Effects of Selective Training on the Vastus Medialis Oblique in Patients with Patellofemoral Pain Syndrome

Objective: To evaluate the effects of electromyographic (EMG) biofeedback training and patellar taping targeted interventions for the vastus medialis oblique (VMO) on pain, function, muscle strength, the VMO-to-vastus lateralis (VL) EMG activity ratio, and onset timing differences in patients with patellofemoral pain syndrome (PFPS).Design: Randomized controlled trial.Methods: Thirty-seven female patients with PFPS were randomly assigned to one of three groups: EMG biofeedback (n=13), patellar taping (n=12), and control (n=12).All participants engaged in conventional quadriceps strengthening exercises for six weeks.Additionally, the two intervention groups received selective VMO training through either EMG biofeedback or patellar taping.Outcome measures included the visual analog scale, anterior knee pain scale (AKPS), lower extremity functional scale, maximal voluntary contraction, VMO/VL EMG activity ratio, and VMO VL onset timing difference during stair ascent and descent.Assessments occurred before and after the intervention.Results: All groups displayed significant within-group improvements in pain, function, and muscle strength (p<0.05).Post-intervention, the patellar taping group exhibitedsignificantly higher AKPS scores compared to the control group.During stair ascent, the VMO/VL activity ratio significantly increased in both the EMG biofeedback and patellar taping groups.No significant between-group differences were found observed onset timing, although reductions in onset delay were noted across all groups.Conclusions: Selective VMO training using either EMG biofeedback or patellar taping enhanced the VMO/VL activation ratio during stair ascent.When combined with conventional strengthening exercises, these strategies effectively rectify muscular imbalances and improve function in individuals with PFPS.