Abstract
In this study, we investigated the association of magnitude and agreement in direction between asymmetries measured on single-joint (hip and trunk), complex movement (jumping), and skill (change of direction (CoD)) levels. The study sample comprised 43 junior- and senior-level (age = 20.5 ± 6.0 years; height = 194.5 ± 7.2 cm; body mass = 86.8 ± 10.1 kg) elite male basketball players. Both limbs/sides were tested in hip and trunk isometric strength; passive range of motion (RoM); unilateral, horizontal, and vertical jumping; and CoD tests, from which asymmetry indexes were calculated. The associations between asymmetry magnitudes were calculated with Spearman’s ρ correlation coefficient. The agreement between the direction of asymmetries on different levels was calculated with Cohen’’s Kappa (κ) coefficient. The average magnitude of asymmetry varied substantially (2.9–40.3%). Most associations between asymmetry magnitudes measured on different levels were small and statistically non-significant, with a few exceptions of moderate and large associations. Asymmetry in single-leg countermovement jump parameters was strongly associated with hip abduction maximal strength (ρ = 0.58 and 0.50, p < 0.01). Agreement between asymmetry directions was slight to fair, with a few moderate exceptions. Results indicate that multiple tests are needed to obtain a comprehensive picture of athletes’ asymmetries and that universal thresholds and golden standard tests for return to play should be reconsidered and reinvestigated.
Highlights
Asymmetry, which refers to comparing the ability of one limb/side to another, has been a popular topic in recent sport science research [1]
A study of Bishop et al [23], conducted on female soccer players, observed a substantial agreement between direction of asymmetry measured with the single-leg squat and countermovement jump (Kappa = 0.35–0.61), but slight to fair agreement when the same jumps were compared with single-leg drop jumps (Kappa = −0.26–0.26). These results indicate that asymmetry direction is mostly task-dependent, with few exceptions, when asymmetry is measured with various jumping tests
From a rehabilitation and return to play perspective, testing asymmetry with horizontal jumps has previously been widely practiced [35]. This and previous studies show that the horizontal jumping test shows similar sensitivity to the CoD test when it comes to asymmetry [24]
Summary
Asymmetry, which refers to comparing the ability of one limb/side to another, has been a popular topic in recent sport science research [1]. It has been investigated for the purpose of finding its connection to sports injuries [2] or performance [3]. Just as with motor abilities, lateral asymmetry can be inspected on different levels: single-joint level, such as in knee flexion/extension [4]; complex movement level, such as in jumping [7]; and skill level, such as in CoD [10]. Past research has been mostly concentrated on the asymmetry magnitude [14], while the direction of asymmetry has only recently been in focus [15]
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