Vastus medialis activation during knee extension exercises: evidence for exercise prescription.

CONTEXT: Knee extension exercise is an important part of knee rehabilitation. Clinicians prescribe non-weight bearing exercise initially and progress patients to weight bearing exercise once they can perform a straight leg raise (SLR).
OBJECTIVE: Compare VM activation during a SLR and weight bearing exercises.
DESIGN: One-way repeated measures design.
SETTING: University Laboratory.
SUBJECTS: Fifteen healthy subjects. INTERVENTION: One SLR exercise and 6 weight-bearing knee extension exercises. MAIN OUTCOME MEASURES: Electromyographic amplitudes for the VM expressed as a percent maximum voluntary isometric contraction.
RESULTS: The SLR had greater activation than the single leg stance and bilateral squat exercises. The step-up and unilateral leg press exercises had the greatest activation.
CONCLUSIONS: SLR performance can be an important indicator for exercise progression. These results provide foundational knowledge to assist clinicians with exercise prescription.