The relationship between lower extremity muscle activity and knee flexion angle during a jump-landing task

Objective: To determine relationships between lower extremity muscle activity and knee flexion angle during a jump-landing task. Subjects: Thirty recreationally active people free from previous ACL injury. Methods: Muscle activity of the lower extremity and knee flexion angle were recorded during 10 trials of the jump-landing task. Data was analyzed using correlation and multiple regression statistical analyses. Results: Eight significant negative relationships were found, VMO, GMAX activity and Q:H ratio with knee flexion angle at initial contact (VMO: r = -0.382, P = 0.045, GMAX: r = -0.385, P = 0.043, Q:H ratio: r = -.442, P = .018). VMO, VL, and GMAX activity with peak knee flexion angle (VMO: r = -0.687, P =0.00, VL: r = -0.467, P = .011, GMAX: r = -0.386, P = 0.043). VMO and VL activity with knee flexion displacement (VMO: r = -0.631, P= 0.00, VL: r = -0.453, P = 0.014). Q:H ratio and GMAX activity predicted 34.7% of knee flexion angle variance at initial contact (R2= 0.347, P