Purpose:​ Anterior cruciate ligament (ACL) injuries often occur in women during cutting maneuvers to evade a defensive player. Gender differences in knee kinematics have been observed, but it is not known to what extent these are linked to abnormal neuromuscular control elsewhere in the kinetic chain. Responses to defense players, which may be gender-dependent, have not been included in previous studies. This study determined the effects of gender and defense player on entire lower extremity biomechanics during sidestepping.

Methods:​ Eight male and eight female subjects performed sidestep cuts with and without a static defensive opponent while 3D motion and ground reaction force data were recorded. Peak values of eight selected motion and force variables were, as well as their between-trial variabilities, submitted to a two-way (defense × gender) ANOVA. A Bonferroni-corrected alpha level of 0.003 denoted statistical significance.

Results:​ Females had less hip and knee flexion, hip and knee internal rotation, and hip abduction. Females had higher knee valgus and foot pronation angles, and increased variability in knee valgus and internal rotation. Increased medial ground reaction forces and flexion and abduction in the hip and knee occurred with the defensive player for both genders.

Conclusions:​ A simulated defense player causes increased lower limb movements and forces, and should be a useful addition to laboratory protocols for sidestepping. Gender differences in the joint kinematics suggest that increased knee valgus may contribute to ACL injury risk in women, and that the hip and ankle may play an important role in controlling knee valgus during sidestepping. Consideration of the entire lower extremity contributes to an understanding of injury mechanisms and may lead to better training programs for injury prevention.