Contraction mode and velocity affect bilateral torque asymmetry direction but not magnitude in female basketball athletes and controls

The purpose of this study was to investigate bilateral asymmetries in isokinetic strength of lower limb muscles under different contraction modes and velocities in elite and sub-elite basketball athletes, and control participants. Twenty-two female basketball players (12 elite, 10 sub-elite) and 19 physically active females performed concentric and eccentric knee extensions (KE), knee flexions (KF), plantar flexions (PF), and dorsiflexions at different angular velocities (knee joint: 60°·s ⁻¹ , 180°·s ⁻¹ and ankle joint: 30°·s ⁻¹ , 90°·s ⁻¹ ). Bilateral asymmetry magnitude and direction (left or right limb) in torque were calculated. Kappa coefficients analysis showed that asymmetry direction was inconsistent across different contraction modes and angular velocities for KE (range: −0.32 to 0.47), KF (range: −0.12 to 0.58), and PF (range: −0.23 to 0.78) for both female basketball athletes and control participants, while DF (range: 0.66 to 1.00) presented consistent asymmetry direction. Linear mixed-effects models indicated that asymmetry magnitude of KE, KF, and PF did not differ ( p  > 0.05) across isokinetic testing conditions for both athletes and controls. These findings suggest that direction of bilateral asymmetries but not magnitude differs between contraction modes, angular velocities, and muscle group. Training status did not affect bilateral asymmetry in females. Single-mode or single-velocity testing may misrepresent bilateral asymmetry, therefore assessment should include multiple modes and velocities to guide individualized training.