LiS. hSSk Strength Test

A standard (6. Tiemann and Go.) leg dynasiometer was used to measure

static leg atrength. The starting position for the test was in a sitting

position with the back in a vertical position and against a wall. The

upper legs were in a position parallel to the floor. The feet were spaced

about twelve inches apart and flat on the floor. While in this position,

a leather strap was placed behind the subject's neck and secured to the

handle of the dynamooieter. The length of the dynamometer chain was

adjusted so that the proper testing position could be maintained. The

subject attempted to rise vertically keeping the back and shoulders against

the wall. The subject was instructed not to begin with a sudden jerk but

to exert a steady even force.

The subjects warmed-up by performing about twelve squats without

weights before taking the test. Two trials were given, with a thirty-

second rest between trials. The best score was recorded. To acquaint

subjects with the correct performance of the tests, two practice trials

were given two days prior to actual testing*

Dynamic Leg Strength Test

The starting position for the dynamic strength test was similar to

the starting position of the static strength test. The subject assusMd

a squatting position with the upper legs parallel to the floor and the

feet shoulder-width apart. A barbell was held behind the head, resting

on the shoulders. From this position the subject attempted to extend

the legs and attain a standing position..

Prior to actual testing, the subjects were instructed in the proper

iMthod of performing squats. The subjects were asked to determine as

10

closely as possible the greatest amount of weight they could lift one

tisM from a squatting position. Two-thirds of that amount was used as the

starting poundage for actual testing. After each successful lift, weight

was added usually in ten-pound increments. As the subject approached his

maximum lift, only five pounds were added to the bar. The subjects

rested at least two minutes between trials.

The test used to measure leg power was a modification of a leg power

test devised by Gray, Start, and Glencross (8). These investigators

determined leg power in terms of the physical principle power work/time.

This leg power test had a test-retest correlation coefficient of 0.985

and a coefficient of objectivity of 0.981. The authors concluded that

the test was valid for measuring the power of the legs developed in a

vertical jump. A modified leg power test was used in the present study

because of the difficulty in enploying the leg power test as originally

developed by Gray et al. The modified leg power test was found by Gray

et al. (9) in a later study to correlate 0.989 with the original

criterion sieasure of power. For this reason the modified leg power test

was considered acceptable for use in the present study.

The sK>dlfied leg power test was administered in the following manner.

The subject stood sideways to a jump board with the preferred arm extended

above the head and next to the bcMrd. The other arm was placed behind

the back. The height of the extended hand was marked on the board while

standing on tiptoe. Maintaining a straight back and the position of the

arms, the subject adopted a full squat position. When stationary and

balanced in this position, the subject sprang upwards and marked the

11

maximum height of the jump on the jump board by means of chalked finger-

tips. Kach jump was scored to the nearest one-quarter inch.

Two days prior to the scheduled test all subjects practiced the jump

test. Each subject was required to jump several tisies in order to warm-

up the leg muscles before being tested. Three attempts were made. The

best score was recorded.

Statistical Analysis

Static leg strength and dynamic leg strength were both related to

leg power by the Pearson product-moment correlation coefficient (6) in

order to determine whether significant relationships existed. Significant

correlation coefficients would show that static leg power and dynasdc

leg power were truly related to leg power. The degree of this relationship

would depend on the size of the coefficients. The two correlation

coefficients were then cosqjared to determine whether they differed signif1-

eantly from each other (6). A significant difference between correlation

coefficients would show that one kind of leg strength was more related

to leg power than another kind.

The coefficient of reliability for the static leg strength test was

0.95 as determined by the test-retest method based on twenty-five subjects.

At least one day intervened between test days. The coefficient of

reliability for dynaodc leg strength was not determined. However, previous

studies have shown that the coefficients of reliability for dynamic

strength tests are usually above 0.95 (3, 13, 19).

CHAPTER 1X1

PRESENTATION AND ANALYSIS OF RESULTS

This study was designed: first, to determine the relationship

between leg power and both static and dynamic leg strength; second, to

determine whether static and dynamic leg strength are similarly related

to leg power. Data were collected from sixty-six male college students

who were tested for leg power, static leg strength, and dynamic leg

strength. Correlation coefficients were then determined between leg

power and both static strength and dynamic leg strength. These two

correlation coefficients were then cosfiared to determine whether they

were significantly different.

i^SiZiJ o Results.

The correlation coefficient found in the present study between

static leg strength and leg power was .64 which was significant at the

.01 level of confidence. This relationship between static strength

and performance was in agreement with the results obtained by Harris (10).

Harris found a significant relationship between back and leg dynamometrlcal

strength and Sargent Jump, 40 yard dash, broad jump, basketball throw

for distance, three pound shot distance, twelve poimd shot distance, and

obstacle relay time. Larson (15) also found significant correlation

coefficients between four static strength tests of leg strength, left

grip strength, right grip strength, back strength and a composite motor

ability score. However, in the same study Larson found that the same

strength tests did not correlate significantly to gross body coordination.

12

13

Inalgnlfleant relationships were found by Reach (18), Henry

and Whitley (11), and Smith (21) between static strength and physical

performance tests which involved speed of movement in the first two

studies and vertical jump in the last study. Henry and Whitley and

Smith concluded that an insignificant relationship resulted because

atrength exerted against a dynamometer involves a different neuromotor

pattern from that controlling the muscles during a movement. The

results of the present study do not support this conclusion since static

strength was related significantly to power. A significant correlation

coefficient may have been obtained by Smith if he had converted the

vertical jump score in inches to power and then correlated this with

static leg strength such as was done in the present study. To investigate

this possibility, the static strength scores of subjects in this study

were related to inches junped. The correlation coefficient obtained

in this relationship was .35 which was significant at the .01 level of

confidence. This coefficient was considerably less than the .64 found

when strength was related to power and lends credence to the supposition

examined.

With the exception of the results found by Smith (21), tests that

required substantial strength to perform appeared to relate higher to

static strength than tests which required little strength to perform.

When gross body coordination (15) and speed of oiovement (11) were related

to strength, insignificant eorrelations were found. However, when

strength was related to a composite motor ability test, which required

substantially more strength to perform, the relationship was significant.

vi-

14

A correlation coefficient of .71, which was significant at the

.01 level, was found between dynodc leg strength and leg power. This

relationship was in agreement with the results obtained in previous

studies by Lerson (14, 15) who found significant correlation coefficients

between dynamic strength tests of dips, chinning, and vertical jump and

a composite siotor ability test.

The eorrelation coefficients of ,64 and .71 found between leg

power and static leg strength and dynamic leg strength, respectively,

were analysed to determine whether they were significantly different (6).

Although dynamic strength appeared to be more highly related to power

than static strength, the two coefficients of .64 and .71 were not

found to be signifleantly different. Static leg strength was considered

to be as highly related to leg power as was dynamic leg strength. These

results were not supported by Larson (14) who found by factor analysis

techniques that dynamic strength was more related to motor ability

than was static strength.

The difference between results obtained in this study and Larson's

study may have been due to the criterion to which static strength was

related. In the present study both measures of strength were related

to a single power test whereas Larson related strength to a conposlte

motor ability score. This score consisted of not only power but several

other components cooprising oiotor ability such as agility, coordination,

strength, speed, and endurance. It may be assumed that strength related

signifleantly more to power than most of these components of motor

ability since an Increase in strength or force will theoretically result

in an Increase in power provided other factors are held constant. This

15

will not necessarily occxir with motor ability components of agility,

coordination, speed, and endurance.

Although there was not significant difference In the relaticrshlp

of static and dynamic strength to power, this would not indicate that

static strength can be predicted with high accuracy from dynamic

strength or vice versa. This was shown by the correlation coefficient

of .60 found between static leg strength and dynamic leg strength

which meant that the accuracy of prediction was only thirty-five per

cent. This correlation coefficient was similar to the coefficients

obtained by Richards (20) and Berger (2) which were .67 and .70,

respectively.

CHAPTER IV

SUMMARY AND CONCLUSIONS

Sumsmry

The purpose of this study wass first, to determine whether leg

power was significantly related to static leg strength and also to

dynamic leg strength; and second, to determine if static leg strength

or dynamic leg strength was more related to leg power than the other.

Data were obtained from sixty-six male college students at Texas

Technological College. Each subject was measured for leg power, static

leg strength and dynamic leg strength. The strength tests were

measured with the subject in a sqtiat position. Correlation coefficients

were detersdned between leg power and both static and dynasdc leg

strength. The two correlation coefficients were then compared to

detersdne whether they were significantly different from each other.

The correlation coefficients obtained between leg power and static leg

strength and dynasdc leg strength were .64 and .71, respectively, both

significant at the .01 level. The two coefficients were not significantly

different from each other.

Conclusions

Based on the results of this study the following conclusions were

drawnt

1. There is a significantly high relationship between leg power

and static and dynamic leg strength.

2. Neither static leg strength nor dynamic leg strength is more

related to leg power than the other.

16

LIST OF REFERENCES

1. Baer, Adrian D., et al. "Effect of Various Exercise Progrsms on Isometric Tension, Endurance and Reaction Time in the Human." ArchlYJg al Physical Medicine QJ^^ Rehabilitation 36:445-502 August, 1955.

2. Berger, Richard A. "The Effects of Selected Progressive Resistance Exercise Programs on Strength, Hypertrophy and Strength Decrement." Unpublished Master's Thesis, Michigan State University, 1956.

3. Berger, Richard A. "Determination of the Resistance Load for 1-RM and 10-MI." Journal of the Association for Physical and Mental Rehabilltatien 15:108-10; July-August, 1961.

4. Berger, Richard A. "The Effects of Dynamic and Static Training on Vertical Jumping Ability." Material to be Published in the MfifiAil Q^ay

18

13. Jones, Robert E. "Reliability of the Ten Repetition Maximum for Assessing Progressive Resistance Exercise." Journal of the American EtoAsal aflBX Affyftgftt Q 42:661-62; October, 1962.

14. Larson, L. A. "A Factor and Validity Analysis of Strength Variables and Tests with a lest Combination of Chinning, Dipping, and Vertical Jump." Research Quarterly 11:82-96, December, 1940.

15. Larson, L, A. "A Factor Analysis of Motor Ability Variables and Tests, with Tests for College Men." Research Quarterly 12:49^-517^ October, 1941.

16. Meadows, Paul. The Effects of Isotonic and Isometric Muscle Contraction Training on Speed. Force. and Strenf tt . Unpublished Doctoral Thesis, The University of Illinois, Urbane, 1959.

17. Rarick, Lawrence. "An Analysis of the Speed Factor in Simple Athletic Activities." Research Quarterly 8:89-105; December, 1937.

18. Rasch, Philip J. "Reletioxiship of Arm Strength, Weight, and Length to Speed of Arm Movement." Research Quarterly 25:328-32; October, 1954.

19. Reuter, Edward Richard. The Relationship of Weight Lifting Performance tff Certain Measures of Body Structure. Unpublished Doctoral Thesis, The University of Illinois, Urbana, 1957.

20. Richards, Bertram Donald. A Comparison o^ Cable Tenslometer Strength. llM* 5E^ lO-RM Values Obtained la Knee Extension. Unpublished Master^s Thesis, Michigan State University, 1955.

21. Smith, Leon R. "Relationship Between Explosive Leg Strength and Performance in the Vertical Jump." Research Quarterly 32.405-8, October, 1961.

Subject Number

1 2 3 4 S 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Dynasdc Test Pounds

239 205 255 275 185 185 255 225 205 215 275 215 205 235 255 275 335 240 185 250 240 220 280 215 205 185 265 205 195 175 300 245 235 285 245 135 205 195 190 305

APPENDIX

Raw Test

Static Test Pounds

230 310 235 390 250 215 200 230 210 350 330 250 280 255 255 330 310 230 135 190 265 200 355 190 240 195 345 230 240 155 330 240 345 375 245 185 200 230 235 295

Scores

Power Foot Pounds

206,3 196.8 233.7 263.2 123.7 151,8 173.7 180.0 176,5 225.5 252.0 150.0 181.2 174.1 193.5 217.5 237.8 213.3 152.3 180.2 234.8 170.5 198.0 164.3 150.8 235.0 202.9 190.0 150.5 160.1 276.7 192.8 237.5 160.3 129.8 132.1 163.5 202.8 210.8 165.0

Vertical Jump Inches

16 1/2 12 1/2 15 17 3/4 11 13 1/2 15 11 1/4 13 16 1/2 18 12 1/2 12 1/2 11 18 14 1/2 16 1/2 16 13 1/4 12 1/2 13 3/4 15 1/2 12 1/4 12 1/4 12 3/4 13 12 3/4 14 3/4 10 1/2 13 1/4 20 1/2 13 15 13 10 3/4 13 13 13 3/4 13 1/4 8 1/4

Body Wt. Pounds

150 189 187 178 135 135 139 192 163 164 168 144 174 190 129 180 173 160 138 173 205 132 194 161 142 217 191 160 172 145 162 178 190 148 145 122 151 177 191 240

19

20

Subject Number

41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66

Dynasdc Test Pounds

195 235 175 185 145 195 205 170 215 175 205 170 140 145 185 155 235 205 145 160 195 295 215 135 135 235

Static Test Pounds

265 185 250 250 265 190 220 250 210 150 280 285 225 195 265 150 270 235 250 220 255 310 250 190 230 260

Power Foot Pounds

170.0 198.1 152.3 156.7 189.1 166.2 143.7 122.7 159.5 157.1 135.0 226.5 165.0 140.0 197.1 111.0 227.3 199.5 122.6 193.3 158.7 225.2 202.5 154.3 126.4 175.0

Vertical Jtnqp Inches

13 14 1/2 13 1/4 13 1/4 12 3/4 10 1/2 12 1/2 10 3/4 11 11 1/2 10 18 3/4 11 12 14 1/4 10 3/4 14 3/4 14 1/4 11 1/2 12 3/4 15 11 1/2 15 14 1/4 10 1/4 12 1/2

Body Wt Pounds

157 164 138 142 178 190 138 137 174 164 162 145 180 140 166 124 185 168 128 182 127 235 162 130 148 168