An electromyographic analysis of the vastus medialis oblique and vastus lateralis during two selected knee extension exercises

The primary purpose of this study was to determine the ratio of activation between the VMO and the VL during an open chain knee exercise (dynamic knee extension) and a closed chain knee exercise (lateral step-up). A secondary purpose of this study was to compare muscle activation during the concentric and eccentric phase of the exercises. The data obtained during the knee extension exercise was further analyzed to compare the activity of the VMO and VL during three ranges of knee flexion: 0° - 30°, 30° - 60°, and 60° - 90°. Electromyographic (EMG) data was collected while 20 Ball State University students, who were asymptomatic for Patellofemoral Pain Syndrome, performed the two selected exercises. A one way ANOVA showed no statistically significant difference between the VMO: VL ratio of the two exercises, but the lateral step-up did produce a ratio greater than 1.0. A one-way ANOVA indicated a significant difference between the RMS values of the VL for the concentric and eccentric phase of the knee extension exercise. Based on the results of this study, the lateral stepup and eccentric training could be used to selectively strengthen the VMO for the treatment of PFPS.School of Physical EducationThesis (M.A.