Drop Jump Asymmetry is Associated with Reduced Sprint and Change-of-Direction Speed Performance in Adult Female Soccer Players.

Chris Bishop,Sean Maloney,Paul Read,Jason Lake,Tom Bromley,Irineu Loturco,Anthony Turner

doi:10.3390/sports7010029

Abstract

Studies that examine the effects of inter-limb asymmetry on measures of physical performance are scarce, especially in adult female populations. The aim of the present study was to establish the relationship between inter-limb asymmetry and speed and change-of-direction speed (CODS) in adult female soccer players. Sixteen adult players performed a preseason test battery consisting of unilateral countermovement jump (CMJ), unilateral drop jump (DJ), 10 m, 30 m, and 505 CODS tests. Inter-limb asymmetry was calculated using a standard percentage difference equation for jump and CODS tests, and Pearson’s r correlations were used to establish a relationship between asymmetry and physical performance as well as asymmetry scores themselves across tests. Jump-height asymmetry from the CMJ (8.65%) and DJ (9.16%) tests were significantly greater (p < 0.05) than asymmetry during the 505 test (2.39%). CMJ-height asymmetry showed no association with speed or CODS. However, DJ asymmetries were significantly associated with slower 10 m (r = 0.52; p < 0.05), 30 m (r = 0.58; p < 0.05), and 505 (r = 0.52–0.66; p < 0.05) performance. No significant relationships were present between asymmetry scores across tests. These findings suggest that the DJ is a useful test for detecting existent between-limb asymmetry that might in turn be detrimental to speed and CODS performance. Furthermore, the lack of relationships present between different asymmetry scores indicates the individual nature of asymmetry and precludes the use of a single test for the assessment of inter-limb differences.

Highlights

Inter-limb asymmetry has been a common line of investigation in recent years, with numerous studies reporting the prevalence of side-to-side differences during various tests of physical capacity [1,2,3]
All tests reported good to excellent reliability (ICC = 0.80–0.94) and acceptable variability (CV ≤ 7.51%)
Pearson’s r correlations between inter-limb asymmetry scores and fitness tests are shown in Individual asymmetry values for each player are presented in Figure 1 for jump height (CMJ), jump height and reactive strength index (RSI) (DJ), and total time (505)

Summary

Introduction

Inter-limb asymmetry has been a common line of investigation in recent years, with numerous studies reporting the prevalence of side-to-side differences during various tests of physical capacity [1,2,3]. Sports 2019, 7, 29 when choosing the appropriate test for athletes, such as test reliability, needs of the athlete and availability of equipment [4] Whilst these factors must be given careful consideration when measuring asymmetry, it is difficult to argue against the importance of strength and power in almost all athletes. Strength asymmetry (typically peak force or torque) have been shown to be negatively correlated with jump performance [9], speed and change-of-direction speed (CODS) [8], and kicking accuracy [11]. Whilst useful, such test methods often require substantial time commitments and expensive equipment, making them harder to conduct for practitioners in the field. Alternative methods of assessing inter-limb asymmetry may be required

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Methods

Results

Discussion

Conclusion