Effects of Ankle Dorsiflexion on Vastus Medialis Oblique and Vastus Lateralis Muscle Activity During Straight Leg Raise Exercise with Hip External Rotation in Patellofemoral Pain Syndrome

Abstract

Abstract Objectives: The purpose of this study was to investigate the effect of combined ankle dorsiflexion [DF] and straight leg raise with hip external rotation [SLRER] on the vastus medialis oblique [VMO] and vastus lateralis [VL] muscle activity and VMO/VL ratio in subjects with patellofemoral pain syndrome [PFPS] and healthy normal control [HNC] subjects. Methods: Twenty-six subjects [13 in the PFPS group and 13 in the HNC group] were recruited and all subjects performed two exercises; SLRER and SLRER with DF [SLRERDF]. Surface electromyography was used to collect data of the VMO and VL muscle activity. A two-way mixed analysis of variance was used to determine the statistical significance of VMO and VL muscle activity and VMO/VL ratio. Results: The VMO muscle activity during SLRERDF was significantly greater than SLRER in both groups and the VL muscle activity during SLRERDF was significantly greater than SLRER in both groups. For the VMO/VL ratio, there were no significant main effect of group and exercise. Conclusions: Although the findings of this study did not demonstrate that SLRERDF is effective for targeting the VMO over VL muscle activity in the PFPS group, SLRERDF could be recommended as activation strategy for subjects with the general quadriceps weakness.