Sex differences in lower landing kinematics through neuromuscular fatigue

Athletes in volleyball, basketball, and soccer have rapid deceleration of the lower extremity, such as landing from a jump [1, 2]. The anterior cruciate ligament injury has been reported to happen to women about three times more often than men in soccer and basketball [3]. Recently, Ford et al [1, 4] and Kernozek et al [1, 5] reported that women demonstrated significantly increased frontal-plane motion of the knee when landing compared with men. Subjects with poor hip abductor strength may demonstrate decreased proximal control of the hip, which then may result in inferior knee kinematics [1, 6]. High levels of strength and muscle strength balance between antagonistic muscle groups may be used to protect the knee during jumping and landing activities [7]. It is known that under loading conditions women are more fatigue-resistant than men, due to slow muscle fibre and relative larger muscle cross-sectional area in females slow muscle fibre [8]. Female hormones reduce mechanic sensitivity of bone tissue and its osteogenic response during mechanic landing [9]. Furthermore, females squat less than males during jump [10]. Jumping as a natural stretch-shortening cycle (SSC) muscle action, which is known to enhance muscle output in the final shortening phase (push-off), is compared with the pure shortening action alone [11]. The relationship between fatigue and antagonistic muscle group strength during prolonged activities suggests that it may play a vital role in neuromuscular control of the knee. Also anterior cruciate ligament injuries have happened more often in females than males from a jump through fatigue that suggests playing attention to that problem. Thus, the aim of the study was to evaluate sex differences in landing from a jump in relation to lower extremity landing kinematics through neuromuscular fatigue.