Relationship of the Stretch-Shortening Cycle to Sprint Performance in Trained Female Athletes

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Journal of Strength and Conditioning Research, 2001, 15(3), 326331q 2001 National Strength & Conditioning Association

Relationship of the Stretch-Shortening Cycle toSprint Performance in Trained Female Athletes

LIAM HENNESSY1 AND JAMES KILTY2

1The Fitness Department, Irish Rugby Football Union, Ballsbridge, Dublin, Ireland; 2The Athletic Association ofIreland, Glasnevin, Dublin, Ireland.

ABSTRACT

This study assessed the relationship of long and shortstretch-shortening cycle test scores to sprint performances intrained female athletes. Seventeen trained, female, highschool, competitive sprinters completed the following tests:countermovement jump for vertical distance (CMJ), bouncedrop jump for height with minimum ground contact time(BDJ index), and ground contact time (GCT) during the BDJand a 5-step bound (5B) test. Group mean and SD valueswere as follows: height, 167.7 6 3.7 cm; body mass, 59.9 67.2 kg; and percentage of body fat (PF), 20.3 6 1.8%. Sprintperformances at 30-, 100-, and 300-m distances were as-sessed. Stretch-shortening cycle performance and sprint re-sults (mean 6 SD) were as follows: CMJ, 33.8 6 3.8 cm; BDJindex, 166.7 6 24.7 cm/s; 5B test, 10.98 6 0.76 m; 30-msprint, 4.58 6 0.17 seconds; 100-m sprint, 12.9 6 0.61 sec-onds; and 300-m sprint, 45.03 6 2.94 seconds. Correlationsindicated that no relationship existed between PF and thedependent sprint variables. Significant correlations (p , 0.05)existed between CMJ and 30-m (r 5 20.60), 100-m (r 520.64), and 300-m (r 5 20.55) sprint times; BDJ index and30-m (r 5 20.79) and 100-m (r 5 20.75) sprint times; and5B test and 300-m sprint time (r 5 20.54). Multiple regres-sion analysis found significant T values for BDJ index with30- and 100-m sprints and CMJ and PF with 300 m. Resultsindicated that the BDJ index and CMJ tests were significantlyrelated to sprint performances in female athletes.

Key Words: countermovement jump, bounce dropjump index, sprinting

Reference Data: Hennessy, L., and J. Kilty. Relationshipof the stretch-shortening cycle to sprint performancein trained female athletes. J. Strength Cond. Res. 15(3):326331. 2001.

Introduction

Laboratory-based tests using isokinetic, dynamom-etry, and force plate devices and field-based jump-ing tests are used to assess the leg strength and powerof athletes (1, 3, 5, 14, 15, 19, 20). In general, laboratorytests are not easily accessed or readily available for useand are thus impractical for many coaches. Field-based

tests are more frequently used by coaches to monitorathletic progress (912, 19). The field-based tests mostcommonly used include the following: the jump-and-reach test for vertical distance, the countermovementjump for vertical distance (CMJ), the bounce dropjump for height (BDJ) and hopping or bounding fordistance (5, 7, 10, 15).

These performance tests seem to demonstrate ahigh degree of specificity to sprint running. In partic-ular, the support phase during the jumping actionmimics the eccentric-concentric contractions of the legextensor muscles during the sprint action. This move-ment is commonly termed a stretch-shortening cycle(SSC) action, and it results in a more forceful concen-tric contraction compared with a normal concentriccontraction without a prior eccentric action. Althoughthe precise mechanism responsible for this enhancedforce is unclear, a number of interactive mechanismshave been suggested, namely the use of stored elasticenergy, the contribution of reflex recruitment of addi-tional motor units, increased rate coding, and en-hanced potentiation in the extensor muscles beforeground contact (15).

The metabolic pathway associated with completingshort sprint distances taxes the phosphagen system,whereas longer sprints involve a significant contribu-tion from anaerobic glycolysis (9). Locatelli (10) re-ported a strong relationship between anaerobic gly-colysis as determined by blood lactate levels during100- and 200-m sprint races and the power calculatedfrom a series of SSC actions. This suggests that the SSCaction may be more closely related to performance ina long sprint compared with a short sprint. Similarly,a close relationship has been demonstrated betweenthe power produced during SSC actions and the main-tenance of maximal velocity during 100- and 200-msprinting (9, 10).

Schmidtbleicher (15) has considered the SSC actionas long (.250 milliseconds) and short (,250 millisec-onds) based on the ground contact time (GCT) of theSSC action. The CMJ may be considered a long SSCaction, whereas the BDJ can be classified as a short

Stretch-Shortening Cycle and Sprint Performance 327

SSC action because of its relatively short foot supportphase. Further, it has been demonstrated that the cor-relation between the CMJ and BDJ is low, indicatingthat both tests are measuring different movementcharacteristics (7, 15, 23). Young et al. (23) proposed avariation in the technique of executing the BDJ as pro-posed by Schmidtbleicher (15). The authors used a BDJtechnique that required subjects to jump for maximumheight with an additional emphasis on minimizingGCT (BDJ index). The test result was presented as afunction of the height achieved during the BDJ dividedby the GCT. The authors suggested that the test maybe appropriate for examining the short SSC and highload action common to plyometric exercises and move-ments (23).

Significant relationships have been reported be-tween the CMJ and sprinting performance over shortdistances (5, 11, 22). Additionally, Nesser et al. (13)reported a significant correlation between a 5-stepjump and a 40-m sprint in young active men. However,the relationships between the BDJ test and more spe-cifically the BDJ index and sprint performances havenot been well addressed in the literature. Additionally,although numerous studies have investigated the re-lationship between performance tests and sprint ca-pability in active male athletes (2, 4, 13, 22), few if anyhave examined the relationship in well-trained femaleathletes. It is an open question as to whether femaleathletes display similar relationships between jumpperformance tests and sprint capability as reported foractive male subjects.

The primary purpose of the present study was,therefore, to extend the examination of the relationshipbetween commonly used SSC actions and sprint per-formances over different distances in well-trained fe-male athletes. A secondary purpose was to examinethe relationship between measurements of long andshort SSC actions.

MethodsSubjectsSeventeen women nationally ranked in sprint and hur-dle events participated in this study. All athletes com-peted in both sprint and hurdles events during thecompetitive season. Informed consent was granted,and all subjects had completed at least 2 years of spe-cific sprint training before participating in this study.Mean 6 SD age was 17.6 6 2.2 years, height was 167.76 3.7 cm, body mass was 59.9 6 7.2 kg, and percent-age of fat (PF) was 20.3 6 1.8 %.

Testing ProceduresAll tests were completed in 2 days as part of a regulartesting program. During day 1, the following testswere completed: height, body mass, and PF; CMJ forvertical distance (in centimeters), BDJ (from 30 cm)vertical distance (in centimeters), BDJ index (in centi-

meters/second), and a 5-step bound (5B) horizontaldistance (in meters). Performance testing for 30- and100-m distances was completed on day 1, whereas the300-m sprint was completed on day 2. These distanceswere selected because they were part of a battery ofsprint distances used by the coach to monitor perfor-mance changes throughout the training and competi-tion year. The 30-m sprint test was regularly used toassess the acceleration phase of the sprint for the 100-m sprinters, whereas the 300-m sprint was used tomonitor speed endurance for the 200-m sprinters. Ad-ditionally, training facility characteristics restricted in-door sprinting testing distances to 30-m, whereas the300-m sprint was selected because it was a featuresprint event within the athletes local geographical re-gion. The tests were completed in the order outlined.Although it is possible that an order effect occurred,the athletes were experienced at participating in sev-eral rounds of competition during track-and-fieldmeetings that lasted 2 or more days. Additionally, carewas taken to allow sufficient rest between all tests tolimit the effects of fatigue on subsequent tests.

Test DetailsHeight was measured using a wall-mounted stadi-ometer (Seca) recorded to the nearest centimeter. Bodymass was measured to the nearest 0.1 kg using a med-ical scale. Percentage of body fat was estimated usingthe skinfold method of Jackson et al. (8). Subsequentconversion of body density to PF was completed usingthe equation of Siri (16).

Countermovement JumpThe CMJ tested the long SSC action. The CMJ and BDJindex tests were performed using an electronic contactmat system (Newtest, Oulu, Finland). Height achievedwas determined from flight time. During the CMJ, thesubject was instructed to rest her hands on her hipswhile performing a downward movement followed bya maximum effort vertical jump. All subjects were in-structed to land in an upright position and to bendthe knees following landing. The best of 4 trials wasreported.

BDJ TestThe BDJ index test assessed the short SSC action. Dur-ing the BDJ index test, the subject was instructed todrop from a 30-cm height and to complete a maximumeffort rebound jump. The primary goal of this test wasto attain maximum jump height and minimum GCT.Further instructions stressed the importance of land-ing from a jump in a fully extended position, com-pleting each effort without heels contacting the matwhile the subjects hands remained on her hipsthroughout the test. Additionally, video analysis wasused to determine if heel contact was made during thedrop jump. The best jump height attained with aground contact of less than 250 milliseconds and with-

328 Hennessy and Kilty

Table 1. Values for predictor variables and performancevariables tested.*

Variables

Predictor variablesCMJ (cm)GCT (s)BDJ index (cm/s)5B test (m)

33.8 6 3.80.185 6 0.018166.7 6 24.710.98 6 0.76

Performance variables30-m sprint (s)100-m sprint (s)300-m sprint (s)

4.58 6 0.1712.90 6 0.6145.03 6 2.94

* Values are mean 6 SD; n 5 17. CMJ 5 countermovementjump for vertical distance; GCT 5 ground contact time; BDJindex 5 bounce drop jump for height with minimum GCT;5B 5 5-step bound.

Table 2. Correlations between body composition, stretch-shortening cycle tests, and sprint performance tests.

Variable 2 3 4 5 6 7 8

1. PF2. CMJ (cm)3. GCT (s)4. BDJ index (cm/s)

20.56* 20.510.43

20.230.62*

20.21

20.350.54*

20.060.54*

0.2220.60*20.1020.79*

0.1520.64*20.0620.75*

20.0620.55*20.0820.49

5. 5B (m)6. 30-m sprint (s)7. 100-m sprint (s)8. 300-m sprint (s)

20.43 20.480.93*

20.54*0.75*0.86*

n 5 17. PF 5 percentage of body fat; CMJ 5 countermovement jump for vertical distance; GCT 5 ground contact time;BDJ index 5 bounce drop jump for height with minimum GCT; 5B 5 5-step bound.

* p , 0.05.

out heel contact was recorded. The jump height at-tained was divided by the contact time, and this cal-culation was used for analysis. This is reported as theBDJ index. The best of 4 trials for this test was record-ed.

5B TestA 5B test, which consisted of 5 dynamic horizontalbounds, was used to assess repetitive SSC muscularcontractions. Each subject started with both feet to-gether and completed 5 consecutive bounds using al-ternate feet. The fifth contact was completed with bothfeet landing in a sand pit. The best 5B horizontal dis-tance of the 4 trials was recorded. Subjects were wellacquainted with all performance tests.

Sprint TestsSprint times were recorded for 30-, 100-, and 300-mdistances. The 30-m sprint test was conducted indoorson a tartan running surface. The 100- and 300-m sprinttests were completed outdoors on a similar runningsurface. All outdoor tests were completed with a wind

velocity less than 2 ms21. For all sprint tests, the sub-ject started using a crouch start and commencedsprinting on their own initiation. An electronic timingdevice with a touch pad start was used (Brower, SaltLake City, UT). Infrared beams were positioned at thesprint distance to be measured. Two trials were al-lowed at each sprint distance, with the best effort re-corded; times were reported to the nearest one hun-dredth of a second.

Statistical AnalysesPearson product moment correlations were used to es-tablish relationships among variables. Forward step-wise multiple regression analysis was completed foreach dependent sprint variable using PF and perfor-mance tests as independent variables. The use of sev-eral predictor variables is not justified for the limitednumber of subjects used in the present study. How-ever, 3 predictor variables were selected for regressionanalysis based on the theoretical evidence in the lit-erature cited earlier. All data were analyzed using theStatistica for Windows statistical package (18). Signif-icance for all tests was set at the 0.05 a level.

ResultsCorrelational AnalysisMean and SDs of performance tests and sprint vari-ables are presented in Table 1. Correlations among allvariables tested are shown in Table 2. A number ofsignificant correlations existed at the 0.05 level of con-fidence. Both PF and CMJ demonstrated a significantinverse relationship (r 5 20.56, p , 0.05). Among theSSC performance variables, the closest relationshipwas between the BDJ index and CMJ (r 5 0.62, p ,0.05). The CMJ displayed a relatively consistent rela-tionship across 30-, 100- and 300-m sprints (20.60,20.64, and 20.55; p , 0.05, respectively). The BDJ in-dex displayed relationships of 20.79 (p , 0.05), 20.75(p , 0.05), and 20.49 (nonsignificant) across 30-, 100-,and 300-m sprints, respectively. The 5B test displayed


relationships of 20.43 (nonsignificant), 20.48 (nonsig-nificant), and 20.54 (p , 0.05) across 30-, 100-, and300-m sprints, respectively.

Multiple Regression Analysis30-m Sprint. Forward stepwise multiple regressionidentified 2 variables that accounted for 70.5% of thevariance in the 30-m sprint (multiple R 5 0.839, R2 50.705, F 5 14.31, standard error of the estimate [SEE]5 0.0841, p , 0.01). Performance could be explainedby the following equation:

30-m time (in seconds) 5 5.83

2 0.00523 (BDJ index, in centimeters per second)

2 2.08 (GCT, in seconds).

A significant T-value of 0.0001 was noted for theBDJ index. The BDJ index alone accounted for 63% ofthe variance.

100-m Sprint. For the 100-m sprint, 2 predictor var-iables accounted for 61% of the variance (multiple R5 0.78, R2 5 0.611, F 5 9.43, SEE 5 0.417, p , 0.01).Performance could be explained by the followingequation:


2 0.01497 (BDJ index, in centimeters per second)

2 0.04833 (CMJ, in centimeters).

A significant T-value of 0.0298 was recorded for theBDJ index, explaining 55.7% of the total variance iden-tified with an additional 5.3% explained by the CMJ.

300-m Sprint. For the 300-m sprint, 3 predictor var-iables were used to account for 59.3% of the variance(multiple R 5 0.77, R2 5 0.593, F 5 5.34, SEE 5 2.117,p , 0.05). Performance could be explained by the fol-lowing equation:


2 0.5098 (CMJ, in centimeters) 2 0.8795 (PF)

2 1.49061 (5B test, in meters).

The CMJ accounted for 30% of the variance withthe PF and 5B test variables, contributing 19.3% and10%, respectively, to the total variance explained. Sig-nificant T-values of 0.0281 and 0.0354 were noted forCMJ and PF, respectively.

The regression coefficient of 0.00523 for the BDJindex of the 30-m sprint time can be interpreted tomean that the best prediction of an athletes 30-msprint time would decrease by 0.005 seconds when theBDJ index increases by 1 cm/s unit. A theoretical im-provement of 0.014 seconds in the 100-m sprint timeis predicted when the BDJ index increases by 1 cm/sunit. Similarly the regression coefficient of 0.5098 forthe CMJ can be interpreted to suggest a 0.5-secondimprovement in 300-m sprint time for a 1-cm increasein CMJ vertical distance.

Discussion

The primary purpose of this study was to assess therelationship between long and short SSC tests, whichare commonly used by coaches during performancemonitoring, and sprint capability for different distanc-es in female athletes. A secondary purpose was to ex-amine the relationships among the BDJ index, a testrepresentative of a short SSC action; the CMJ, a testrepresentative of a long SSC action; and the 5B test.

The relatively low common variance (38%) betweenthe BDJ index and CMJ in the present study is inagreement with the findings from other studies (7, 15,23). The shared variance between the BDJ index and5B test was 29%, whereas the shared variance betweenthe CMJ and the 5B test was similar. These findingsindicate that there is little commonality among thetests, and as such all 3 tests may be assessing distinctperformance characteristics in female sprinters.Schmidtbleicher (15) has noted that the long SSC ac-tion is characterized by large angular displacements ofthe hip, knee, and ankle joints, and the total GCT forthis SSC action is more than 250 milliseconds. In con-trast, the short SSC action is characterized by smallangular displacements in the cited joints and lasts100250 milliseconds. The CMJ typically is character-ized by large angular displacements in the lowerlimbs, whereas the BDJ index test requires the subjectto limit lower limb angular displacement and GCT.The 5B test is characterized by a combination of largeand small angular displacements in the lower limbs.

Significant relationships were reported betweenlong and short SSC actions and sprint performances.The CMJ correlated significantly with all sprint dis-tances up to 300 m. The BDJ index correlated signifi-cantly with 30- and 100-m sprint performances. Pre-vious studies have reported significant relationshipsbetween the CMJ and short sprint performances foractive men (5, 13, 22). Bosco et al. (5) reported a re-lationship of r 5 0.93 (p , 0.01) between the CMJ and30-m sprint. The strong relationship in that study mayhave been influenced by the inclusion of both male andfemale athletes within the subject sample population.This is likely to have inflated the range of CMJ valuesrecorded and in turn may have contributed to a highcorrelation. The female athletes in the present studydisplayed a lower correlation, yet the relationships ob-served support the use of the CMJ as an appropriatetest for assessing sprint performance in female sprint-ers.

Regression analysis for the 30-m sprint identifiedthe BDJ index as the primary variable related to sprintperformance. The variance explained by the BDJ indexand GCT variables was 70.5% and demonstrates theirrelationship to sprint performance for this sprint dis-tance. The GCT contributed only 7.3% to the overallvariance, indicating that its relative importance seems

330 Hennessy and Kilty

to be low compared with that of the BDJ index. Berget al. (2) reported an equation that included 9 variablesand accounted for 98.5% of the variance in a 30-msprint. However, a greater number of independent var-iables were included in the regression analysis com-pared with the present study. Nesser et al. (13) re-ported an equation using 3 variables, which accountedfor 82.7% of the variance in a 40-m sprint. The vari-ables included a 5-step jump and knee and ankle iso-kinetic flexion strength. The 5B test used in the presentstudy was similar to the performance test used byNesser et al. (13); however, in the present study the 5Btest demonstrated an inverse but insignificant relation-ship with the 30-m sprint time.

The 100-m sprint regression equation containedvariables for the BDJ index and CMJ, accounting for61% of the sprint variance. The contribution of the BDJindex was 55%, which suggests that it is a relativelyimportant variable in accounting for 100-m sprint per-formance. The addition of the CMJ to the equation con-tributes to the variance explained. This suggests thatboth short and long SSC actions are related to 100-msprint times in female athletes.

The variables that account for the explained vari-ance of 59.3% in the 300-m sprint time were the CMJ,PF, and 5B tests. The CMJ contributed 30% and indi-cates its relative contribution to this sprint test. Theaddition of PF to the equation contributed 19.3% tothe explained variance. Other authors have demon-strated an inverse relationship between body fat andanaerobic power performances (17, 21). However, therelationship demonstrated between PF and all sprintperformances in the present study is weak. This maybe as a result of the relatively low spread of PF levelsfor the subjects in this study. The 5B test contributedan additional 10% to the explained variance of the 300-m sprint time. Given that the 5B test displayed littlecommonality with the CMJ and BDJ index, the inclu-sion of this variable in the equation demonstrates themultifactorial nature of sprinting performance.

The relatively low total variance explained by theindependent variables examined in this study acrossall sprint distances indicates that other factors not ac-counted for within this study are important in ex-plaining the factors associated with successful sprintperformances. Previous studies have identified anthro-pometric dimensions (17, 21), high strength levels atlow and high velocities (6, 13), fiber type distribution(5, 6), and hormonal status (4) as factors associatedwith proficiency in sprint running. In addition, therole of the phosphagen energy system in short-term(,5 seconds) sprint performance has been previouslydemonstrated (9). Lacour (9) also noted that no cor-relation existed between blood lactate levels and per-formance at distances less than 100 m, indicating thatthe role of anaerobic glycolysis is not prominent dur-ing short sprint events. In contrast, for distances great-

er than 100 m, the strong relationship noted betweenblood lactate levels and the maintenance of maximalvelocity in sprint running demonstrates the impor-tance of anaerobic glycolysis in sprint performance atthe longer distances (9, 10). No measurement of an-aerobic glycolysis was made in the present study.Therefore, it is not possible to examine its contributionto sprint performance in this group of female athletes.This may partially help to explain the lower power ofprediction of the regression equations with increasingsprint distance in this study.

Results from this study suggest that an increase inthe performance of the BDJ index may, theoretically,effect a 0.005- and 0.014-second improvement in 30-and 100-m sprint times, respectively. Effecting an in-crease of 1 cm in the CMJ may improve 300-m sprintperformance by 0.5 seconds. Such improvements insprint times may be considered significant in compet-itive athletic terms. However, further investigation isrequired to establish the validity of such suggestions,given the limitations of the small number of subjectsused in the present study.

In summary, results from this study indicate thatboth long and short SSC actions, as demonstrated bythe CMJ for vertical distance, the 5B test, and the BDJindex, help explain part of the relationship betweenperformance characteristics and proficiency in sprint-ing in female athletes. It is recommended that futureresearch into the factors that contribute to sprint per-formance examine metabolic and hormonal parame-ters in addition to field-based speed-strength tests asthe independent variables of study using a greaternumber of subjects. In addition, further examinationinto the impact of improvements in the long and shortSSC tests on sprint performance would be of interest.

Practical ApplicationsThe results of this study help to explain the relation-ship between long and short SSC actions and sprintperformance for different distances in well-trained fe-male athletes. These results, however, must be inter-preted with caution, because they only explain part ofa multifactorial relationship with sprinting perfor-mance. Coaches may, nevertheless, find it beneficial touse the CMJ, BDJ index, and 5B tests as part of a bat-tery of tests to help monitor and explain the charac-teristics associated with sprinting performance.

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Relationship of the Stretch-Shortening Cycle to Sprint Performance in Trained Female Athletes