Vastus Medialis Activation during Knee Extension Exercises: Evidence for Exercise Prescription

in Journal of Sport Rehabilitation
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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).


Compare VM activation during a SLR and weight bearing exercises.


One-way repeated measures design.


University Laboratory.


Fifteen healthy subjects.


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.


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.


SLR performance can be an important indicator for exercise progression. These results provide foundational knowledge to assist clinicians with exercise prescription.

Lori Bolgla is with the Medical College of Georgia, Department of Physical Therapy, Augusta, GA. E-mail:; Scott Shaffer is with Physical Therapy at U.S. Army-Baylor University, Fort Sam Houston, TX. Terry Malone is with the University of Kentucky, Rehabilitation Sciences, Lexington, KY.