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Michelle Boling, Darin Padua, J. Troy Blackburn, Meredith Petschauer and Christopher Hirth

Context:

Clinicians commonly attempt to facilitate vastus medialis oblique (VMO) activity by instructing patients to squeeze a ball between their knees during squatting exercises.

Objective:

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.

Design:

Single test session.

Participants:

Fifteen healthy subjects, with no history of knee pain, volunteered for this study.

Intervention:

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.

Results:

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.

Conclusions:

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.

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Christopher J. Hirth

Column-editor : Darin A. Padua

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Johna K. Register, Jason P. Mihalik, Christopher J. Hirth and Thomas E. Brickner

Column-editor : Joseph J. Piccininni