Abstract
Despite growing research in the field of inter-limb asymmetries (ILAs), little is known about the variation of ILAs in different populations of athletes. The purpose of this study was to compare ILAs among young basketball, soccer and tennis players. ILAs were assessed in three different types of tests (strength, jumping and change of direction (CoD) speed), each including different tasks: (1) bilateral and unilateral counter movement jump, (2) isometric strength of knee extensors (KE) and knee flexors (KF), and (3) 90° and 180° CoD. Generally, the absolute metrics showed strong reliability and revealed significant differences (p < 0.05) among the three groups in KE maximal torque, KE and KF rate of force development and in both CoD tests. For jumping ILAs, power and force impulse metrics exhibited significant between-limb differences between groups, compared to jump height. For strength and CoD speed ILAs, only KF maximal torque and 180° CoD exhibited significant differences between groups. Greater KF strength ILAs in soccer players and counter-movement jump ILAs in tennis players are most probably the result of sport-specific movement patterns and training routines. Sport practitioners should be aware of the differences in ILAs among sports and address training programs accordingly.
Highlights
Inter-limb asymmetry (ILA), which refers to the difference in performance or function of one limb relative to the other [1], has been a popular topic in recent years
Even though it was previously shown that total time in change of direction (CoD) test is not sensitive metric for detecting ILAs [17,28] our results suggest that CoD at a greater angle (180◦ ) may be more discriminative compared to CoD at 90◦
Our results revealed that jump H and FI had better discriminant validity compared to P, as soccer players had higher non-preferred jump H (CMJUL ) compared to basketball and tennis players, as well as higher FI on preferred leg compared to tennis players (CMJBL ) and basketball players (CMJUL )
Summary
Inter-limb asymmetry (ILA), which refers to the difference in performance or function of one limb relative to the other [1], has been a popular topic in recent years. Numerous methods of assessment have been used to quantify ILA, ranging from the back squat [2] and isokinetic dynamometry [3]. For jumping, and the “505” test [8] for change of direction (CoD) speed. These methods have been a common choice for assessing ILA in athlete populations, owing to the importance of strength [9], power [10] and CoD speed [11] performance in sport. The selection of multiple tests seems advisable when quantifying ILA to provide a meaningful picture of any existing differences. During back squat, greater ILAs in vertical ground reaction force were seen in the subjects who started the lift with uneven weight distribution (4.4–4.9%), compared to those who had symmetrical weight distribution (2.1–2.5%) [2]
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