Six methods for classifying lower-limb dominance are not associated with asymmetries during a change of direction task.

Abstract

Quantifying asymmetries between dominant and non-dominant limbs is a common research objective aimed at identifying systematic differences between limbs and establishing normative ranges of asymmetry. Multiple methods for classifying limb dominance exist, and it is unclear how different methods relate to directional asymmetries during change of direction (CoD). This study aimed to determine whether different methods of classifying limb dominance, including a novel CoD task-specific method, identified significant inter-limb asymmetries during a 90° CoD task. Fifty participants completed a testing battery consisting of jumping, hopping, CoD, and isokinetic dynamometry. Limb dominance was classified for each participant according to preferred kicking limb, vertical jump height, horizontal hop distance, initial force plate contact during landing, max isokinetic knee extensor strength, and turning velocity. Asymmetries in whole-body and joint-level mechanics were defined using each method. No method for classifying limb dominance was associated with consistent inter-limb biomechanical asymmetries during CoD, and no method was related to any other method. The magnitude of asymmetry relative to the magnitude of absolute asymmetry present within the cohort suggests that using these tasks to classify the dominant limb in this CoD is akin to assigning dominance to a randomly selected limb. Previous observations of group symmetry during CoD may be statistical artifacts as opposed to a true indication of normative movement. Until an appropriate means of classifying limbs during CoD is established, quantifying normative asymmetry based on limb dominance should be done with caution.