The Effect of Electrical Muscle Stimulation and Strength Training on Mechanics during Single-Leg Squat in Patients with Patellofemoral Pain Syndrome
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Graphical Abstract
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Abstract
Objective: Patellofemoral pain syndrome(PFPS) is a common causative factor of knee pain. The aim of this study was to investigate the lower limb mechanics and muscle activation during single-leg squats following 6-week training interventions of exercise and electrical muscle stimulation(EMS). Methods: Forty-six participants were recruited and randomly assigned into the muscle strength training(MST) group and EMS(combining EMS with strength training) group. Lower limb mechanics and muscle activation during single-leg squats were collected at before and after the 6-week intervention for each group by using infrared motion capture systems, force platform, and surface electromyography. Additionally, the visual analog score(VAS) and anterior knee pain scale(AKPS) were also recorded. Two-way(group by time) analysis of variance with repeated measures were applied to analyze the data. Results: After 6-week intervention, the VAS score, maximum hip internal rotation angle, maximum hip abduction moment,maximum knee abduction angle, peak knee three-dimensional moment, and peak patellofemoral joint reaction force during singleleg squat were all decreased; meanwhile, the maximum hip flexion angle, maximum hip external rotation moment, and muscle activation in gluteal and vastus medialis oblique were increased. Compared with the MST group, the EMS group demonstrated greater changes in increasing AKPS score and decreasing the maximum hip adduction angle, maximum knee flexion angle,maximum knee external rotation angle, and peak patellofemoral joint stress compared to the MST group following training.Conclusion: EMS training is beneficial for improving knee function and relieving pain in patients with PFPS compared to MST.EMS training is also contributed to altering hip and knee movement patterns during single-leg squats, consequently reducing the load on the patellofemoral joint.
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