Vastus lateralis and vastus medialis obliquus activity during a straight-leg raise and knee extension with lateral hip rotation

Objective: To compare average electromyogram (EMG) activity of the vastus medialis obliquus (VMO) and vastus lateralis (VL) during straight-leg raise (SLR) and knee extension (KE) with the hip in neutral and lateral rotation. Design: 1 X 4 factorial repeated-measures. Setting. Laboratory. Participants: 13 male college students. Intervention: SLR with hip flexed at 400, in neutral position, and maximally laterally rotated and KE with hip in neutral and maximally laterally rotated. Main Outcome Measure: Average EMG activity during each of the 4 conditions, normalized against peak muscle activity during that trial. Results: No differences were observed between exercises in VMO activity (F-3,F-36 = 0.646, P > .05), VL activity (F-3,F-36 = 1.08, P > .05), or VMO:VL ratio (F-3,F-36 = 0.598, P > .05). Conclusions: Electrical activity of the VMO or VL and VMO:VL ratio do not change with hip position or exercise.