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 = 0.006). VMO activity predicted 47.1% of peak knee flexion angle variance (R2 = 0.471, P = 0.000). VMO and VL activity predicted 49.5% of knee flexion displacement variance (R2 = 0.495, P = 0.000). Conclusions. Increased quadriceps and GMAX activation, with a lack of hamstring and gastrocnemius activation, showed a relationship with decreased knee flexion angle and we speculate this movement pattern to be a potential risk-factor for ACL injury.The electrodes for the gastrocnemius were placed over the bulge of the lateral head of the gastrocnemius (Basmajian, Blumenstein, and Dismatsek, 1980). Electrode placement was confirmed with manual muscle testing. Subjects were thenanbsp;...
|Title||:||The Relationship Between Lower Extremity Muscle Activity and Knee Flexion Angle During a Jump-landing Task|
|Author||:||Meghan C. Walsh|
|Publisher||:||ProQuest - 2008|