the beginning the
fact that integration of equations would be necessary was not
recognized* However, when it was found to be necessary, Professor
C» D* Janney, also of the Department of Physiology, to whom I
express appreciation, consented to make th© necessary calculations.
ill
TABLE OF CONTENTS
Pag®
Introduction f .............. 1
Technique for Measuring Maximum Strength and Strength
Endurance 2
Th© Relation of Maximum Strength to Strength
Endurance • * 20
The Effect of Isometric Work on Arterial Blood
Pressure 21*
A Comparison of th© Effect of Isometric Work and
Isotonic Work on Arterial Blood Pressure ........ . 28
Conclusions , ........ • « • • • • * ............ 31
Appendix 33
Bibliography 1*0
iv
TABUS OF FIGURES
Figure Page
1 Amplifier, grip dynamometer and recorder.
Read from left to right 3
2 Grip dynamometer for men . . . . . . . . . . .
3 Strain gauge circuit diagram for the grip
dyn&raometer ........... . . . . . . . 6
U Calibration carve for the grip dynamometer
for men .............................. 9
5> Strength record for a period of one minute made
by the Bsterline-Angus recorder. Read from
right to left................. 11
6 Element of the area (Z) used in calculating the
relation of average strength for on® minute, to
the area under th© strength curve. Read from
right to left • 13
7 Factor for correction of the area, due to
curvilinear coordinates, in th© computation of
average strength for one minute . . . . . . . . 16
V
TABLE OF TABLES
Table Pag©
I Comparison of H Calculated by Using Formula and
& Determined by Subdivision of Interval T • • • 19
II Calibration Table for Grip Strength Dynamometer
for Men , ....................... 21
III delation of Maximum Strength to Strength
Endurance.......................... 23
IV Th© Effect of One Minute of Isometric Work on
Arterial Blood Pressure • 2$
V The Mean Effect of Isometric Work on Arterial
Blood Pressure ........ 26
VI Level of Significance of Isometric Work on
Arterial Blood Pressure . » ......... . . • 27
VII Comparison of Arterial Blood Pressure Changes
Resulting from Isometric and Isotonic Work * • 29
VIII Levels of Significance of the Comparison of
Arterial Blood Pressure Change® Resulting from
Isometric and Isotonic Work 30
IX Individual Data Collected from Two Hundred
Cases Showing the Maximum Strength, Strength
Endurance and Per Cent of Strength Endurance/
Maximum Strength « . .................. 3k
1
Introduction
For the purpose of investigating the effects of isometric
work on physiologic functions, it seems logical to express the iso­
metric work in term® of strength.
The problems investigated included the relation of maximum
strength to strength endurancej th© effect of isometric work on
arterial blood pressurej and a comparison of the effects of isometric
and isotonic work on arterial blood pressure.
Strength has been measured by dynamometers of various types
since their introduction by Brigham In 1872^. In general, strength
has been measured either as contraction*^^ or breaking strength^*^
expressed as pounds or kilograms. Up to the present time the
dynamometers employed provide for measuring maximum strength only.
If one wishes to gain a complete picture of strength in man, it seems
necessary to record not only maximum strength, but also the tension
developed by a group of muscles over a period of time.
In order to provide a complete picture of the tension which
one is able to develop in a group of muscles and to provide a means
of comparing maximum strength with strength endurance, the dynamometer
described in th© following discussion was devised. In this investiga­
tion only grip strength was studied, thus only a grip dynamometer is
discussed. However, the principles employed in the grip strength
technique are equally applicable to the measurement of the strength
of almost any other muscle group.
2
Technique for Measuring Maximum Strength and Strength Endurance
General Description of the Grip Dynamometer
The grip dynamometer, amplifier, and recorder as arranged
for measuring grip strength are shown in Figure 1. The details of
th© dynamometer are shown in Figure 2. Th© subject places his hand
around the grips A and B with th© little finger against the stop C,
This insures that the hand will be in the same position on the dyna­
mometer when repeated tests are made. When th© subject squeezes,
the lower ends of th© dynamometer are pulled together, thus causing a
small bowing in the region above the fulcrum B, The bowing activates
a strain gauge (Statham Ifodel G-l) E, This arrangement is used since
the force required to actuate the gauge is much smaller than the grip
strength.
The dynamometer is mad© of tool steel with the dimensions
as shown in Figure 2, The grips A and B are made of aluminum and
are secured by screws. As described, this dynamometer provides for a
full-scale reading of 170 pounds. Other dimensions may be used to
give either larger or smaller full-scale readings, but this is
sufficiently large to measure th© grip strength of the majority of
men. Because of possible variations in the modulus of elasticity,
different dynamometers may give somewhat different full-scale readings
even though they are made to the same dimensions.
It is necessary to protect the strain gauge against movement
beyond its normal limit, which in this instance is O.OOlU in. This
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Fig. 2* Grip dynamometer for men.