INTRODUCTION: The patellofemoral pain syndrome (PFPS) it is a common problem affecting one in each four people. Alteration in the onset time and intensity of contraction of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles are considered important factors in the aetiology of PFPS. However, few studies exist about the function of the oblique portion of the vastus lateralis (VLO) and none on the onset time of VLO in functional activities in normal subjects and with PFPS. OBJECTIVE: The purpose of this study was to investigate the onset time in the VMO, VLO and VL longus (VLL) muscles during the gait. MATERIALS AND METHODS: Sample was formed by 15 subjects without and 12 with PFPS. Electromyographic data were obtained of the VMO, VLO and VL muscles during treadmill walking with and without inclination. The relative difference in the onset time (DRO) among VMO-VLL and VMO-VLO were determined from the average of 3 strides. Results: There was difference among the subject with and without PFPS in relation to DRO among VMO-VLL. In the subject with PFPS the order at the beginning of the electric activity it was VLL following for VLO and after VMO. In the individuals without the pathology the order was different, first VMO, after VLO and last VLL. CONCLUSION: The findings suggest that the activation of VMO after the one of VLL could aid in the development and maintenance of PFPS, while the time of activation of VLO possesses smaller participation.
Gait; Patellofemoral joint; VLO muscle
