Effect of Biofeedback Training of Hip Muscles on Pain, Muscle Strength and Their Electromyography in Patellofemoral Pain Syndrome

Objective Electromyography (EMG) biofeedback has been suggested as a relatively new approach to help resolve muscle disorders. This research aimed to evaluate the influence of 8 weeks of proximal pelvic muscle training and biofeedback on pain, muscle strength, and their EMG activity in individuals suffering from patellofemoral pain syndrome (PFPS). Materials & Methods This randomized clinical trial was performed on 30 young people aged 22 to 45 with PFPS. People in the intervention group (15 people) received EMG biofeedback of the abductor (gluteus medius) and external rotator (gluteus maximus) muscles along with routine physiotherapy treatments, including stretching exercises, isometric exercises of gluteal and quadriceps muscles, and conventional transcutaneous electrical nerve stimulation. In the control group (15 people), routine physiotherapy treatments were only performed on the patients. The participants of two groups were treated for 8 weeks, 3 sessions every week. Pain by a visual analog scale (VAS), maximal voluntary isometric strength (MVIC) of the abductor and external rotator muscles of the thigh with a dynamometer, and activity of these muscles, including maximum contraction, integrated EMG and onset EMG using EMG, were measured before and after the interventions. Results MVIC and EMG of the gluteus medius muscle demonstrated that the intervention group had more maximum EMG activity (P=0.043) and MVIC (P=0.003) than the control group. MVIC and the maximum EMG activity of the gluteus maximus muscle showed no significant difference between the two groups. Still, the increase in the integrated EMG of this muscle in the intervention group indicated a greater increase than in the control group (P=0.0001). Moreover, people in the intervention group had significantly less pain than the group of routine exercises alone after 8 weeks of treatment (P=0.016). Conclusion Adding 8 week biofeedback training of abductor and external rotator muscles to the routine therapeutic exercise in PFPS can lead to pain reduction, improvement of muscle strength and better performance of these muscles. This change could potentially slow down the degenerative process of the patellofemoral joint.