Electromyographic activity of the lower limb in runners with anterior knee pain while running

Introduction: Anterior knee pain (AKP) is a common musculoskeletal condition that affects runner athletes of different ages. Lower level and delayed onset electromyographic activity (EMG) of the vastus medialis oblique muscle (VMO) and the vastus lateralis (VL) have been identified in patients with AKP. Recently, it has also been suggested that a delay or decrease in the level of gluteus medius (GM) activation may influence the biomechanics of patellofemoral joint. Thus, this study aimed to compare the EMG patterns of VMO, VL, and GM during treadmill running in recreational runners with AKP. Methods: Twelve men with AKP (PG) evaluated by the scale (Scoring of Patellofemoral Disorders) and 20 healthy subjects (CG) participated in this study. The EMG of the muscles was collected during 15 s of running at a speed of 11 km/h. The running cycle was captured by four infrared cameras and 3D visual analysis software. The activation level was measured by the rectified EMG integral and the onset of contraction by the Teager-Kaiser energy operator. Results: The VMO and GM muscles showed significantly shorter pre-activation times and contraction times in the group of runners with pain (p < 0.05). Before the start of the running cycle, only the VMO muscle showed differences, with a lower level for the AKP group. In the other phases of the cycle, there were no significant differences. Conclusion: The results suggest that both the VMO and GM have delay and activation deficits, without changes in the level of activation in patients with AKP, which can contribute to patellar misalignment and consequently to the appearance of pain. © 2021, Sociedade Brasileira de Engenharia Biomedica.