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The comparative effects on vertical jump of three different depth jump programs 1978

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THE COMPARATIVE EFFECTS ON VERTICAL JUMP OF THREE DIFFERENT DEPTH JUMP PROGRAMS by Francis John Alexander Hawkins B.P.E., University of B r i t i s h Columbia, 1972 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF PHYSICAL EDUCATION i n THE FACULTY OF GRADUATE STUDIES (School of Physical Education and Recreation) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA AUGUST 1978 (c) Francis John Alexander Hawkins, 1978 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Co lumb ia , I a g ree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s tudy . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i thout my w r i t t e n p e r m i s s i o n . Department o f P h y s i c a l E d u c a t i o n and R e c r e a t i o n The U n i v e r s i t y o f B r i t i s h Co lumbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date August 31, 1978 i i ABSTRACT The purpose of this study was to investigate which factor in depth jumping, landing momentum or landing velocity, is the more effective in improving vert^- i c a l j ump. Three depth jump training conditions were utilized: a high velocity, high momentum condition in which the subjects (n=10) jumped unloaded from their individual optimum heights (the height where their rebound height equaled the height jumped from); a low velocity, high momentum condition in which the subjects (n=10) jumped wearing weight jackets that weighed 15% of their body weight from heights that resulted in their landing momenta being equal to their calculated landing momenta had they been performing the high velocity, high momentum conditions; and a medium velocity, low momentum condition in which the subjects (n=8) jumped unloaded from heights midway between their optimum heights and their calculated jump heights had they been performing the low velocity, high momentum condition. Twenty-eight male members of University of British Columbia athletic teams volunteered as subjects. Each team was divided equally between, but individual team members assigned randomly to, each of the three experimental conditions. The depth jump programs consisted of four sets of eight jumps twice a week for the f i r s t three weeks and five sets of eight jumps three times a week for the last three weeks. A l l subjects were tested at the beginning, middle and end of the study on the Sargeant Jump Test, Standard Depth Jump Test (performed from an 18 in platform). Knee Extension Strength Test and Plantar Flexion Strength Test. Multivariate analysis :of variance revealed that performance of a l l three training conditions resulted in improvement of vertical jump, standard depth jump and plantar flexion strength ( a l l significant at the .01 level) and that i i i there were no significant differences between the conditions in improvement on these measures. No significant improvement was seen in knee extension strength in any of the conditions. Pearson Product Moment Correlation of the four variables showed that there were strong correlations between sargeant jimp and standard depth jump (significant at the .01 level) and between knee extension strength and plantar flexion strength (significant at the .05 level)- but no significant correlations between the jump and strength measures. At the end of the study a force platform was ut i l i z e d to record the reaction force characteristics of eight subjects while they performed jumps under each of the three training conditions. Multivariate analysis of variance of the data revealed significant d i f f - erences between the conditions on the impulse variables and no significant differences between the conditions on time or force variables. Post-hoc Newman-Kuels multiple comparison tests revealed that the impulses of the subjects when jumping under the low velocity, high momentum condition were significantly greater (at the .05 level) than the impulses recorded when the subjects were jumping in the other two conditions (which were not significantly different from each other). The results of this study did not indicate clearly which factor in depth jumping, landing momentum or landing velocity, was more effective in improving vertical jump. i v TABLE OF CONTENTS Chapter PAGE 1. INTRODUCTION 1 STATEMENT OF THE PROBLEM 2 DEFINITIONS 2 HYPOTHESES 3 DELIMITATIONS A LIMITATIONS 5 SIGNIFICANCE OF THE STUDY 5 2. REVIEW OF LITERATURE 7 Studies on V e r t i c a l Jump 7 Depth Jumping 11 3. METHODS AND PROCEDURES 19 SUBJECTS 19 TIME AND DURATION OF THE STUDY 19 TESTS 20 Sargeant Jump Test 20 Standard Depth Jump Test 20. Cable Tensiometer Tests 21 PROCEDURES FOR THE DEPTH JUMPING PROGRAMS 21 EXPERIMENTAL DESIGN 22 STATISTICAL TREATMENT 26 TABLE OF CONTENTS Chapter Page 4. RESULTS AND DISCUSSION . 27 Results: The Effect of Depth Jump Training on Sargeant Jump, Standard Depth Jump, Knee Ex- tension Strength and Plantar Flexion Strength 27 Discussion 36 Results: Force Platform Analysis of the Three Training Conditions 40 Discussion 50 5. SUMMARY AND CONCLUSIONS 53 REFERENCES 56 APPENDICES 62 APPENDIX A: Individual Data 63 APPENDIX B: Sample Calculations 83 v i LIST OF TABLES Table Page 1. Velocities Attained In The Training Height Range 23 2. Training Heights 24 3. Observed Cell Means 28 4. Observed T r i a l Means 28 5. 3,x 3 Anova Of Sargeant Jump 31 6. Summary of Trend for Sargeant Jump 31 7. 3 x 3 Anova of Standard Depth Jump 32 8. Summary of Trend for Standard Depth Jump 32 9. 3 x 3 Anova of Knee Extension Strength 33 10. 3 x 3 Anova of Plantar Flexion Strength 33 11. Summary of Trend for Plantar Flexion Strength 34 12. Pretest Correlation Coefficients 34 13. Midtest Correlation Coefficients 35 14. Posttest Correlation Coefficients 35 15. Means of Variables 43 16. Anova of Landing Force 44 17. Anova of Jump Force 44 18. Anova of Dip Force 44 19. Anova of Total Impulse 45 20. Newman-Kuels Multiple Comparisons Test of Total Impulse 45 21. Anova of Landing Impulse 46 22. Anova of Jump Impulse 46 23. Newman-Kuels Multiple Comparison Test of Jump Impulse 47 v i i LIST OF TABLES CONTINUED Table Page 24. Anova of Half Jump Impulse 47 25. Newman-Kuels Multiple Comparisons Test of Jump Impulse 48 26. Anova of Total Time 48 27. Anova of Landing Time 49 28. Anova of Jump Time 49 29. Anova of Half Jump Time 49 v i i i LIST OF FIGURES Figure P a ge 1. Expermental Design 35 j 2. Force Platform Tracings 42 i x ACKNOWLEDGEMENTS The investigator would l i k e to express appreciation to the members of the committee for t h e i r guidance i n th i s study and to the various i n d i v i d u a l s who assis t e d i n other aspects of the study: L. Southern for advice, a s s i s t - ance and materials; T. Wood for programming guidance; R. Schutz for advice i n s t a t i s t i c s ; G. Bowbrick for construction of equipment; and to the subjects who p a r t i c i p a t e d i n the study. Chapter 1 1 INTRODUCTION Plyometrics i s a form of power t r a i n i n g (Wilt, 1975; Verhoshanskiy, 1966, 1967) which u t i l i z e s the p r i n c i p a l of prestretching the muscles to a t t a i n greater developed force and speed of contraction of those muscles (Marey, Demeny, 1885; Cavagna, Dusman, Margaria, 1968; Thys, Faraggiana, Margaria, 1972). The e f f e c t i s a summation of forces caused by storage of energy i n the muscles' seri e s e l a s t i c component and by the a b i l i t y of the c o n t r a c t i l e element to develop a greater force a f t e r being stretched (Cavagna, Dusman, Margaria, 1968). More force i s developed when the muscle i s stretched f a s t e r , when the muscle i s stretched to a greater length and when the p o s i t i v e work follows more quickly a f t e r the s t r e t c h , (Cavagna, Dusman, Margaria, 1968; Asmussen, Bonde-Petersen, 1974; Wilt, 1975) . I t has been found that the greater forces developed by prestretching muscle r e s u l t i n a t r a i n i n g e f f e c t whereby the muscle gains strength and the nerve-muscle apparatus becomes more rea c t i v e with r e s u l t i n g increase i n power (Verhoshanskiy, 1966, 1967). Depth jumping i s a plyometric exercise which has been developed to increase leg power and as such may be of value to most ath l e t e s . I t has been recommended that depth jumps be performed with resistance not i n the form of weights but as an increase i n the height from which the jump i s made. Ranges have been found for maximum increase i n reactive a b i l i t y and strength and these are 0.75 m and 1.15 m res p e c t i v e l y (Verhoshanskiy, 1967). Beyond the upper l i m i t damage i s done to the jumping s k i l l and no p o s i t i v e t r a i n i n g e f f e c t i s seen (Verhoshanskiy, 1967, W i l t , 1976). There does not appear to have been any i n v e s t i g a t i o n into the e f f e c t s of loading during depth jumping although i t has been stated that overloading i s an undesirable a c t i v i t y 2 (Verhoshanskiy, 1967). STATEMENT OF THE PROBLEM The purpose of the i n v e s t i g a t i o n i s to compare the e f f e c t s of three depth jumping programs on a v e r t i c a l jump. DEFINITIONS Plyometric Exercise - an a c t i v i t y which increases power s t r e t c h i n g the mus- cles immediately p r i o r to contraction. Depth Jump - a plyometric exercise which emphasizes an explosive take-off a f t e r landing from a previous drop. Depth jumping i s believed to improve the reactive a b i l i t y of the nerve-muscle apparatus. Loading - the mass of the subject plus any external mass acting on the sub- j e c t . Amortisation:Phase:'- i s the part of the depth jump where the legs are slowing the descending body mass. Po s i t i v e Work - done when the muscles are shortening i n length. Negative Work - done when the muscle r e s i s t s while being stretched. Eccentric Contraction - when the muscle i s t r y i n g to shorten while being stretched. Negative work i s done. Concentric Contraction - when the muscle i s shortening during contraction. Isometric Contraction - when the muscle i s t r y i n g to shorten but i s held at a constant length. I s o k i n e t i c Contraction - when the muscle i s contracting c o n c e n t r i c a l l y but . at a constant speed. Voluntary Contraction - the response of a muscle to a stimulus evoked by a conscious decision of the i n d i v i d u a l . 3 Reflex Contraction - the response of a muscle to a stimulus evoked by a nerve path through the spinal cord. There is no conscious control over the reflex. Myotatic Reflex - the response of an innervated muscle to stretch. A stretch reflex. Elastic Recoil - when the series-elastic components of the muscle, after being stretched, release their stored energy by shortening. Counter-movement - a preparatory movement in the direction opposite to that of the f i n a l movement. Optimum Height - where the height of the rebound jump equals the height jumped from. Optimum height can also be found by determining from which height the time on the ground is minimum with the amortisation phase taking the same amount of time as the rebound phase. A l l these things occur during a jump from optimum height. HYPOTHESES Depth jump training w i l l produce a significant increase in jumping ab i l i t y . Rationale; Since performance of the vertical jump and depth jump re- quire leg power an increase in leg power as a result of depth jump training should result in an increase in vertical jump. Depth jump training w i l l produce a significant increase in leg strength. Rationale: Since depth jump training improves leg strength there should be resultant increases on the leg strength tests. The low velocity, high momentum group w i l l produce a significant leg strength increase over the two other groups. Rationale: Depth jump training increases leg muscle strength and the 2. low velocity, high momentum (overload) group w i l l be jumping with great- er relative mass than the two unloaded groups and so w i l l have a greater resistance to work against in the rebound phase. This should cause a larger increase in static leg strength. 4. The high velocity, high momentum group w i l l produce a significant . increase in jumping a b i l i t y over the medium velocity, low momentum group which w i l l produce a significant increase^ in jumping ab i l i t y over the low velocity, high momentum group. Rationale: Depth jump training develops increased power by apparently increasing the reactive a b i l i t y of the nerve-muscle apparatus. It has been discovered that more force is developed in the muscle i f the z stretch is faster and the positive contraction occurs immediately following the eccentric contraction. This may be the factor that im- proves reactive a b i l i t y . The high velocity, high momentum group jumping from optimum height w i l l attain the greatest velocity and w i l l spend the least time on the ground so should be able to jump higher than the other groups. The medium velocity, low momentum group jumping from sub- optimum height w i l l attain a greater velocity than the low velocity, high momentum group and should improve their reactive a b i l i t y to a higher level, the result being more jumping a b i l i t y . DELIMITATIONS 1. The subjects for this study w i l l be members of University of British Columbia men's athletic teams. 2. The effects of the depth jumping programs w i l l be assessed over a six week period. 3. The effects of the depth jump programs w i l l be measured by the Sargeant Jump Test, a Standard Depth Jump Test and cable tensiometer tests of 5 Knee Extension and Plantar Flexion Strength. LIMITATIONS 1. The investigator w i l l have no control over the subjects' a c t i v i t i e s outside the testing s t i t u a t i o n . 2. The subjects w i l l not n e c e s s a r i l y have the same number of p r a c t i c e hours per week at t h e i r respective sports. 3. Motivation of the subjects to provide maximum e f f o r t i n the program w i l l not be able to be assessed. 4. In testing, the height of the v e r t i c a l jumps w i l l be a measure of hand displacement and therefore not a completely true measure of centre of gravity displacement. SIGNIFICANCE OF THE STUDY Depth jump t r a i n i n g i s b e n e f i c i a l i n developing leg power and does so by u t i l i z i n g muscle stre t c h p r i o r to p o s i t i v e muscle contraction. The act of prestretching the muscle i s believed to allow greater forces of contraction through momentary storage of energy i n the muscle's seri e s e l a s t i c elements and increased force of contraction by the muscle's c o n t r a c t i l e elements. P h y s i o l o g i c a l studies have determined that muscle forces are affected by the v e l o c i t y of the s t r e t c h , that i s the faster the s t r e t c h the greater the muscle force created. I t has been discovered that there i s an optimum jump height where maximum reactive a b i l i t y i s developed and beyond which dynamic strength i s increased but reactiveness decreases. The reason for this seems to be that the momentum of the drop becomes too great for the muscles to d i s - sipate and the switch to p o s i t i v e work occurs too slowly to aid i n increasing reactive a b i l i t y . There are, however, no published studies i n v e s t i g a t i n g the e f f e c t s of overloading during depth jumping. Overloading changes the 6 quality of the jump by increasing momentum i f the drop i s the same distance as for an unloaded jump. If the momentum is to be kept the same as in the unloaded jump the velocity must be decreased by decreasing the height of the drop. This study w i l l attempt to establish which one of the factors, momen- tum or velocity, is predominant in enhancing jumping a b i l i t y . Chapter 2 REVIEW OF LITERATURE There have been many studies reported on the effect.of training programs on vertical jump, but few on the effects of depth jumping on vertical jump. There have been, to the investigators knowledge, only two sc i e n t i f i c studies (Keohane, 1977'; Scoles, 1978) completed on depth jump training and another that reported the effects of bounding on running speed. There have been sev- eral articles, mostly empirical, that dealt, with depth jumping but they did no offer evidence of a completed training study. Therefore, s c i e n t i f i c ..training studies that have had vertical jump as a parameter w i l l be examined. Studies on Vertical Jump Studies that have used vertical jump as a parameter are legion and have utilized many different methods of training. Programs have been followed using weight training, isometric exercise, isokinetic exercise, isotonic exercise, jumping exercise, rope jumping, stair running and trampolining. Capen (1950), Garth (1954), Ness and Sharos (1956), Brown and Riley (1957), Knudtson (1957), Chui (1960), Luitjens (1969), Darling (1970), Tanner (1971), Staheli, Roundy and Allsen (1975), Thorstensson (1976), and Silvester..(1976) found weight training effective in increasing vertical jump. Capen (1950) found significant increases in vertical jump, standing long jump and leg strength measures during a 12 week weight training program by a group of male college students. Significant gains in vertical jump were reported by Garth (1954) in a group of college basketball players involv- ed in a six week weight training study. A program of deep knee bends and toe raises with weights was reported by Ness and Sharos (1956) to increase leg strength and vertical jump. Brown and Riley (1957) reported significant 8 t r a i n i n g e f f e c t i n v e r t i c a l jump, leg strength and plantar f l e x i o n strength by a group of college basketball players involved i n a weight t r a i n i n g pro- gram. Similar r e s u l t s i n leg strength and v e r t i c a l jump gains were reported by Knudtson (1957) using female basketball players and by Chui (1960) using college men. Luitjens (1969) used two t r a i n i n g regimens, weight t r a i n i n g and Exer-Genie, and found s i g n i f i c a n t gains f o r , and i n s i g n i f i c a n t differences between the two groups i n explosive leg power and leg strength. Darling (1970) also used two t r a i n i n g conditions, deep knee bends and toe r a i s e s , and found s i g n i f i c a n t increases i n v e r t i c a l jump with i n s i g n i f i c a n t differences between groups. Tanner (1971) found that a group performing one set of RM deep knee bends showed s i g n i f i c a n t increases i n v e r t i c a l jump as did a group doing a s i m i l a r set at 50-60% RM. Again no s i g n i f i c a n t differences were found between groups. S t a h e l i et a l (1970) used three t r a i n i n g groups and one control group to investigate the e f f e c t s of isokenetic and i s o t o n i c exercise on leg strength, v e r t i c a l jump and thigh circumference. The con- di t i o n s were power rack, leg press and squats and a l l showed s i g n i f i c a n t increases i n a l l measurements but displayed no s i g n i f i c a n t differences between groups. Thorstensson (1970) found a regimen of squats and v e r t i c a l jumps resulted i n increases i n leg strength (measured by maximum squat), v e r t i c a l jump, standing broad jump and two legged isometric leg strength. Four t r a i n i n g conditions were implemented by S i l v e s t e r (1976) to compare the e f f e c t s of variable resistance and free weight t r a i n i n g on leg strength, v e r t i c a l jump, and thigh circumference. Two treatment groups did squats at 80% RM but one did three sets of s i x and the other one set of s i x and a second set to exhaustion. The other two conditions were use of the Nautilus Compound Machine and the Universal Dynamic Variable Resistance leg press s t a t i o n . A l l groups showed s i g n i f i c a n t gains i n leg strength and no gains i n thigh circumference. A s i g n i f i c a n t difference i n hip extension strength i n 9 favor of the three sets of s i x squat group over the Nautilus group was obtained i n a l l groups but the Nautilus group showed s i g n i f i c a n t increases i n v e r t i c a l jump. Roberts (1956), Charles (1966), Hansen (1969), and S i l v e s t e r (1976) have presented evidence that weight t r a i n i n g did not improve v e r t i c a l jump. A program of forward, l a t e r a l , and heel r a i s e s , squats and curls were report- ed by Roberts (1956) not to improve v e r t i c a l jump. Charles (1966) found no s i g n i f i c a n t increase i n v e r t i c a l jump but a s i g n i f i c a n t increase i n leg strength a f t e r completion of an explosive weight t r a i n i n g program. Hansen (1969) found that trampline or weight t r a i n i n g e i t h e r u t i l i z e d i n d i v i d u a l l y or i n combination did not produce improvement i n v e r t i c a l .jump. The Nautilus Compound machine was found by S i l v e s t e r (1976) not to produce improved v e r t i c a l jump performance. Fisher (1968), De Venzio (1969) and Tanner (1971) found that isometric exercise improved v e r t i c a l jump. Fisher (1960) compared the e f f e c t s of isometric exercise, weight t r a i n i n g , Exer-Genie t r a i n i n g and jumping with ankle spats on v e r t i c a l jump. I t was found that s i g n i f i c a n t increases i n v e r t i c a l jump were experienced by a l l groups with no s i g n i f i c a n c e between group e f f e c t . De Venzio (1969) found s i g n i f i c a n t improvement i n v e r t i c a l jump by a group performing isometric exercises and no increase i n leg or back strength from e i t h e r the isometric group or another group performing i s o t o n i c exercises. Tanner (1971) supported De Venzio's v e r t i c a l jump r e s u l t s but found dynamic overloading to be s i g n i f i c a n t l y better method of improving jump performance. Delacerda (1969) completed a t r a i n i n g study that f a i l e d to support isometric exercise as a means of improving v e r t i c a l jump. Fisher (1968) and Luitj e n s (1969) found the Exer-Genie improved v e r t i c a l jump as did Delacerda (1969) although i t was found that a rebound jumping program was as succ e s s f u l . E s c u t i a (1971) and Testone (1972) found that 10 isokinetic exercises performed on the Super Mini Gym increased leg strength significantly but not vertical jump. Van Oteghen (1973) used women in two training conditions of isokinetic exercise. Both groups performed leg presses, one taking four seconds for each repetition and the other group two seconds. Three sets of ten were completed in each session. At the end of eight weeks both groups showed significant increases in leg strength and vertical jump measures with the slow group showing a greater and significant difference in the leg strength. Copeland (1977) investigated the effects of isokinetic power training on a group of women's vertical jump. An Orthotron Exercise System was utilized.and set at a releasing speed of 250 deg/sec. A control group and train- ing group were formed with equal representation of good (high) and poor (low) jumpers. The trained poor jumpers showed significant increases in vertical jump while the trained jumpers did not. The effect of the use of ankle spats has been investigated by Anderson (1961), Fisher (1968) and Boyd (1969) . Anderson (1961) found that the experi- mental group improved significantly in vertical jump, 300 yard run and a g i l i t y tests. Fisher (1968) found ankle spats effective in improving vertical jump but Boyd (1969) found that there was no significant difference between his control and experimental group even though the experimental group showed significant improvement in jumping a b i l i t y . Isotonic exercises using body weights were found to be effective in increasing vertical jump in young males by Gibson (1961). Blucher (1965) found them to be ineffective in improving the jumping performance of college women and also reported insignificant correlations of leg strength with vertical jump or running speed. Jones (1972) found ankle exercises ineffect- ive in improving the jumping a b i l i t y of young boys although plantar flexion strength improved. 11 Marino (1960) found rope skipping improved v e r t i c a l jump as did Fisher (1968) when skipping with ankle weights. Quarles (1967) f a i l e d to support rope skipping as a method for improvement of v e r t i c a l jump but found that s t a i r running improved leg power. Tanner (1971) and Delacerda (1969) found jumping exercises e f f e c t i v e i n improving jumping a b i l i t y . Escutia (1971) with v o l l e y b a l l players supported these findings but a study by Roberts (1956) with basketball players f a i l e d to support t h i s . A l l e n (1962) found trampoline t r a i n i n g combined with rope skipping improved hip f l e x i o n strength. However, Brees (1961) and Hansen (1969) found trampoline t r a i n i n g i n e f f e c t i v e i n improving v e r t i c a l jump. Keohane (1977) investigated the e f f e c t of depth jump t r a i n i n g on v e r t i c a l jumping a b i l i t y on and o f f the i c e using a group of figure skaters as subjects. I t was found that a depth jumping program resulted i n s i g n i f i c a n t improvement i n v e r t i c a l jump both on and o f f the i c e and that the two parameters were s i g n i f i c a n t l y p o s i t i v e l y correlated. Scoles (1978) employed f l e x i b i l i t y and depth jumping groups and neither showed s i g n i f i c a n t gains i n v e r t i c a l jumping or standing long jump. Depth Jumping. Depth jumping i s a new form of t r a i n i n g that has been developed i n Europe, p r i m a r i l y i n the Soviet Union. Because of the problems of obtaining and t r a n s l a t i n g material there i s l i t t l e l i t e r a t u r e to be had on the subject i n North America. There have been several a r t i c l e s published a f t e r trans- l a t i o n from Russian and there are previous investigations of underlying p r i n c i p l e s that were completed i n Western Europe and North America. These findings w i l l be reviewed. 12 Muscle E l a s t i c i t y arid Prestretch. There i s apparently a s e r i e s - e l a s t i c component i n muscle that, when stretched, w i l l momentarily store energy that can be used during a subsequent contraction of that muscle (Marey and Demeny, 1885; Fenn, 1930; Fenn and Marsh, 1935; Cavagna, Dusman, Margaria, 1968; Thys, Faraggiano, Margaria, 1972). The e f f i c i e n c y of this action increases the sooner the muscle stre t c h i s followed by a concentric contraction (Asmussen and Bonde-Petersen, 1974; Cavagna et a l . , 1968). I t has been found that running was more e f f i c i e n t than walking i n u t i l i z i n g the energy stored i n the e l a s t i c component and walking i s more e f f i c i e n t than b i c y c l i n g . Marey and Demeny (1885) and Asmussen and Bonde-Petersen (1974) found that jumping with a counter-movement resulted i n better performance than jumping without a counter-movement. Again Asmussen and Bonde-Petersen (1974) found that per- formance was enhanced by more f o r c e f u l counter-movements obtained when jumping from heights of 0.233 m, 0.404 m and 0.690 m. The forces involved i n eccentric contraction and any subsequent concentric contraction are greater than those attained i n a motion inv o l v i n g prestretch (Cavagna et a l . , 1968; Thys et a l . , 1972; Asmussen and Bonde-Petersen, 1974). Cavagna et a l . (1968) found that muscles can develop more force during an eccentric contraction. Rodgers (1973) found that eccentric forces can be up to two times greater than isometric forces measured at the same muscle length. Cavagna et a l . (1968) reported that when eccen t r i c and isometric forces at the same muscle length were equal, subsequent concentric contractions resulted i n more work being done by the prestretched muscle than by the i s o m e t r i c a l l y contracted muscle. Cavagna et a l . (1968) also found that the c o n t r a c t i l e elements contracted with more force a f t e r prestretch and would continue to apply more force than an unstretched muscle as the v e l o c i t y of contraction increased. I t was also 13 reported that the force of eccentric and concentric contractions were greater as the muscle was stretched to longer lengths. The v e l o c i t y of the muscle s t r e t c h also has an e f f e c t on the forces developed. I t was found that as the speed of s t r e t c h increased the force developed increased (Fenn and Marsh, 1935; Cavagna et a l . , 1968) and the time of the p o s i t i v e contraction decreased (Thys et a l . , 1972; Asmussen and Bonde- Petersen, 1974). Myotatic Reflexes. I t has been reported that myotatic reflexes play a r o l e i n depth jumping (Ozolin, 1972; W i l t , 1975; Boosey, 1976; Scoles, 1978). M e l v i l l Jones and Watt (1971) reported three responses to stimulation, two of which were determined to be r e f l e x i v e i n character. The f i r s t E.M.G. a c t i v i t y occurred about 40 msec a f t e r i n i t i a l contact and resulted i n no muscular re- action. A l a t e r burst of a c t i v i t y a f t e r 120 msec represented the working r e f l e x i v e arc and resulted about 30 msec l a t e r i n actual muscular response. The t h i r d response time was that of voluntary expression and took 165 msec to occur. The second r e f l e x response was c a l l e d the f u n c t i o n a l s t r e t c h r e f l e x (FSR). M e l v i l l Jones and Watt (1971) also found that i n actual landing the FSR i s i n h i b i t e d and concluded that i t didn'.t play a r o l e i n a r r e s t i n g down- ward motion on landing. I t was f e l t that a l l muscular a c t i v i t y was pre- programmed before contact. In hopping movements, however, the FSR contributed to the upward motion, p a r t i c u l a r l y at a frequency of 2.06 hops/sec. This frequency had the subjects on the ground for 263 msec/hop and i t was found that e f f i c i e n c y was not as good at hopping frequencies e i t h e r smaller or larger than the favoured value. I t was reported that a r e f l e x i v e pattern i n i t i a t e d by the e f f e c t of free f a l l on the v e s t i b u l a r apparatus could play a part i n c o n t r o l l i n g the hopping action. 14 P r i n c i p l e s of Depth Jumping. Verhoshanskiy (1966) stated that t r a i n i n g only with weights or jump programs did not r e s u l t i n expected r e s u l t s i n per- formance. I t was f e l t that the reason for t h i s was that either program did not develop the reactive a b i l i t y of subjects and the idea was promoted that a form of exercise that developed t h i s reactive a b i l i t y should be undertaken. I t was put forward that depth jumps be u t i l i z e d i n t h i s d i r e c t i o n and that combined with weight t r a i n i n g they would r e s u l t i n good performances. In another a r t i c l e Verhoshanskiy (1967) reinforced the idea that further improvement i n performances would come from improving the reactive a b i l i t y of the nerve-muscle apparatus and t h i s could be done by employing "shock" methods. Namely by depth jumping. I t was f e l t that by combining jumping for depth with regular t r a i n i n g , maximum r e s u l t s could be obtained i n minimum time. Wilt, C e r u t t i , Embling, Toomsalu, Pross, McGuire and Schubert (1974) stated that improvement i n the r e l a t i o n s h i p between maximum strength and ex- plosive power could be brought about by employing plyometric d r i l l s . I t was thought that these d r i l l s r e l i e d on t h e i r success due to the prestretching of the muscles i n the amortisation phase of the movements, allowing the muscle to contract with greater force. Zanon (1974) recommended that plyometric exercise should employ as short an amortisation period as possible and that the pattern of the movement should remain as unaltered as p o s s i b l e . Lefroy (1974) recommended rebound jumping as an a c t i v i t y to develop expl- osive power and emphasized that the landing and jump should be one motion with no h e s i t a t i o n between the movements. Ecker (1975) f e l t that plyometric exercises were the best exercise for developing successful s p r i n t e r s . Wilt (1975; 1976) stressed that plyometric exercises were a b e n e f i t i n improving the r e l a t i o n s h i p between strength and power. I t was stressed that 15 plyometric exercises relied on eccentric contraction of the stretched muscles to develop greater force and speed of movement during the concentric contrac- tion. Wilt f e l t that the eccentric contraction also allowed the muscle to use a myotatic or stretch reflex contraction during the concentric contraction which aided in developing more force. Boosey (1976) recommended depth jumps for training and stressed a fast take-off after landing. It was f e l t that the f a l l i n g body mass stimulated the muscles to work, and i t was unnecessary to implement extra loading. Timing of the Jumps. Three factors play an important role in depth jump- ing and they are voluntary expression of force, elastic recoil and stretch reflex contraction (Ozolin, 1973; Boosey, 1976). Because of these factors the timing of the jump i s of the utmost importance. The amortisation phase of the jump should be as short as possible and equal in time to the extension phase (Katchajov, Gomberaze and Revson, 1976). The faster the landing and take-off, the more effici e n t l y force can be stored and transmitted by the series-elastic components of the muscle (Wilt et a l . , 1974; Asmussen, Bonde-Petersen, 1974; Wilt, 1975). Greater landing speed also allows the contractile elements to shorten with greater force during the concentric phase of contraction. These circumstances must then combine with the FSR which operates most effectively when 200-263 msec is spent on the ground during the jump. The legs must be bent at 130-135 deg (Ozolin, 1972) on f i r s t contact to prevent a damaging j o l t but care must be taken to prevent too great an absorption phase. The trunk and arms must be held in the proper attitude and carry out the proper actions as they can contribute up to 22% of the jump force (Luhtanen and Komi, 1978). 16 Optimum Height. Asmussen and Bonde-Petersen (1974) reported that maxi- mum reaction force and jump height were obtained i n t h e i r study when depth jumps were performed from 0.404 m. The rebound jump and jump height were approximately equal at t h i s l e v e l . Jumps from 0.233 m and 0.690 m were not as f o r c e f u l as those from 0.404 m. Verhoshanskiy (1967) states that jumps from 0.75 m resulted i n maximum speed of the muscles i n switching from negative to p o s i t i v e work and that jumps from above 1.10 m resulted i n harm being done to the jump s k i l l . Katchajov, et a l . (1976) found that rebound height i n a depth jump reached a maximum at 0.80 m. At t h i s height amortisation and take-off phases were approximately equal and at t h e i r minimum i n duration. Repetition i n Depth Jump Training. Verhoshanskiy (1967) states that 40 jumps twice a week i s a reasonable program because i t takes longer to recover from t h i s type of work. He suggests sets of 10 with running and s t r e t c h i n g exercises between. Zanon (1974) suggests s i x to 10 sets of f i v e to eight r e p e t i t i o n s with 10 to 15 minute rests between the sets. Lefroy (1974) recommends f i v e short work periods of f i v e to 15 seconds duration with a minute rest between them. Keohane:: (1977) used f i v e exercises with a t o t a l of 15 sets and 80 r e p e t i - tions, and Scoles (1978) used a program of 20 jumps per session. Progression and Overload i n Depth Jumping. Verhoshanskiy (1967) states that i t i s preferable to create overload by increasing jump height leaving the r e p e t i t i o n s and weight load the same. Extra mass w i l l increase the time spent on the ground and more re p e t i t i o n s w i l l r e s u l t i n an endurance workout. The maximum height, of course, should not exceed 1.10 m. 17 Introduction to Athlete's Program. Verhoshanskiy (1966) noted that as athletes became more advanced t h e i r t r a i n i n g f a i l s more and more to bring t h e i r performances i n l i n e with projected expectations. I t i s f e l t that t h i s i s due to the f a c t that s k i l l p r a c t i c e and weight t r a i n i n g f a i l to increase and some- times decrease the athlete's reaction a b i l i t y . S k i l l p r a c t i c e and weight t r a i n i n g can cause large improvements, p a r t i c u l a r l y among novices, and Verho- shanskiy ranks athletes on that c r i t e r i a . Class III athletes, novices whose strength i s low, do a general developmental strength and jump program with mod- erate loading. Class II athletes, intermediate i n experience and strength, use weights at 75-90% maximum and form a base for the explosive a c t i v i t i e s desired. Class I and Master of Sport athletes, who are national and i n t e r - national l e v e l competitors, d i r e c t t h e i r e f f o r t s to improving reaction a b i l i t y i n the nerve-muscle apparatus through depth jumping and performing weights at 100% maximum. Verhoshanskiy (1966) f e e l s that athletes should s t a r t at t h e i r indicated l e v e l and then work towards the top l e v e l before doing depth jump t r a i n i n g . Summary. From the l i t e r a t u r e at hand a l l weight l i f t i n g except that employing the Nautilus Compound machine were e f f e c t i v e i n improving v e r t i c a l jump performance. (Capen, 1950; Garth, 1954; Ness and Sharos, 1956; Brown and Rile y , 1957; Knudtson, 1958; Chui, .I960; L u i t j e n s , 1969; Darling, 1970; Tanner, 1971; S t a h e l i et a l . , 1975; Thorstsson et a l . , 1976; and S i l v e s t e r , 1972). Isometric exercises were found to be e f f e c t i v e i n improving jumping a b i l i t y by Fisher (1968), De Venzio (1969) and Tanner (1971) and i n e f f e c t i v e by Delacerda (1969). I s o k i n e t i c exercises were found to increase v e r t i c a l jump (Fisher, 1968; Lui t j e n s , 1969; and Delacerda 1969) by using the Exer-Genie and by Van Oteghen (1973) using the Compensator leg press machine. Escutia (1971) and Testone 18 (1972) found the Super Mini Gym ineffective in improving vertical jump and Copeland (1977) found the Orthotron Exercise System effective in improving vertical jump for only those classified i n i t i a l l y as poor jumpers. Use of ankle weights improved jumping a b i l i t y in studies by Anderson (1961) and Fisher (1968), and lead to ambiguous results by Boyd (1969). Blucker (1965) and Jones (1972) found isotonic exercises unsuccessful in improving vertical jump but Gibson (1961) obtained results counter to those findings. Marino (1960) and Fisher (1968) found skipping conductive to jumpr- ing increases. Quarles (1967) did not support these results but concluded that stair running improved leg power. Delacerda (1969), Escutia (1971), and Tanner (1971) found that repeated jumping exercises were successful. Roberts (1956) found that they did not enhance jumping a b i l i t y . Trampoline training was found to be ineffective in improving leg power by Brees (1961) and Hansen (1969) and effective by Allen (162). Keohane (1977) concluded that depth jump training was successful in improving vertical jump but Scoles (1978) failed to support these findings. Of the methods reviewed weight training seems to have been the most con- sistent in improving vertical jump. Depth Jumping is a form of training which utilizes the physiological effects of muscle stretch to increase force during the following concentric contrac-r tions. The training program increases the reactive a b i l i t y of the athlete by emphasizing a fast explosive landing and take-off from a predetermined height. The height chosen allows the amortisation and extension phases to be equal in duration and results in a rebound height matching the i n i t i a l jump height. Depth jumping is designed for advanced athletes who have undertaken pre- vious strength training. Overload is created by increasing the height jumped from, not by weight loading or increasing the number of repetitions. 19 Chapter 3 METHODS AND PROCEDURES Subjects Thirty-eight male athletes from university teams volunteered to take part in the study. Three groups were formed with equal team representation in each group but with random selection as to which group any particular individual was assigned. One group was an overload group, another was a normal load group jumping from sub-optimum height and the third was a normal load group jumping from i t s . optimum height. Groups The normal load group jumping from their optimum heights had high momenta and high velocities of landing. The overload group had high momenta but low velocities of landing. The landing momenta of the subjects were equal to the landing momenta they would have attained i f they were in the normal load optimum height group. The normal load group jumping from sub-optimum height had low momenta and moderate velocities of landing. The subjects jumped from a height that was midway between their optimum height and the height they would have jumped from had they been in the over- load group. Time and Duration of the Study The study took place over a six week period and formed another exercise period in addition to normal practices. There were two training sessions per week for the f i r s t three weeks and three times per week for the last three weeks. 20 TESTS Three test sessions were held: pretest, at the beginning of the study; midtest, at the end of the third week; and post test, at the end of the study. A l l subjects were tested on the Sargeant Jump Test, a Standard Depth Jump Test and with a cable tensiometer to determine knee extension and plantar flexion strength. Their weight was measured during the pretest and their optimum height (and therefore momentum) for a depth jump was determined at each testing. Prior to the pretest subjects attended a familiarization session where they were introduced to the tests and allowed to practice them and were also taught how to execute a proper depth jump. During a test period reaction force readings were collected by use of a Kistler type 9261A force plate, Kistler type 5001 Charge Amplifier and a M.F.E. 3 channel 100 mm recorder. The data included readings taken for overload, normal load at sub-optimum and normal load at optimum depth jumps. An analysis of reaction force data was done comparing the peak forces, impulses and times between the three jump conditions. Sargeant Jump Test The subjects were f i r s t measured for their maximum vertical reach with the hand of their choice using an' calibrated wall board. They then stood to the side of another calibrated board and without shuffling their feet jumped and reached as high as possible making contact with the board at the apex of their jump. Standard Depth Jump Test The subjects jumped down from an 18 in height, executed a two footed jump and reached as high as possible. The height attained was measured as 21 i n the Sargeant Jump Test. Cable Tensiometer Tests The strength of the knee extensors was determined at a 115 deg angle at the knee j o i n t . The plantar f l e x i o n strength was determined with the ankle j o i n t at a 90 deg angle. PROCEDURES FOR THE DEPTH JUMPING PROGRAMS The program was preceded by i n d i v i d u a l warm-up sessions comprised of each subject's normal routine. The program i t s e l f was performed as four sets with eight r e p e t i t i o n s i n each set for the f i r s t three weeks. The second three weeks en t a i l e d a pro- gram of f i v e sets of eight r e p e t i t i o n s three times a week. Each r e p e t i t i o n followed without delay the previous one with one to two minutes rest between each set. Two test groups, the overload group and the normal load group jumping from optimum heights, had the same momentum of landing, the difference being that the overload group had greater mass and less v e l o c i t y while the optimum height group had less mass but greater v e l o c i t y . The t h i r d group had the same mass as the optimum group but had a smaller v e l o c i t y and therefore had a lower landing momentum. This meant that the overload group jumped from lower heights than the normal load groups and wore weight jackets that had a weight 15% of the body weight. The normal load at sub-optimum subjects jumped from a height midway between the optimum determined i n t e s t i n g and the height they would have jumped from i f they had been assigned to the overload group. The normal load at optimum height subjects jumped from t h e i r optimum height 22 as determined during testing. The various training heights were determined by calculating the velocity that a free f a l l i n g object would attain when released from each of the heights in the training range. Taking these heights as optimum training heights, the overload training heights were calculated by dividing the optimum height vel- ocities by 1.15 (see appendix B) and matching the resulting figure with the height displaying the nearest velocity (Table 1). The training heights for the unloaded sub-optimum group were determined by selecting the height midway between their optimum and calculated loaded heights. The training heights are liste d in Table 2. Training heights for the subjects were altered after the midtest i f there was a change in their measured optimum height. This was done in order to maintain the proposed training conditions. Subjects were instructed to follow the principles l a i d down by Lefroy . . (1974) : 1. Each jump should be a maximum effort. 2. Each set of jumps should be done quickly without pauses between jumps. 3. Each jump should be a bounce executed as quickly as possible. EXPERIMENTAL DESIGN The study was a 3 x 3 factorial with repeated measures on the second fac- tor (figure 1). The independent variables were the treatment factors with 3 levels (optimum, overload, unloaded at sub-optimum) and the time factor with three levels (pre, mid, post). Four dependent variables were measured; sar- geant jump height, standard depth jump height, knee extension strength and plantar flexion strength. 23 Table 1 V e l o c i t i e s Attained In The Training Height Range Height (in) V e l o c i t y (ft/sec) Height (in) V e l o c i t y (ft/sec) 34 . 13.47 22 10.83 33 13.27 21 10.58 32 13.06 20 10.33 31 12.86 19 10.07 30 12.65 18 9.80 29 12.44 17 9.52 28 12.22 16 9.24 27 12.00 15 8.94 26 11.78 14 8.64 25 11.55 13 8.33 24 11.31 12 8.00 23 11.08 24 Table 2 Training Heights Optimum Height (in) Loaded Height (in) Unloaded Sub-Optimum Height (in) 34 26 30 33 25 29 32 24 28 31 23 27 30 23 26 29 22 25 28 21 24 27 20 23 26 20 23 25 19 22 24 18 21 23 17 20 22 17 19 21 16 18 20 15 17 19 14 16 18 14 16 17 13 15 25 The force plate analysis was 1 x 3 factorial with repeated measures on the second factor. The independent variables were the treatment factors with 3 levels (optimum, overload and unloaded at sub-optimum) and the group factor with one level. Eleven dependent variables were measured; landing force, dip force, jump force, total impulse, landing impulse, jump impulse, half jump impulse, total time, landing time, jump time and half jump time. Figure 1 Experimental Design Groups Pre Mid Pos Optimum S 1 10 Loaded S l l 20 Unloaded sub-optimum S21 28 26 STATISTICAL TREATMENT A 3 x 3 f a c t o r i a l analysis of variance with repeated measures on the sec- ond factor was performed on the four dependent variables using the program BMV:P2V (Halm, 1974). Each hypothesis was tested at an alpha l e v e l of .05. The Pearson Product Moment C o r r e l a t i o n was used to determine the mag- nitude of the l i n e a r r e l a t i o n s h i p between the dependent variables for each t r a i n - ing program during each t e s t i n g session using the program U.B.C. Simcort (Le, 1974) and were tested at the .05 l e v e l to determine i f they were s i g n i f i c a n t l y d i f f e r e n t from zero. For the analysis of the force platform data a 1 x 3 f a c t o r i a l analysis of variance with repeated measures on the second factor was performed on the eleven dependent variables using the program BMD:P2V (Halm, 1974) and tested for s i g n i f i c a n c e at an alpha l e v e l of .05. Post-hoc Newman-Kuels multiple comparison tests were administered to those variables which displayed s i g n i f i c a n t differences to f i n d where the differences a c t u a l l y were. They were tested at the .05 l e v e l . 27 Chapter 4 RESULTS AND DISCUSSION T h i r t y - e i g h t subjects volunteered to take part i n th i s study and were pretested with the Sargeant Jump Test , Standard Depth Jump Tes t , Knee F lex ion Strength Test and P lantar F lex ion Strength Tes t . The i r optimum depth jump height was a l so determined at th i s t ime. Ten subjects d id not complete the study as three suffered i n j u r i e s which precluded further t r a i n i n g and seven others withdrew through personal choice . Three subjects were l o s t from the optimum group, three from the overload group and four from the sub-optimum, unloaded group. E ight subjects p a r t i c i p a t e d i n the force p la te ana lys i s of the three t r a i n i n g cond i t ions . The re su l t s of th i s i n v e s t i g a t i o n and the d i scus s ion of the r e s u l t s are d iv ided in to two sec t ions . The f i r s t s ec t ion deals with the e f fects of depth jump t r a i n i n g on v e r t i c a l jump, depth jump, leg extension s trength and p lantar f l e x i o n s t rength . The second sec t ion deals wi th the force plat form ana lys i s of the three depth jump t r a i n i n g cond i t ions . Resul t s : The E f f ec t of V e r t i c a l Jump T r a i n i n g on Sargeant Jump, Standard Depth Jump, Knee Extension Strength and P lantar F l e x i o n Strength. The fo l lowing re su l t s deal wi th the major purpose of t h i s study, which i s to inves t iga te the e f fects on v e r t i c a l jump of three s i x week depth jump t r a i n i n g programs. The observed c e l l means for the optimum, loaded and unloaded sub-optimum groups are presented i n Table 3. Table 4 shows the t r i a l means for a l l sub- j ec t s and a l so di splays the standard dev ia t ions . Tables 5 through 11 conta in the ana lys i s of variance and summaries of t rends . 28 Table 3 Observed C e l l Means Group Dependent Variable Pre Mid Post Optimum S...J. (in) 22 80 24. 80 25 40 S .D.J. (in) 24 00 25. 60 26 20 K.E. (lb) 219 50 218. 00 220 50 P.F. (lb) 257 40 312. 70 331 60 Loaded S.J. (in) 21 70 24. 00 24 40 S .D.J. (in) 22 40 24. 80 25 10 K.E. (lb) 233 30 238. 40 246 20 P.F. (lb) 244 20 305. 70 344 70 Unloaded S.J. (in) 23 25 24. 50 24 .75 Sub-Optimum s .D.J. (in) 23 88 25. 25 26 00 K.F. (lb) 250 88 268. 50 256 50 P.F. (lb) 251 50 321. 00 363 .125 Table 4 Observed T r i a l Means T r i a l Measure Sargeant Depth Knee Plantar Jump Jump Extension Flexion (in) (in) (lb) (lb) Pre X 22.54 23.39 233.39 251.00 S.D. 2.56 2.53 41.67 49.26 Mid 1 24.43 25.21 239.71 312.57 S.D. 2.74 2.86 38.21 40.25 Post X 24.86 25.75 239.96 345.29 S.D. 2.69 3.01 41.55 57.89 29. Observation of Table 5 reveals that a l l groups improved significantly in the sargeant jump over the six week period. This is indicated by the t r i a l s row where F is 55.78. C r i t i c a l F for 2 and 50 deg of freedom is 3.18 at the,.05 alpha level and 5.06 at the .01 alpha level (Ferguson, 1959) so the t r i a l s effect is highly significant with a P of .001. It can also be seen that there were no significant differences between the groups in improvement. Table 6 indicates that the improvements were significantly linear and quadratic in nature. C r i t i c a l F values for 1 and 25 deg of freedom are 4.24 at the .05 level and 7.77 at the .01 level. The F values for the linear and quadratic effects are 62.95 and 30.07 respectively so both are highly significant. Table 7 shows that standard depth jump increased significantly during the study and there was no significant differences between the groups (F 48.19, P .001). Again, as for the sargeant jump, there are significant linear (F 64.81, P .001) and quadratic (F 12.39, P .001) trends as seen in Table 8. Table 9 indicates that there are no significant training effects for knee extension strength. The c r i t i c a l F at the .05 level i s 3.18 but the knee extension F is only .82 and must exceed c r i t i c a l F to be significant. Table 10 shows that plantar flexion strength improved for a l l groups equally. This can be seen by the F value for the t r i a l s effect (F 59.99, P .001) which indicates that a l l groups improved over the training period and by the group x t r i a l s interaction which is insignificant (F .86, P .492). Significant linear and quadratic trends are seen in Table 11 with the linear F being 93.19 (P .001) and the quadratic F 4.82 (P .038). Tables 12, 13 and 14 present the correlation coefficients for each group calculated between each dependent variable for each test period. It can be seen that the only significant correlations occur between sargeant jump and depth jump and between knee extension and plantar flexion strength. For a l l subjects the correlation coefficient for sargeant jump and standard depth 6 30 jump at the pretest was .89, at the midtest .91 and for the posttest .91 (a l l significant at the .01 level). The knee extension and plantar flexion strength correlation coefficients at. pre, mid and posttest were .62 (sig- nificant at the .01 level), .39 (significant at the .05 level) and .49 (significant at the .01 level). Hypotheses. The f i r s t hypo-thlesis states that as a result of depth jump training there is a significant increase in jumping ab i l i t y for a l l test groups. This hypothesis is supported since a l l groups have shown sig- nificant increases at the.01 level in the Sargeant Jump Test and the Standard Depth Jump, Tes t. The second hypothesis states that as a result of depth jump training the test groups show a significant increase in the leg strength test. This hypothesis is partially supported as a l l groups showed significant gains at the .01 level in the plantar flexion strength test but no significant change in the knee extension strength test (not significant at .05 level). The third hypothesis states that the overload (low velocity, high momentum) group shows a significant leg strength increase over the two normal load groups. This hypothesis i s not supported as there was no significant d i f - ference between groups on either leg strength measure. The fourth hypothesis states that the normal (high velocity, high momentum) group jumping from optimum height shows a significant increase in jumping a b i l i t y over the normal load (moderate velocity, low momentum) group jumping from sub-optimum height which shows a significant increase in jumping a b i l i t y over the overload group. This hypothesis was not support- ed since a l l groups improved significantly in jumping a b i l i t y but not at a rate significantly different from each other. 31 Table 5 3 x 3 Anova Of Sargeant Jump Source D.F. . Mean Square F : P Grand Mean 1 47674.95 - - Groups 2 7.87 .38 .688 Error 25 20.76 Trials 2 40.31 55.78 .001 Trials x. .Groups 4 : i:. 10 1.53 .209 Error 50 0.72 Table 6 Summary of Trend for Sargeant Jump Source D.F. Trials Linear 1 Error 25 Trials Quadratic 1 Error 25 Mean Square 71.14 1.13 9.48 .32 F 62.95 30.07 P .001 .001 32 Table 7 3 x 3 Anova Of Standard Depth Jump Source D.F. Grand Mean 1 Groups 2 Error 25 T r a i l s 2 T r i a l s x Groups 4 Error 50 Mean Square F 51106.79 11.31 .50 22.81 41.52 48.19 .69 .80 .86 .615 .001 .53 Table 8 Summary Of Trend For Standard Depth Jump Source T r i a l s Linear Error T r i a l s Quadratic Error D.F. 1 25 1 25 Mean Square F 75.92 64.81 1.17 7.12 .55 12.89 P .001 .001 33 Table 9 3 x 3 Anova Of Knee Extension Strength Source D.F. Grand Mean 1 Groups 2 Error 25 Trials 2 Trials x Group 4 Error 50 Mean Square 4748819.00 10353.09 3499.95 428.01 349.00 466.41 2.96 .92 .75 .070 .41 .56 Table 10 3 x 3 Anova Of Plantar Flexion Strength Source D.F. Grand Mean 1 Groups 2 Error 25 Trials 2 Trials x Groups 4 Error 50 Mean .Square F 7649681.00 1406.22 0.25 5597.08 64615.47 59.99 930.28 .86 1077.10 .780 .001 .492 34 Table 11 Summary Of Trend For Plantar Flexion Strength Source D.F. Mean Square F P T r i a l s Linear. 1 125333.88 93.19 .001 Error 25 1344.93 T r i a l s Quad. 1 3897.09 4.82 .038 Error 25 809.27 Table 12 Pretest C o r r e l a t i o n C o e f f i c i e n t s Variables r Optimum Loaded Between S.J. and D.J. ,.89** .92** .90** .84** S.J. and K.E. .05 .13 .07 -.17 S.J. and P.F. .09 .06 .03 .15 D.J. and K.E. .001 .02 -.16 .16 D.J. and P.F. .09 .21 -.25 .30 K.E. and P.F. .62** .40 .89** .78*" * s i g n i f i c a n t at the .05 l e v e l ** s i g n i f i c a n t at the .01 l e v e l 35 Table 13 Midtest C o r r e l a t i o n C o e f f i c i e n t s Variables r Optimum Loaded Between S.J. and D.J. .91** .92** .97** .83* S.J. and K.E. .14 .26 .49 -.24 S.J. and P.F. .13 .24 .28 -.26 D.J. and K.E. .14 .26 .50 -.17 D.J. and P.F. .17 .18 .24 .07 K.E. and P.F. .39* .13 .55 .60 * s i g n i f i c a n t at the .05 l e v e l ** s i g n i f i c a n t at the .01 l e v e l Table 14 Posttest C o r r e l a t i o n C o e f f i c i e n t s Variables r Optimum Loaded Between S.J. and D.J. .91** .94** .91** .82* S.J. and K.E. .06 .14 .10 .10 S.J. and P.F. .002 .30 -.04 -.36 D.J. and K.E. .07 .17 .19 -.22 D.J. and P.F. -.001 .15 -.07 -.11 K.E. and P.F. .49** .46 .71* .11 * s i g n i f i c a n t at the .05 l e v e l '* s i g n i f i c a n t at the .01 l e v e l 36 Discussion Although jumping a b i l i t y increased for a l l groups during the study there were no observable differences i n the rate of improvement of the groups. That i s , no group or groups improved s i g n i f i c a n t l y over any other group or groups. Two conditions of landing momentum and three conditions of landing v e l o c i t y were examined i n t h i s study and no s i g n i f i c a n t differences were r e a l i z e d between the conditions when comparing change i n any of the measured parameters. The t r a i n i n g heights are l i s t e d i n Table 2. I f three subjects had the same optimum height depth jump (e.g. 28 in) but were i n d i f f e r e n t t r a i n i n g groups t h e i r t r a i n i n g heights were 28 i n for the optimum height group, 21 i n for the loaded group and 24 i n for the unloaded at sub-optimum height group. From Table 1 the landing v e l o c i t i e s for these heights are 12.22 f t / s e c from 28 i n , 10v'58.".ft/sec .from 21 i n and 11.31 f t / s e c from 24 i n . If a l l three subjects had the same body weight (e.g. 160 lb) and therefore mass (m=lb/g=160/32=5.0 slugs) then the landing momenta (mxvel of landing) would be: from 28 i n , (12.22) 5=61.10 lb-sec; from 21 i n , (10.58) (5(1.15))= 60.84 lb-sec; and from 24 i n , (11.31) 5=56.55 lb-sec. Perhaps the momenta and v e l o c i t i e s used i n t h i s study were too s i m i l a r to each other for any differences to be seen with the number of subjects used. This study has shown that depth jumping increases jumping a b i l i t y . This indicates that the jump take-off v e l o c i t y increased which indicates that an improvement i n leg power was l i k e l y and supports Verhoshanskiy (1966, 1967, 1974) who stated that depth jumping i s an e f f e c t i v e method of improving leg power. This also supports Wilt (1974) and Zanon (1974) who f e l t depth jumping i s a plyometric exercise that helps muscles use t h e i r strength to generate power for jumping events. The r e s u l t s of t h i s study 37 support Keebane who found a depth jumping program improved jumping both on and o f f the i c e , and do not support Scales (1978) who reported no v e r t i c a l jump increases a f t e r a depth jumping program was undertaken. The improvement i n jumping a b i l i t y may be a r e s u l t of power increases and the possible reasons for these increases should be discussed. Secher, Rorsgaard and Secher (1976) reported that two leg extension strength i s approximately 87% of twice the average of one leg extension strength and gave i n d i r e c t evidence of decreased motor unit a c t i v i t y during two leg extension as compared to one leg extension. I t was also indicated that t r a i n i n g causes recruitment of more motor units r e s u l t i n g i n more force being exerted. Tesch and Karlson (1977) reported that maximum isometric strength (MIS) was l i n e a r l y correlated at the .001 l e v e l with r e l a t i v e d i s t r i b u t i o n of fast twitch (FT) f i b r e s . Thorstensson (1976) found hypertrophy i n the FT f i b r e s a f t e r an eight week weight t r a i n i n g program and found that f a s t i s o k i n e t i c contractions of the leg depend on the r e l a t i v e d i s t r i b u t i o n of the FT f i b r e s . He also reported that enzyme a c t i v i t i e s associated with rapid ATP synthesis increase when fa s t maximal contractions are repeated f i v e to eight times with b r i e f rest i n t e r v a l s . In t h i s study the t r a i n i n g program was such that FT f i b r e s may have hypertrophied as they are r e c r u i t e d at high muscle tensions and under 'sprint t r a i n i n g ' r e p e t i t i o n s . I f t h i s were so, the MIS should have increased s i g n i f i c a n t l y . In t h i s study knee extension strength did not improve but plantar f l e x i o n strength did. This may mean that the increase i n jump height was due to increases i n plantar f l e x i o n strength. However the c o r r e l a t i o n c o e f f i c i e n t s reveal no s i g n i f i c a n t r e l a t i o n s h i p between v e r t i c a l jump and plantar f l e x i o n strength. Correlations are based on selected ordering so when comparing 38 the two measures the strongest subjects may not necessarily be the best jumpers or the weakest subjects the poorest jumpers. This could result in low correlations. However, an increase in plantar flexion power what- ever the i n i t i a l level may result in improvement of vertical jump. If this is true a l l subjects could have improved their jumping abilityyby improv- ing their plantar flexion power and not affected the correlation coefficient because they would keep their relative order. For a l l subjects plantar flexion strength improved an average of 38% and sargeant jump improved an average of 10%. Theoretically plantar flexion contributes 22% to the jump (Luhtanen and Komi, 1978). If power gains matched strength gains, increased plantar flexion strength would acc- ount for approximately 80% of the vertical jump gains. To the investigators knowledge there have been no studies which correlated MIS changes to fibre contraction speed so i t i s speculative to state that plantar flexion strength gains explain gains in vertical jump. Another explanation for the jump improvement could be learning factors in which more motor units are recruited during the jump training. This could also be an explanation for the plantar flexion strength increases. Improved performance because of better coordination of trunk and limb action, is thought to be of l i t t l e importance in this study as the majority of sub- jects involved were experienced jumpers prior to the study. The jumping increases in this study as can be seen in Tables 6 and 8 were significant in trend both linearly and quadraticly. However, observ- ation of the t r i a l means (Table 4) indicates a levelling of the rate of increase. This indicates a quadratic curve which means that continued training would have resulted in decreasing gains. Table 11 shows that the trend for plantar flexion strength was significant both linearly and quad- raticly. The level of significance is .05 for the quadratic trend while i t 39 is .01 for the linear trend. This would indicate that there were s t i l l large strength gains to be made in this program although the curve would have eventually approached an asymptote. Hypothesis two was not supported wholly because leg extension strength showed no significant gains. Two possible explanations for this are: the nature of the measuring apparatus prevented subjects from exerting maximum force; or that tension developed in the thigh muscles was not enough to cause hypertrophy of the FT fibres (Thorstensson, 1976). The f i r s t explana- tion is not valid as the same cable tensiometer was used for both strength tests and as can be seen from the results the subjects were able to show that there had been an increase in plantar flexion strength. The second explana- tion is more reasonable as the thigh has a greater cross-sectional area than the calf. A tension high enough to cause hypertrophy of FT fibres in the calf may not be high enough when dispersed in the thigh to cause hyper- trophy of FT fibres there. The correlation coefficients of knee extension strength to plantar flexion strength were significant over the tests at the .05 level (r = .62, r . = .39 and r = .49) which indicates that subjects pre mid post strong on one test were strong on the other. These correlations would indi- cate that selected order was maintained in knee extension strength and that lack of significant improvement in knee extension strength was due to lack of training effect rather than error in measurement. The third hypothesis was not supported as there were no significant differences in the leg strength tests between groups. MIS is directly correlated with relative distribution of FT fibres (Tesch and Karlsson, 1977) and FT fibres hypertrophy when under tension (Thorstensson, 1976). The tensions developed in the three conditions may not have ^differed enough to cause significant differences in MIS. 40 The fourth hypothesis was not supported by t h i s study. An explanation for t h i s may be that the t r a i n i n g momenta or v e l o c i t i e s did not d i f f e r enough to cause s i g n i f i c a n t differences i n the rates of improvement. Corr e l a t i o n C o e f f i c i e n t s . The c o r r e l a t i o n c o e f f i c i e n t s reveal that a strong r e l a t i o n s h i p existed between sargeant jump and standard depth jump. A l l r values are s i g n i f i c a n t at the .02 l e v e l and indicate that good sar- geant jumpers were good depth jumpers i n terms of height attained ( r p r e = -89, r . = .92, r = .91). When comparing the means of the sargeant jump and mid post standard„depth;" jump (Table 4) i t can be seen that the means of the standard depth jumps were approximately .85 of an inch higher than those of the sargeant jumps. The high c o r r e l a t i o n c o e f f i c i e n t s indicate that for both jumps each subject was i n the same order r e l a t i v e to the other subjects. This means that most subjects jumped higher i n the standard depth jump than i n the sargeant jump. This supports the r e s u l t s reported by Asmussen and Bonde-Petersen (1974) who found that t h e i r subjects jumped higher during the rebound jump of a depth jump than during a sargeant jump. The only other c o r r e l a t i o n s that were s i g n i f i c a n t were those between knee extension strength and plantar f l e x i o n strength and they revealed that subjects who ranked high on one test ranked high on the others. Summary. Sargeant jump, depth jump and plantar f l e x i o n strength improved during the t r a i n i n g programs. Knee extension strength did not improve. There were no s i g n i f i c a n t between groups differences on the v e r t i c a l jump, depth jump and plantar f l e x i o n measures. Results': Force Platform Analysis of the Three Training Conditions. The following r e s u l t s deal with the analysis of the reaction force c h a r a c t e r i s t i c s of each of the three types of t r a i n i n g depth jumps. 41 The data recorded from the tracings was obtained by measuring various parameters of these tracings. Figure 2 i s a reproduction of a recording and the parameters measured are indicated. The shape of the tr a c i n g matches that reported by Asmussen and Bonde-Petersen (1974). The various measures were l a b e l l e d , for convenience, as follows; landing force, dip force, jump force, t o t a l impulse, landing impulse, jump impulse, h a l f jump impulse, t o t a l time, landing time, jump time and h a l f jump time. These la b e l s are adapted' descriptions of the data. Landing, jump and h a l f jump times are not e n t i r e l y correct as they were calculated, using as boundaries the dip minimum and jump force maximum. Table 15 shows the means and standard deviations f o r each v a r i a b l e measured. Tables 16, 17, 18, 19, 21, 22, 24, 26, 27, 28, 29, display the analyses of variance of each v a r i a b l e when compared over the three types of jumps. For 2 and 14 deg of freedom c r i t i c a l F at the .05 l e v e l i s 3.74 and at the .01 l e v e l i s 6.51 (Ferguson, 1959). As can be seen from the tables there were no s i g n i f i c a n t differences i n landing force (F .46, P .639), jump force (F 1.39, P .281), dip force (F .41, P .678), t o t a l time (F .689, P .519), landing time (F 1.43, P .272), jump time (F 1.76, P .208), h a l f jump time (F .715, P .506), or landing impulse (F 1.44, P .270) bet- ween the three conditions. T o t a l impulse (F 6.88, P .008), jump impulse (F 11,33, P .001), and h a l f jump impulse (F 4.50, P .031) did show s i g n i f i c a n t F values. Figure 2 FORCE PLATFORM TRACINGS 0 .2 0 ,..2 ,0 Time (sec) 1. Landing Force (L.F.),(lb) 2. Dip Force (D.F.) (lb) 3. Jump Force (J.F.) (lb) 4. Total Impulse (T.I.) (lb-sec) 5. Landing Impulse (L.I.) (lb-sec) 6. Jump Impulse (J.I.) (lb-sec) 7. . Half Jump Impulse (H.J.I.) (lb-se 8. Total Time (T.T.) (sec) 9. Landing Time (L.T.) (sec) 10. Jump Time (J.T.) (sec) 11. Half Jump Time (H.J.T.) (sec) 43 Table 15 Means.of Variables Variables L.F. (lb) J.F. (lb) D.F. (lb) T.I. (lb-sec) L.I. (lb-sec) J . I . (lb-sec) H.J.I, (lb-sec) T.T. (sec) L.T. (sec) J.T. (sec) H.J.T. (sec) X S.D. X S.D. X S.D. X S.D. X S.D. X S.D. X S.D. X S.D. X S.D. X S.D. X S.D. Optimum 789.54 63.17 714.69 104.79 197.99 112.51 170.61 24.94 51.26 17.79 119.35 25.00 90.88 31.60 .32 .07 .08 .02 .23 .05 .18 .07 Loaded 770.22 62.32 726.77 65.25 193.16 123.90 187.03 28.91 43.17 8.88 143.86 25.81 113.10 32.38 .34 .04 .07 .01 .27 .04 .21 .06 Between 784.71 68.44 705.03 88.22 224.55 85.73 169.23 18.26 46.30 17.09 122.75 23.29 86.73 31.17 .32 .05 .08 .02 .25 .06 .19 .08 44 Table 16 .Anova Of Landing- Force Source D.F. Mean Square F P T r i a l s 2 808.26 ,.46 .639 Error 14 1750.01 Table 17 Anova Of Jump Force Source D.F. Mean Square F P T r i a l s 2 948.50 1.39 .281 Error 14 681.73 Table 18 Anova of Dip Force Source D.F. Mean Square F P T r i a l s 2 2285.22 .41 .673. Error 14 5607.55 Table 19 Anova of Total Impulse Source D.F. Mean Square F P Trials 2 784.23 6.88 .008 Error 14 114.03 Table 20 Newman-Kuels Multiple Comparison Test Of Total Impulse Table of Q Between Optimum Loaded Between .37 4.71* Optimum 4.34** Loaded * significant at .05 level (Q2= 3.03, Q3= 3.70) ** significant at .01 level (Q2= 4.21, Q3= 4.89) 46 Table 21 Anova Of Landing Impulse Source D.F. Mean Square F P T r i a l s 2 M 3 3 . 0 9 1.44 v27 Error 14 92.41 Table 22 Anova Of Jump Impulse Source D.F. Mean Square F P T r i a l s 2 1401.20 11.23 .001 Error 14 124.75 47 Table 23 Newman-Kuels Multiple Comparisons Test Of Jump Impulse Table of Q Optimum Between Optimum .09 Between Loaded * significant at .05 level (Q2= 3.03, Q3= 3.70) ** significant at .01 level (Q2= 4.21, Q3= 4.89) Table 24 Anova Of Half Jump Impulse Source D.F. Mean Square F Trials 2 1608.26 4.50 Error 14 357.66 Loaded 6.21** 5.35** P .031 48 Table 25 Newman-Kuels Multiple Comparison Test Of Half Jump Impulse Table of Q Between Optimum ". Loaded Between .62 3.94* Optimum 3.32* Loaded * significant at .05 level (Q2= 3.03, Q3= 3.70) ** -.significant at...Oll.level (0 = 4.21, Q = 4.89) Table 26 Anova Of Total Time Source D.F. Mean Square F P Trials 2 .0008 .689 .519 Error 14 .0011 49 Table 27 Anova Of Landing Time Source D.F. Mean Square F P Trials 2 .00032 1.430 .272 Error 14 .00022 Table 28 Anova Of Jump Time Source D.F. Mean Square F P Trials 2 .0021 1.760 .208 Error :..14 .0012 Table 29 Anova of Half Jump Time Source D.F. Mean Square F P Trials 2 .0011 .715 .506 Error 14 .0015 50 Post-hoc Newman-Kuels multiple comparison tests were administered to the total, jump and half jump impulses to find where the differences existed. Tables 20, 23 and 25 show the Q values for the differences between each pair of means for each variable. For a l l three variables the impulses of the low velocity, high momentum group were significantly larger than for the two other groups who displayed no significant differences with each other. The c r i t i c a l Q values at the .05 level with 14 deg of freedom are 3.03 for 0.2 and 3.70 for Q̂ . At the .01 level the values are 4.21 for and 4.89 for Q . A multiple comparison of thev.total impulse variable gives significant differences between the loaded and the unloaded at sub-optimum groups (Q 4.71, P .05) and between the loaded and the unloaded optimum height groups (Q 4.34, P .01). For the jump impulse variable the comparison between the loaded and optimum groups is significant (Q 6.21, P .01), as is the com- parison between the loaded and unloaded sub-optimum groups (Q 5.35, P .01). The half jump impulse comparisons are significant..between the loaded and the unloaded sub-optimum groups (Q 3.94, P .05) and between the loaded and the optimum groups (Q 3.32, P .05). Discussion ...Landing forces, dip forces, landing times and landing impulses were not significantly different because the landing phases of the jumps overlapped the take-off phases. The landing impulses could not be measured because the subjects began to apply forces to decelerate the body in preparation for take-off before the landing sequence was completed. This overlap also resulted in inaccurate measuring of landing times. The fact that landing forces were not significantly different indicates that differences in landing impulses could not be measured or determined. If true measures of landing impulses were taken the overload and optimum height groups would have had the same impulse values because they landed with the same momenta and the unloaded at sub-optimum height group would have had a smaller impulse value because they landed with less momentum than the other groups (momentum is equal to impulse, mass x velocity = force x time). Jump force maximums were not significantly different and may be indica- tive of a maximum contraction force value in a l l three jumps. That i s , the subjects may have been capable only of applying a certain maximum force and they applied i t in each of the depth jump conditions, which resulted in peak reaction forces in the three conditions being equal. Again the overlap of the landing and take-off phases adversly affected the measurement of these forces. Total time on the ground during the jump averaged .325 sec for a l l conditions. Jump time and half jump time averaged .25 sec and .19 sec respectively. But the landing and take-off phase overlap resulted in the inability to measure these times accurately. There were no significant between groups differences for any of the measures. Three of the four impulse measures showed significant differences bet- ween the conditions. From Tables 20, 23 25 i t can be seen that the loaded impulses were significantly different from the two other conditions which in turn were not significantly different. However, the jump impulses and half jump impulses were hidden in the total impulses because of the over- lap between the landing and take-off phases. As a result the only true measure for comparison of the training condition jumps are the total impulses. Total impulse is a measure of landing and take-off impulses and since the total impulses of the loaded group were greater than the total impulses of the optimum height group and since their landing impulses were equal (because the landing momenta were equal and momentum = impulse), then the loaded group developed greater impulses for take-off. The unloaded at sub-optimum height group and the optimum height group showed no significant differences in the impulse measures and this may be an indication that the landing mom- enta (and therefore impulses) were not different enough to be measured. The similar total impulses indicate that the take-off impulses developed were similar for both conditions. Summary. The force tracings agreed with those reported by Asmussen and Bonde-Petersen (1974) and data obtained from them showed no significant differences between the three jump conditions in landing force, dip force, jump force, total time, landing time, jump time, half jump time, or landing impulse. Significant differences were found between the two unloaded groups when compared to the loaded group on the impulse measures and these d i f f - erences indicate that a higher average force was developed for take-off in loaded depth jumping. 53 Chapter 5 SUMMARY AND CONCLUSIONS Leg power would seem to be an extremely important requirement in jump- ing and most athletic a c t i v i t i e s . Any method which may improve leg power becomes important in training activities designed to improve performance in athletics. Plyometric d r i l l s have been credited with improving power, more specifically depth jumping has been said to improve leg power. Depth jump training i s an activity where the athlete jumps down from a height and jumps again as quickly as possible after contacting the landing surface. The benefits of this program come from improvement of the reactive a b i l i t y of the muscles of the legs. The purpose of this investigation was to study the comparative effects on vertical jump of three different depth jumping programs. The character- i s t i c s of data obtained from the force place from landing to take-off during performance of each of the depth jumping conditions were also analyzed. Thirty-eight male University of British Columbia student athletes volunteered to take part in this study. This number was reduced to 28 due to injuries and withdrawal from the study. A l l subjects were members of University teams and competed at the varsity or junior varsity level. The subjects from any one team that would be included in any one group were chosen randomly from that team. Subjects were pre, mid and posttested on the Sargeant Jump Test, Standard Depth Jump Test, Knee Extension Strength Test and Plantar Flexion Strength Test. After the study eight volunteers were tested on the Kistler force platform performing the three training depth jump conditions and the results were recorded. 54 This study was a 3 x 3 f a c t o r i a l design with repeated measures i n the second factor. The independent variables were the treatment factor with three l e v e l s and the time factor with three l e v e l s . Four dependent variables were measured: sargeant jump height, standard depth jump height, knee extension strength and plantar f l e x i o n strength. A l l groups p a r t i c i p a t e d i n a s i x week depth jumping program that was comprised of one depth jumping exercise performed at d i f f e r e n t heights f o r each group and a d i f f e r e n t loading for one group. Results of the analysis of variances showed that a l l three t r a i n i n g groups inproved i n jumping a b i l i t y and plantar f l e x i o n strength with no differences between groups i n rate of improvement and that no groups im- proved i n knee extension strength. Highly s i g n i f i c a n t c o r r e l a t i o n s were found between sargeant jump and depth jump a b i l i t y and s i g n i f i c a n t corre- l a t i o n s were found between knee extension and plantar f l e x i o n strength. The analysis of variance of data obtained from the force platform showed no s i g n i f i c a n t difference i n c h a r a c t e r i s t i c s between the three jumping conditions, except i n impulse. The loaded condition showed a s i g n i f i c a n t l y higher impulse than the other two conditions. CONCLUSIONS The following conclusions seem v a l i d based on the findings of t h i s study. 1. A s i x week depth jump t r a i n i n g program i s e f f e c t i v e i n improving v e r t i c a l jump as measured by the Sargeant and Standard Depth Jump Tests. 2. A s i x week depth jump t r a i n i n g program i s e f f e c t i v e i n improving plantar f l e x i o n strength as measured by the Plantar Flexion Strength Test. 3. Loading during a s i x week depth jump t r a i n i n g program does not adversely a f f e c t gains i n v e r t i c a l jump when compared to programs of un- 55 loaded depth jump training performed with landing momentum similar to that of the loaded program. 4. Jumping from a sub-optimum height in a six week depth jump training program does not adversely affect gains in vertical jump when compared to the results of a depth jump training program performed from optimum height. 5. An unloaded six week depth jump training program does not adversely affect strength gains when compared to the results of a loaded depth jump training program. 6. 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Translated from Theory and Practises of Physical Culture (U.S.S.R.). 59 Keohane, A.L. 1977. The E f f e c t s of a Six Week Depth Jumping Program on the V e r t i c a l .Jumping A b i l i t y of Figure Skaters. Unpublished Master Thesis, University of B r i t i s h Columbia. Knudtson, P.O. 1957. Study of the E f f e c t of Weight Training and Jumping Exercises on the Jumping A b i l i t y of G i r l Basketball Players. Unpublished M.A. Thesis, State University of Iowa. From Keohane. Komi, P.V., H. Rusko, J. Vos and V. Vihko, 1977. Anaerobic Performance Capacity i n Athletes. ACTA Physiol. Scand. 100 (1):107-114. Le, C. 1974. U.B.C. S.I.M.C.O.R.T. University of B r i t i s h Columbia Computing Centre. Lefroy, C E . 1974. Jump Training. National V o l l e y b a l l Coaches Association, Technical Jour. 1(1):102-103. Lu i t j e n s , L.L. 1969. Leg Strength and V e r t i c a l Jump of Basketball Players As Affected by Two Selected Exercise Programs Conducted Throughout the Competitive Season. Unpublished M.S. Thesis, South Dakota State University. From Keohane. Luhtanen, P. and P.V. Komi. 1978. Segmental Contribution to Forces i n V e r t i c a l Jump. European Journal of Applied Psysiology. 38(3):182-188. Marley, M. and M.G. Demeny. 1885. Locomotion Humaine, Mecahisme du saut. CR. Acad. Sc. ( P a r i s ) . 101. 489-494. From Asmussen and Bonde-Petersen. 1974. M e l v i l l Jones, G. and D.G.D. Watt. 1971. Observations on the Control of Stepping and Hopping Movements i n Man. J. Physiol. 219:709-727. M e l v i l l Jones, G. and D.G.D. Watt. 1971. Muscular Control of Landing from Unexpected F a l l s i n Man. J . of P h y s i o l . 219:729-737. Marino, F.P. 1959. Relationship of Foot Extension Strength and Jumping Exercises to V e r t i c a l Jumping Performance. Unpublished M.S. Thesis, Pennsylvania State University. 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Einbling, T. Toomsalu, J . Pross, F. McGuire, and H. Schubert. 1974. S p e c i f i c Power i n Jumping and Throwing; A Summary of Development i n Plyometric Exercises. Mod. Ath. Coach 12(5). W i l t , F. 1975. Plyometrics. A t h l e t i c Journal. Zanon, S. 1974a. Plyometric fur die Sprunge. (Plyometrics f o r Jumping.) Die Lehre der K e i c h t a t h l e t i k . 16. Referred to i n S p e c i f i c Power i n Jumping and Throwing. (Wilt et al.) Zanon, S. 1974b. Die bewusste Ausnutzung det Muskelvordehnung. (The Advantages of Prestretching.) Die Lehre der L e i c h t a t h l e t i k 42:43. Referred to i n S p e c i f i c Power i n Jumping and Throwing (Wilt et al.) 62 APPENDICES 63 Appendix A: Individual Data Pretest Data Optimum Group Subject #:•:. Sargeant Jump (in) Depth . Jump (in) Knee Extension (lb) Plantar Flexion (lb) 1 26 28 176 260 2 20 23 320 300 3 19 22 220 247 4 28 28 253 210 5 24 25 220 320 6 25 26 210 300 7 22 22 247 270 9 23 23 176 260 10 20 21 160 180 X 22.80 24.00 219.50 257.40 S.D. 2.94 - 2.58 46.47 43.45 64 Pretest Data Overload Group Subject Sargeant Depth Knee Extension Plantar # Jump Jump Strength Flexion (in) (in) (lb) (lb) 11 22 23 193 215 12 23 23 227 287 13 22 22 220 193 14 24 24 220 227 15 19 22 227 215 16 25 25 300 333 17 17 17 267 320 18 20 21 233 233 19 23 23 270 275 20 22 24 176 144 X 21.70 22.40 233.30 244.20 S.D. 2.41 2.22 36.93 58.88 65 Pretest Data Unloaded Sub-Optimum Group Subject • # Sargeant Jump (in) Depth Jump (in) Knee Extension Strength (lb) Plantar Flexion (lb) 21 28 30 265 293 22 24 22 175 172 23 24 24. 287 287 24 21 24 280 227 25 23 24 227 233 26 21 21 293 320 27 22 22 247 215 28 23 24 233 265 X 23.25 23.88 250.88 251.50 S.D. 2.25 2.75 39.26 48.48 66 Midtest Data Optimum Group Subject # Sargeant Jump (in) Standard Depth (in) Knee Extension Strength (lb) Plantar Flexion Strength (lb) 1 28 30 193 320 2 23 27 267 287 3 21 22 213 300 4: 31 31 240 287 5 28 28 213 327 6 27 27 220 340 7 24 23 280 333 8 24 25 205 393 9 22 22 193 260 10 20 21 156 280 X 24.80 25.60 218.00 .36.58 S.D. 3.55 3.53 36.58 36.29 67 Midtest Data Overload Group Subject // Sargeant J.ump (in) Standard Depth (in) Knee Extension Strength (lb) Plantar Flexion Strength (lb) 11 24 24 213 280 12 23 23 260 287 13 24 25 240 267 14 27 28 240 287 15 22 24 233 300 16 28 29 300 373 17 19 20 227 320 18 24 25 233 300 19 25 25 233 373 20 24 25 205 270 X 24.00 24.80 238.40 305.70 S.D. 2.49 2.49 26.34 38.67 68 Midtest Data Unloaded Sub-Optimum Group Subj ect Sargeant Standard Knee Extension Plantar # Jump . Depth Flexion (in) Jump Strength (in) (lb) (lb) 21 28 01 260 370 22 26 25 275 280 23 26 25 270 270 24 22 24 310 360 25 23 23 200 293 26 23 23 300 370 27 23 24 300 360 28 25 27 233 265 X 24.50 25.25 68.50 321.00 S.D. 2.07 2.66 37.37 47.88 69 Posttest Data Optimum Group Subject Sargeant Depth Knee Extension Plantar Jump Jump Flexion (in) (in) (lb) (lb) 1 28 30 187 333 2 24 27 320 320 3 21 22 205 333 4 33 33 227 327 5 28 29 205 327 6 27 29 220 350 7 25 23 267 400 8 25 25 227 393 9 22 23 187 260 10 21 21 160 273 X 25.40 26.20 220.50 331.60 S.D. 3.75 3.99 45.38 44.13 70 Posttest Data Loaded Group Subject.-. Sargeant Depth Knee Extension Plantar # Jump Jump Flexion (in) (in) (lb) (lb) 11 24 24 220 280 12 23 23 287 393 13 24 25 240 275 14 27 28 .210 300 15 23 25 227 327 16 27 29 333 400 17 20 21 253 400 18 25 24 220 327 19 26 26 267 470 20 25 26 205 275 X 24.40 25.10 246.20 344.70 S.D. 2.12 2.33 40.09 67.23 71 Posttest Data Unloaded Sub-Optimum Group Subject Sargeant Depth Knee Extension Plantar # Jump Jump Flexion (in) (in) (lb) (lb) 21 28 32 233 370 22 25 26 300 300 23 27 26 270 275 24 24 25 253 370 25 23 24 210 320 26 24 24 300 470 27 23 25 253 400 28 24 26 233 400 X 24.75 26.00 256.50 363.13 S.D. 1.83 2.56 32.20 63.07 72 Landing Force Data (lb) Subj ect Optimum Loaded . Between 1 811.27 849.9 811.27 2 811.27 811.27 811.27 3 772.64 676.06 811.27 4 753.32 811.27 811.27 5 656.74 695.38 618.11 6 811.27 772.64 791.96 7 849.90 734.01 830.59 8 849.90 811.27 791.96 X 789.54 770.22 784.71 S.D. 63.17 62.32 68.44 73 Jump Force Data (lb) Subj ect Optimum Loaded Between 1 753.32 753.32 753.32 2 791.96 791.96 772.64 3 714.69 695.38 714.69 4 598.80 676.06 637.43 5 521.53 618.11 521.53 6 714.69 695.38 695.38 7 811.27 695.38 656.74 8 811.27 791.96 772.64 X 714.69 726.77 705.03 S.D. 104.79 . . . 65.25 88.22 74 Dip Force Data (lb) Subject Optimum Loaded Between 1 154.53 367.00 212.48 2 19.32 19.32 38.63 3 115.90 0.0 289.74 4 193.16 231.79 193.16 5 309.06 212.48 270.42 6 193.16 212.48 270.42 7 386.32 270.42 309.06 8 212.48 231.79 212.48 X 197.99 193.16 224.55 S.D. 112.51 123.90 85.73 75 Total Impulse Data (lb-sec) Subject Optimum Loaded Between 1 194.32 198.19 180.99 2 168.82 166.89 156.85 3 185.43 210.74 193.16 4 209.96 220.98 194.51 5 132.12 141.39 148.35 6 151.44 159.36 150.47 7 161.10 214.41 166.12 8 161.67 184.27 163.41 X 170.61 187.03 169.23 S.D. 24.94 28.91 18.26 76 Landing Impulse Data (lb-sec) Subject Optimum Loaded Between 1 62.97 33.99 46.55 2 87.69 54.08 79.59 3 46.55 44.62 34.00 4 48.86 48.30 58.24 5 28.59 30.13 25.50 6 51.00 40.76 -32.64 7 37.48 54.47 50.22 8 46.93 39.01 43.65 X 51.26 ,43.; 17 46.30 S.D. 1.17.79 8.88 17.09 77 Jump Impulse Data (lb-sec) Subj ect Optimum Loaded Between 1 131.35 164.19 134.44 2 81.13 112.81 77.26 3 138.88 166.12 159.16 4 161.10 172.68 126.27 5 103.53 111.26 122.85 6 100.44 118.60 117.83 7 123.62 159.94 115.90 8 114.74 145.26 119.76 1 119.35 143.86 122.95 S.D. 25.00 25.81 23.29 78 Half Jump Impulse Data (lb-sec) Subject Optimum Loaded Between 1 83.06 139.08 65.67 2 38.63 53.70 45.97 3 119.76 127.49 135.21 4 146.42 154.53 111.26 5 91.94 93.88 106.24 6 76.49 91.17 86.92 7 83.06 132.12 50.22 8 87.69 112.81 92.33 X 90.88 113.10 86.73 S.D. 31.60 :.. o 32.38 31.17 79 Total Time Data (sec) Subject Optimum Loaded Between 1 .34 .34 .32 2 .22 .28 .26 3 .34 .38 .38 4 .44 .40 .34 5 .34 .30 .40 6 .28 .30 .30 7 .28 = 36 .30 8 .28 .32 .30 X .32 .34 .32 S.D. .07 .04 .05 80 Landing Time Data (sec) Subject Optimum Loading Between 1 .10 .06 .08 2 .06 .08 .10 3 .10 .08 .06 4 ...10 .08 .08 5 -..08 .06 = .06 6 .08 .06 .06 7 .06 .06 .08 8 .08 .08 .10 X .08 .07 .08 S.D. .02 .01 .02 81 Jump Time Data (sec) Subject Optimum Loaded Between 1 .24 .28 .24 2 .16 .20 .16 3 .24 .30 .32 4 .34 .32 .26 5 .26 .24 .34 6 .20 .24 .24 7 .22 .30 .22 8 .20 .24 .20 -X- .23 .27 .25 S.D. .05 .04 .06 82 Half Jump Time Data (sec) Subject Optimum Loaded Between 1 .16 .20 .12 2 .08 .10 .10 3 .20 .24 .28 4 .30 .30 .24 5 .24 .20 .30 6 .16 .18 .20 7 .16 .24 .12 8 .16 .18 .16 X .18 .21 .19 S.D. .07 .06 .08 83 Appendix B: Sample Calculations and Tables Calculation of Velocities Attained from Heights in the Training Range, s = height from floor, t = time, v =velocity, ! 2 a = gravxty, s = 2 at , v = at, 2s -therefore t = (-r-) -a 2s, I and v = a ( — ) a 2 set H = 24" a = 384 in/sec then V 1 = 384 O ^ ) * = 384 (.35355) = 135.76 in/sec velocity in feet/sec i s : 1 3 ^ 2 7 6 = 11.31 ft/sec B. Calculation of Training Heights H^ = 'optimum height, Ĥ  = loaded height and H^ = height between for unloaded sub-optimum group mo = momentum, m =-mass, v - velocity, mo - mv i f mô  = mo2 then m^v^::= m2 V2 however in the loaded condition m2:'= m̂  +..15 m̂ so iSj-Vj- = ( m^ • 15m ) v 2 v 2 = m̂ v̂ l::.15m V l 2 11.15 set H = 24" then V1 = 11.31 ft/sec 11.31 V 2 = 1.15 = 9.83 ft/sec from table 1 the training height with a velocity closest to 9.83 ft/sec is 18 in so H 2 = 18" 84 H i s the height closest to the average at and B.^ H 3 " 2 " "2 2 1 If not an even inch then the height c l o s e s t ;to and below i s taken as C. Calcu l a t i o n of Force Plate Values from the Raw Data force taken on the v e r t i c a l axis time on the h o r i z o n t a l axis 1 cm v e r t i c a l l y = 193.16 lb 1 cm h o r i z o n t a l l y = .2 sec 1 sq cm = :38.632 lb-secs i f height of landing trace = 4.2 cm landing force ="4.2 (193.16) = 811.27 lb i f trace i s 1.7 cm beginning to end on the ho r i z o n t a l axis then': t o t a l time = 1.7 (.2) = .34 sec i f the area under the curve i s 5.03 sq cm then, impulse = 5.03 (38.632) = 194.32 lb-secs Jumping force and dip force were calculated i n the same manner as.the landing force. Jump time and h a l f jump time were measured i n the same manner as t o t a l time. The distance used i n the case of jump time was from that point where 85 a v e r t i c a l l i n e from the minimum dip value intersected the h o r i z o n t a l axis, to the end of the tr a c i n g . The distance of the h a l f jump time was taken from a point on the h o r i z o n t a l d i r e c t l y below the peak jump force to the end of the tracing. Jump impulse was calculated i n the same was as t o t a l impulse but the area used was that bounded by the tracing, the h o r i z o n t a l axis and the l i n e perpendicular to the h o r i z o n t a l axis passing through the dip minimum. Half jump impulse was calculated from the area bound by trac i n g the h o r i z o n t a l axis and the l i n e perpendicular to the ho r i z o n t a l axis passing through the jump force maximum.

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