Vastus Medialis Oblique/Vastus Lateralis Muscle Activity Ratios for Selected Exercises in Persons With and Without Patellofemoral Pain Syndrome

BACKGROUND AND PURPOSE: The purpose of this study was to determine which of selected exercises with and without the feet free to move would enhance vastus medialis oblique muscle (VMO) activity over that of the vastus lateralis muscle (VL) and whether the use of taping would increase VMO activity. SUBJECTS: Twenty-one subjects without patellofemoral pain (PFP) syndrome and 10 subjects with PFP syndrome, aged 19 to 43 years (X = 26, SD = 7), participated. METHODS: Subjects were studied for the normalized, integrated electromyographic (IEMG) activity of their VMO, VL, and adductor magnus muscle (subjects without PFP syndrome) and the VMO/VL ratio using wire electrodes. RESULTS: One exercise demonstrated greater activation of the VMO over the VL when compared with similar exercises in subjects without PFP syndrome. The mean VMO/VL activity ratio for terminal knee extension was 1.2 (SD = 0.5) with the hip medially rotated and 1.0 (SD = 0.4) with the hip laterally rotated. Although subjects reported that patellar taping decreased pain 94% during the step-down exercise, the VMO/VL ratio was not changed. CONCLUSION AND DISCUSSION: The results suggest that neither exercises purported to selectively activate VMO activity nor patellar taping improve the VMO/VL ratio over similar exercises.