Sex differences in eccentric hip-abductor strength and knee-joint kinematics when landing from a jump

Context: Decelerating movements such as landing from a jump have been proposed to be a common mechanism of injury to the anterior cruciate ligament (ACL). Objective: To compare eccentric hip-abductor strength and kinematics of landing between men and women when performing a hopping task. Setting: Research laboratory. Patients: 18 healthy subjects (10 women, 8 men). Main Outcome Measures: Eccentric peak torque of the hip abductors and peak knee-joint angles during a 350-millisecond interval after impact. Results: No significant sex differences were present, but there was a significant inverse relationship between women's eccentric peak torque and peak knee-valgus angle (r = -.61, P = .03). Conclusions: Women with larger eccentric peak torque demonstrated lower peak knee-valgus angles. By not reaching as large of a valgus angle, there is potentially less stress on the ACL. Increasing eccentric hip-abductor strength might improve knee-joint kinematics during landing from a jump.