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The Effect of Depth Jumps and Weight Training on LegStrength and Vertical JumpDavid Clutch a , Mike Wilton b , Carl McGown c & G. Rex Bryce da Physical Education, South Adams High School, Berne, IN, 46711b California Polytechnic, San Luis Obispo, CA, 93401c Department of Physical Education-Sports, USAd Brigham Young University, Provo, UT, 84602Published online: 08 Feb 2013.

To cite this article: David Clutch , Mike Wilton , Carl McGown & G. Rex Bryce (1983) The Effect of Depth Jumpsand Weight Training on Leg Strength and Vertical Jump, Research Quarterly for Exercise and Sport, 54:1, 5-10, DOI:10.1080/02701367.1983.10605265

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CLUTCH, WILTON, McGOWN, BRYCE

RESEARCH QUARTERLYFOR EXERCISE AND SPORT1983, Vol. 54, No.1, pp. 5-10

The Effect of Depth Jumps and Weight TrainingOn Leg Strength and Vertical Jump

DAVID CLUTCHSouth Adams High School, Berne, Indiana

MIKE WILTONCalifornia Polytechnic, San Luis ObispoCARL McGOWN and G. REX BRYCE

Brigham Young University

In recent years, a method ofplyometrics (exercises that cause arapid lengthening of a muscle prior to contraction) called depthjumping has becomea part of the training routine ofmanyathletes. Two experiments are described in which the effectivenessof the exercises is examined. In Experiment 1, undergraduatestudents in beginning weight training classes trained with threedifferent jumping programs: (1) maximum vertical jumps, (2) 0.3m depth jumps, and (3) 0.75 m and 1.10 m depth jumps. Inaddition, all groups also lifted weights. In Experiment 2, a weighttraining class and the volleyball team at Brigham YoungUniversity-Hawaii were divided into two groups. One grouplifted weights and performed 0.75 and 1.10 m depth jumps. Theother group only lifted weights. In Experiment I, the threetraining programs resulted in increases in one repetitionmaximum (1 RM) squat strength, isometric knee extensionstrength, and in vertical jump; however, there were no significantdifferences between treatments. In Experiment 2, all groups madesignijican: increases in vertical jump, except the group ofweightlifters, who did no jumping. It was concluded that depth jumps areeffective but not more effective than a regular jumping routine.

Key words: plyometrics, depth jumps, vertical jump,weight training.

T he past decade has seen some remarkable perfor-mances in athletics. Athletes are jumping farther andhigher, runners are lowering times with monotonousregularity, the shot and discus are being heaved dis-tances thought impossible just a few years ago, andrecords in swimming are broken almost before theprevious records can be announced. Physiologically,the body has been operating the same way all this time,so how do we really account for these performances,which in many cases were deemed physically impossi-ble? Many factors have undoubtedly contributed tosuch startling performances; however, it is the conten-tion of many coaches and athletes that improvements

in training techniques and methods have been themajor contributors to modern athletic accomplish-ments (O'Shea, 1976). One very interesting trainingaddition that has been developed by coaches in theUSSR to use in preparing their athletes for variousathletic specialties is a system of plyometric exercises(Verhoshanski,1968).

Plyometric (Plyo = more, greater; metric = mea-sured quantity) exercise is based upon the belief that arapid lengthening of a muscle just prior to a contrac-tion will result in a much stronger contraction. Theadded contractile strength is believed to be due to astretching of muscle spindles involving a myotatic re-flex and resulting in an increased frequency of motorunit discharge, stimulation of other receptors, and anincreased number of activated motor units (Ver-hoshanski, 1969). Evidence indicates that plyometricexercises were systematically carried out by 1972 GoldMedal winners Valeri Borzov and Janus Lusis (Wilt,1976; Zanon, 1974).

Verhoshanski (1968) has described a plyometrictechnique called depth jumping. The procedure re-quires athletes to drop from a height and, upon land-ing, immediately perform ajumping movement. Ver-hoshanski suggested that depth jumps, like otherplyometric exercises, increase strength and nerve-reactive ability. He believes that these increases willimprove verticaljumping ability.

There is indirect experimental support for a beliefthat depth jumps will provide positive benefits. Forinstance, myotatic reflex facilitation in isometric exer-cise has been shown to increase static strength mea-surements (Awad & Kottke, 1964; Lagasse, 1974; Mor-ris, 1974; Smith, 1970). In addition, Asmussen andBonde-Petersen (1974) have shown that mechanicalenergy may be temporarily stored in the elastic com-

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ponents of a muscle by the subject's dropping from aheight of 0.40 m. In spite of this support, only limitedplyometric research has been completed.

Blattner and Noble (1979) compared a depth jump-ing group, an isokinetic training group, and a controlgroup. They found both depth jumping and isokinet-ics to be better than the control group, but there wereno differences between the two training routines.However, Blattner and Noble used only one depthjump routine, and their depth jumps were not com-bined with weight training (as recommended by Ver-hoshanski, 1969). Blattner and Noble also used sub-jects who were not involved in intercollegiate sports.Thus, this study was designed to answer two questions:(1) are certain depth jump routines, when combinedwith weight training, better than others? and (2) whateffect will depth jumps have on athletes who are al-ready engaged in training for their sports?

Experiment 1Method

SubjectsThe subjects for this study were 12 male volunteers

enrolled in a weight training class at Brigham YoungUniversity (mean age = 20.9 2.8 years, mean height= 1.79 7.5 em, mean weight = 77,7 ~ 12.4 kg).

Treatments

Three differentjumping programs were used in thestudy: (1) maximum vertical jumps, (2) 0.3 m depthjumps, and (3) 0.75 m and 1.10 m depth jumps. Theaddition of a control group that performed no jump-ing was considered; however, Blattner and Noble(1979) had found depth jumps to be more effectivethan no jumping, so it was decided to use maximumverticaljumps as the non-plyometric control. Itwas feltthis group would approximate the normal jumpingroutine many athletes experience during practice, andany benefits due to depth jumps should be over andabove their gains.

Subjects who engaged in treatment one, themaximum jumps routine, performed four sets of 10repetitions. The jumps were taken from a stationaryposition, and the subjects were instructed to pausebetween jumps to prevent a bounding effect thatwould approximate depthjumps.

Treatment two consisted of depth jumps from aheight of0.3 m. This height was recommended by Zeyl(1977) for first year depth jumpers. The subjects per-

formed the depth jumps by stepping off a box anddropping the full distance to a wrestling mat. Uponlanding, a fast, active jump was then performed. Foursets of 10 repetitions were completed during eachtraining session.

Treatment three replicated procedures in treatmenttwo, with the exception that the depth jumps wereexecuted from a height of 0.75 m and 1.10 m, as rec-ommended in the Soviet Union training system (Ver-hoshanski, 1968). Once again, four sets of 10 repe-titions were required: the first and third sets from0.75 mand the second and fourth from 1.10 m.

In all of the programs, a slow jog around a 220 mindoor track was completed after each set. Thisrhythmic 1.5 to 2 minute recovery was recommendedby Verhoshanski (1969). After completing the jump-ing program and the recovery jog, all subjects partici-pated in a weight training program, following Ver-hoshanski's recommendation that depth jumps becombined with weight training.

The weight training routine consisted of three setsof one-half squats, with four to six repetitions per set(Berger, 1962). Each repetition required the subjectsto squat until they contacted the surface of a bench;then they returned to a standing position. This aspectof the training required close supervision to ensureproper contact with the bench, and to prevent liftersfrom rebounding off the bench to assist the lift (also toprevent subjects from inadvertantly injuring backmuscles). The height of the bench was adjusted so thateach subject squatted at the same angle. The trainingworkload was increased when the subject could exe-cute six repetitions for all three sets; however, theincreased workload was not of such a magnitude as toprevent the subject from executing at least four repe-titions per set.

DesignThe experimental design selected for this study was

the Latin square change-over design (Fellingham,Bryce, & Carter, 1977). This design was chosen be-cause it allowed a powerful test of treatment differ-ences even with a small number of subjects. In thisdesign, each subject received each treatment for onetime period, each treatment was applied to the samenumber ofsubjects during each treatment period, andeach treatment followed every other treatment thesame number of times in the experiment. Thus, thedesign allowed each subject to act as his own control.This provided, in effect, a covariate measured at eachtime period. All tests were made at the 0.05 level ofsignificance.

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With three treatments, there are six possible se-quences (1,2,3; 1,3,2; 2,1,3; 2,3,1; 3,1,2; 3,2,1), and eachsubject was assigned a randomly selected treatmentsequence. There were two subjects in each of the sixsequences. Each treatment sequence lasted fourweeks, and training sessions were held twice a week.

Three weeks ofweight training were completed be-fore beginning any jumping. This period was used tominimize between-subject variance due to differencesin muscle soreness and speed of skill acquisition notrelated to actual strength gains. A pretest of the de-pendent variables was conducted at the end of thestabilization period.

Test AdministrationLeg strength and vertical jump were pretested dur-

ing the sixth training session of the stabilization periodand at the conclusion of each four week treatmentsequence. Leg strength was evaluated by determiningthe weight with which a subject could do one squat (1RM), and by measuring the force of a maximumisometric knee extension performed at an angle of125.

The 1 RM procedure required the lifter to performwith the maximum weight that he felt he could managefor one lift. Weight was added or taken off the bar in 5or 10 pound increments, depending upon the ease ordifficulty of the successful or unsuccessful attempt.The rest interval between maximum lifts varied ac-cording to each subject's perceived readiness to at-tempt a heavier lift. Genov (1970) has shown that thismethod of optimal mobilization readiness yields thebest results in the achievement ofsuccessful maximurnlifts, and a pretest using this method in another weighttraining class had shown the test-on-one-day retest-on-another-day reliability to be 0.94.

Cable tension tests were used to record the force ofmaximum isometric knee contraction. The tests wereconducted on a strength testing table modeled afterrecommendations by Clarke (1950). Each subject wasinstructed to sit on the table with his hands behind hiships and his elbows extended. A length of 2 inch webbelting was secured to the subject's legjust superior tothe ankle and connected with "D" rings to a BristolDynamaster strain gauge. A goniometer was used tomeasure an angle of 125 degrees at the knee of thesubject; an adjustable chain was used to hook the straingauge to the table. The subject then exerted amaximum force; two trials were conducted on eachleg, alternating between legs to reduce fatigue. Themean score of the four trials was recorded for statisti-cal analysis (Henry, 1967; Baumgartner, 1974).

A pressure platform that measured the time be-tween takeoff and landing was used to test verticaljump. The subjects stood on the platform andjumpedas high as possible, trying to hit a tape hanging abovethem. Leaving the platform activated a timer; landingon the platform stopped the timer. Time was mea-sured in 0.001 seconds. Ten trials were given, withapproximately 2.5 to 3 minutes between every twojumps. Henry (1942) found this procedure to have areliability of0.97. The mean ofthe 10 trials was used inthe analysis.

ResultsIntraclass correlation was used to estimate the relia-

bility of the leg extension and vertical jump measures.This analysis showed the scores to be very reliable, withthe pretest score for verticaljump equal to 0.99, rightknee extension equal to 0.89, and left knee extensionequal to 0.92. There were three posttest scores (oneafter each treatment); the reliabilities for verticaljumpwere all 0.99, for right knee extension 0.87,0.86,0.85,and for the left knee extension 0.86, 0.93,0.91.

As might be expected with progressive resistanceexercise, there were significant gains in 1 RM, F (1,10)= 68.91, P< .001, knee extension, F (1,10)= 35.92, P.05, for knee extension F (2,18) = 0.73,p > .05, and forverticaljump, F (2,22) = 0.62,p > .05. The mean gainsfor each measure for each treatment are presented inTable 1.

Another test of importance was the test for carry-over effects. In each instance the calculation revealedno significant carry-over effects: for 1 RM, F (2,14) =0.75, P> .05, knee extension, F (2,14) = 0.38, P> .05,and vertical jump, F (2,14) = 0.25, P> .05. Thus, theeffects ofthe three training routines were not additive.

DiscussionThe results of this study seem to indicate that depth

jumps, when combined with weight training, are nomore effective than a program of regular maximumjumps. Also, the two different types of depth jumproutines resulted in comparable gains. It is interestingto note that the subjects made an average verticaljumpgain of 8.40 em. This finding, while not surprising,shows that a program of strength training, combinedwith a program of almost any kind ofjumping, can bean effective means ofincreasing verticaljump.

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Table 1(Experiment 1)

Gains in Strength and Vertical Jump'For Each Treatment

Knee VerticalTreatment 1 RMb Extensionb JumpcVertical

Jumps 18.56 (7.19) 4.60 (5.84) 2.08 (3.23)0.30m

depth jumps 10.59 (5.84) 4.49 (6.36) 3.35 (2.03)0.75-1.10 m

depth jumps 14.58 (7.21) 6.00 (5.95) 2.97 (3.56)Total Gain 43.73 15.09 8.40'Standard deviations in parenthesesbScores are in kilogramscScores are in centimeters

There appear to be two main possibilities for thefailure of this research to support depth jumps. One isthat these plyometric exercises did not create thestretch effect required to produce an extra strengthstimulus. During depth jumps, the downward forcemay merely have stretched the muscles; possibly aGolgi tendon reflex was elicited, inhibiting instead offacilitating a myotatic reflex from the muscle spindles,which was needed to increase strength (Awad &Kottke, 1964; Lagasse, 1974; Morris, 1974; Smith,1970).

The other possibility is that plyometrics are of valueprimarily to trained athletes. The subjects who en-gaged in this study and in the study by Blattner andNoble (1979) were beginning weight lifters, not thehighly-trained athletes referred to in the Europeanliterature (Wilt, 1976; Zanon, 1974). Thus Experiment2 was an attempt to involve competitive athletes in aprogram ofdepthjumping.

Experiment 2Method

SubjectsThe subjects for this study were 16 members of a

weight training class and 16 members of the men'svolleyball team at Brigham Young University-Hawaii.Their mean age was 21.2 2.9years, mean height 183 9.2em, and mean weight 87.5 14.7 kg.

ProcedureThe members of both groups were randomly as-

signed to one of two treatments. Subjects in treatmentone trained with a weight training and depthjumpingprogram, while those in treatment two trained with

weights, but performed no depth jumping. Theweight training exercises consisted of the dead lift,bench press, and parallel squat. Three sets ofsix repe-titions were performed in each exercise. Initial loadswere calculated at 80% ofeach subject's one repetitionmaximum (1 RM). Resistance was increased in eachexercise when more than six repetitions could be exe-cuted in the third set. The depth jumping programwas the program recommended by Verhoshanski(1969) for athletes. This program was comprised offour setsoflOjumps, two sets from 0.75 m and two setsfrom 1.10 m. The same program was used in treatmenttwo in Experiment 1. The subjects lifted, and thosedoing depthjumpsjumped twice a week for 16 weeks.Two times a week was chosen, as it is the trainingfrequency recommended by Verhoshanski (1969). Inaddition, the volleyball team practiced volleyball fivedays a week for 2.5 hours each day.

A specially constructed apparatus was used to mea-sure verticaljump. Itconsistedofa 137 em long by 4cmthick by 13 em wide box with 0.1 ern holes drilledthrough the middle of the front panel at staggered1.27 em intervals. The holes contained 0.80 em widedowels 6 ern long. The device was clamped to the sideof a basketball backboard in the gymnasium so that arange of259 ern to 381 em could be measured. Beforetesting, the subjects engaged in 5 minutes ofjoggingand stretching. The subject to be tested then assumed aposition beneath the measuring apparatus andjumped and reached, pushing the highest dowel hecould. There was one trial day of four jumps, then onthe test day two practice jumps and four recordedjumps, with the average of the four scores used as thecriterion measure. The subjects were pretested duringthe first week and posttested during the last week.

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Table 2(Experiment 2)

Pre-, Posttest and Adjusted Gain scores-For Vertical Jumpb

Weight TrainingClass

WT+ DJAdjusted

Pre Post Gain Pre56.29 60.17 3.73 50.93(7.75) (7.49) (0.81) (10.67)

Volleyball TeamWT WT+ DJ WT

Adjusted Adjusted AdjustedPost Gain Pre Post Gain Pre Post Gain51.64 -0.11 60.40 63.25 3.21 62.61 66.24 4.25(9.40) (0.87) (9.68) (8.38) (0.82) (7.01) (6.88) (0.84)

aStandard deviations in parenthesesbScores are in centimetersWT = Weight trainingDJ = Depth jumping

ResultsIntraclass correlation was used to estimate the relia-

bility of the pre- and posttest verticaljump scores. Thepretest reliability was 0.994, the pos~test0.995..

Analysis of variance on the gam scores with thepretest as a covariate, a method recommended byHendrix, Carter, and Hintze (1979), was used toanalyze the data. All differences were tested at the .05level. The pre-, posttest and adjusted gain scores arepresented in Table 2. "

The analysis produced some mterestmg results:there were significant gains in verticaljump, F (1,27) =12.56, P< .001; the volleyball team gained more thanthe weight training class, F (1,27) = 4.69, P< .05; butdepth jumps were not more effective than no depthjumps, F (1,27) = 2.99, P< .05. However, there was a

significant interaction between the groups and thetreatment, F (1,27) = 8.77, P< .01. The interaction isdisplayed in Figure 1.

Analysis of the interaction, using the Boneferoni(Miller, 1966) method, indicated that the group ofweight lifters who did no jumping were significantlydifferent from the other groups. There were no othersignificant differences. Thus it appe~rs t~at depthjumps were helpful to the group ofweIg~tlifters whohad no other jumping stimulus. The active volleyballplayers who were involved in depth jumping andweight training made gains similar to those of thegroup of players who were only weight training. Itseems that depthjumps are useful for athletes who aredoing no other jumping, but they add nothing o~erand above that which is obtained from normal practicewhere a good deal ofjumping occurs.

Figure 1-Adjusted vertical jump gain scores for theweight training class and the VOlleyball team.

o = weight training class

en 4.50....

Q)- 4.00Q)E:;::; 4,50cQ)

3.00o.~ 3.50enQ)

2.00....0o

2.50(J)c 1.00'ffi

C!J1.50

"CQ)-

0en:J'5' -.50-c = volleyball team

DepthJumps

No DepthJumps

DiscussionThe results of Experiments 1 and 2 are very similar.

In Experiment 1it was found that a program of?,ormalverticaljumps and weight training produced gams thatwere comparable to two different programs of depthjumps and weight training. In Experiment 2 depthjumps did not producejump increases beyond that?fajumping routine that was a normal part of practice.Thus, depth jumps do not appear to be better thanother more common training methods. However, thesubjects in this study reported that they enj.oyed doi~gdepth jumps, and so for those athlete~ mvolv~d.mintense training, depthjumps could provide a trammgtechnique that is effective in producingjump increasesand would allow for a variation from the normal grind.

Finally, it should be mentioned that Bosco (1981) hasdemonstrated that a jump training program usingexercises similar to depth jumps increased the elastic

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potential and the tolerance for stretch loads in the legextensor muscles of the Finnish national volleyballteam. Bosco suggests that bouncing training influ-ences the contractile and elastic properties of the mus-cles and the proprioceptive feedback mechanisms. Butthe improvement was not obtained until 18 months oftraining. His data would suggest that for depthjumpsto be effective, they must be utilized for much longerthan the 16 weeks used in this study. Nevertheless, assuggested by the results ofthis study, our belief is that aprogram of depth jumping adds nothing extra to aprogram that already includes weight training and avariety ofotherjumpingexercises.

ReferencesAsmussen, E., & Bonde-Peterson, R Storage of elastic en-

ergy in skeletal muscles in man. Acta Physiologica Scan-dinavia, 1974,91, 385-392.

Awad, E. A., & Kottke, F.]. Effectiveness of myotatic reflexfacilitation in augmenting rate of increase of muscularstrength due to brief maximal exercise. Archives ofPhysi-cal Medicine and Rehabilitation, 1964,45, 32-39.

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Blattner, S. E., & Noble, L. Relative effects of isokinetic andplyometric training on vertical jumping performance.Research Quarterly, 1979,50, 583-588.

Bosco, C. New tests for the measurement ofanaerobic capac-ity in jumping and leg extensor muscle elasticity. journalof The National Volleyball Coaches Association, 1981, 2,5-12.

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its formation. In G. S. Kenyon (Ed.), Contemporary Psy-chologyofSport. Chicago: The Athletic Institute, 1970.

Hendrix, L.]., Carter, M. W., & Hintze,]. L. A comparisonof five statistical methods for analyzing pretest-posttestdesigns. journal of Experimental Education, 1979, 47,96-102.

Henry, F. The practice and fatigue effects in the Sargent test.Research Quarterly, 1942,13,17-29.

Henry, F. "Best" versus "average" individual scores. ResearchQuarwrry,1967,38,317-320.

Lagasse, P. P. Muscle strength: ipsilateral and contralateraleffects of super-imposed stretch. Archives of PhysicalMedicine and Rehabilitation, 1974,55, 305-310.

Miller, R G. Simultaneous statistical inference. New York:McGraw-Hill, 1966.

Morris, A. F. Myotatic reflex effects in bilateral reciprocal legstrength. American Corrective Therapy journal, 1974, 28,24-29.

O'Shea,]. P. Scientific principles and methods of strength fitness.Reading, MA: Addison-Wesley, 1976.

Smith, L. E. Facilitatory effects of myotatic stretch trainingupon leg strength and contralateral transfer. Americanjournal ofPhysical Medicine, 1970,49,132-141.

Verhoshanski, Y. Perspectives in the improvement ofspeed-strength ofjumpers. YessisReview ofSoviet PhysicalEducation and Sports, 1968,3, 28-34.

Verhoshanski, Y. Are depth jumps useful? Yessis Review ofSoviet Physical Education and Sports, 1969,4,75-78.

Wilt, F. Plyometrics. Track Technique, 1976,63, 1992.Zanon, S. S. Specific power in jumping and throwing. Mod-

ern Athlete and Coach, 1974,12, 7-10.Zeyl, G. DepthJumping. Track Technique, 1977,63,2179.

Submitted: April 13, 1981Accepted: April 26, 1982

David Clutch isa teacherofphysicaleducationat South AdamsHigh School,Berne, IN 46711. Mike Wilton is thecoachofwomen'svolleyball at Califor-nia Polytechnic, San Luis Obispo, CA 93401. CarlMcGown isa professor intheDepartmentof PhysicalEducation-Sportsand G. Rex Bryceaprofessor ofStatistics at Brigham Young University, Provo, UT 84602.

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