Associations of Hip Abductor-to-Adductor Strength and EMG Activation Ratios with Lower-Limb Biomechanics During Single-Leg Landing

Background/Objectives: Hip abductor-to-adductor (ABD:ADD) strength characteristics and muscle activation may contribute to lower-limb control during landing, but their respective associations with landing biomechanics remain unclear. This study examined associations of the ABD:ADD strength ratio, strength imbalance index, and EMG activation ratios with lower-limb biomechanics during forward and lateral single-leg landing. Methods: Twenty male Division I collegiate basketball and volleyball athletes completed isokinetic hip strength testing, maximal voluntary isometric contraction EMG testing, and forward (FWD) and lateral (LAT) single-leg landing tasks. EMG activation ratios were quantified at initial contact (IC), peak ground reaction force (GRF), and from IC to peak GRF. Correlation analyses and exploratory regressions were performed. Results: During FWD Landing, strength measures were associated with knee flexion, knee transverse-plane angle, and hip frontal-plane moment, while the EMG ratio at IC was associated with hip and knee frontal-plane angles and hip transverse-plane moment. During LAT Landing, strength measures were associated with hip and knee kinematics and hip and knee frontal-plane moments. Mean early-phase EMG ratio was associated with hip flexion, knee flexion, hip frontal-plane angle, and hip frontal-plane moment. Retained regression models explained 20–33% of outcome variance. Conclusions: Hip ABD:ADD strength characteristics and EMG activation ratios were associated with different aspects of single-leg landing biomechanics. During lateral landing, the mean early-phase EMG ratio was associated with hip and knee flexion angles and hip frontal-plane angle at peak GRF. These exploratory findings indicate that strength capacity and task-specific neuromuscular recruitment provide complementary information regarding hip muscle function during landing.