EMG Analysis of Vastus Medialis Obliquus/Vastus Lateralis Activities in Subjects with Patellofemoral Pain Syndrome before and after a Home Exercise Program

Abstract

The objective of this study was to analyze the effects of an 8-week home exercise program with and without electromyographic biofeedback on the relative activations of the vastus medialis obliquus and vastus lateralis using electromyographic measurement in patients with patellofemoral pain syndrome. Twenty-six subjects were randomly allocated into "exercise only" (Group 1) and "electromyographic biofeedback + exercise" (Group 2) groups. Both groups performed the same exercise program and Group 2 received electromyographic biofeedback from a system that provided real-time information on the relative activations of the vastus medialis obliquus and vastus lateralis during the exercises. The intensity of the knee pain was also recorded on a pain severity scale, respectively. These parameters were measured before and after the 8-week home exercise program. The results show that Group 1 had insignificant changes in the vastus medialis obliquus/vastus lateralis electromyographic ratio (p=0.355), whereas Group 2 had significantly a higher vastus medialis obliquus/vastus lateralis electromyographic ratio (p=0.017) when performing normal activities throughout a 6-hour assessment period. The present results reveal that the incorporation of electromyographic biofeedback into a home exercise program could facilitate the activation of the vastus medialis obliquus muscle, such that the muscle could be preferentially recruited during daily activities.