Clinicians commonly attempt to facilitate vastus medialis oblique (VMO) activity by instructing patients to squeeze a ball between their knees during squatting exercises.
To determine whether VMO activation amplitude and the VMO to vastus lateralis (VL) activation ratio (VMO:VL) were altered when performing active hip adduction during a dynamic squat exercise.
Single test session.
Fifteen healthy subjects, with no history of knee pain, volunteered for this study.
Surface EMG of the VMO, VL, and hip adductor (ADD) muscles were recorded while subjects performed 10 consecutive squats against their body weight through a range of 0° to 90° of knee flexion. Subjects performed the squat exercises during two different conditions: (1) active hip adduction and (2) no hip adduction.
Main Outcome Measures:
Average VMO EMG amplitude and VMO:VL ratio were determined during the knee flexion (0° to 90°) and knee extension (90° to 0°) phases of the squat exercise.
Active hip adduction did not significantly change VMO amplitude or VMO:VL ratio during the knee flexion or knee extension phases of the dynamic squat exercise.
Based on these results, we conclude that VMO amplitude and the VMO: VL ratio are not influenced by performing active hip adduction during a dynamic squat exercise in healthy subjects.
The authors are with the Department of Exercise and Sport Science at the University of North Carolina at Chapel Hill.