EMG ANALYSIS OF TWO PORTIONS OF THE VASTUS MEDIALIS MUSCLE DURING SELECTED KNEE REHABILITATION EXERCISES

Abstract

Despite a prevalence of literature describing the function and rehabilitation of the vastus medialis oblique (VMO) muscle, no literature exists which substantiates the existence of the VMO as a separate muscle entity from the vastus medialis longus (VML) muscle. The purpose of this study was to determine if the VMO and VML muscles exhibit any differences in muscle activity during performance of commonly performed knee rehabilitation exercises. Electromyographic (EMG) action potential amplitude from both the VMO and VML of normal adults were obtained simultaneously via indwelling electrodes during performance of ten different knee rehabilitation exercises. A two-way repeated measures analysis of variance was performed with the two portions of the vastus medialis (VM) muscle as one independent variable, the knee exercises as the second independent variable, and percent maximal voluntary contraction (%MVC) data as the dependent variable. Data was analyzed to determine whether any differences existed between the VMO and VML during performance of any of the selected exercises. Analysis of the data revealed that although significant differences existed in %MVC's generated between exercises, no differences were seen between the VMO and VML during any of the individual exercises or the group of exercises as a whole. Exercises utilized to strengthen one portion of the VM muscle will simultaneously strengthen the other portion. These findings show that no functional differences exist between the VMO and VML, and lessen the credibility of the theory that they are separate muscle entities.