Effect of an Exercise Protocol Focusing on Vastus Medialis Activation on the Cross-Sectional Area and Electrical Activity of the Vastus Medialis and Vastus Lateralis

In patients with lateral patellofemoral compression syndrome, the vastus medialis muscle is weaker than the vastus lateralis muscle. The purpose of the present study was to investigate the effect of an exercise protocol focusing on vastus medialis activation on the electrical activity and cross-sectional areas of the vastus medialis and vastus lateralis muscles.

In the current study, 30 females with lateral patellofemoral compression syndrome, aged 25.4±5.7, were selected and randomly divided into two groups. The experimental group participated in isokinetic knee extension exercises at terminal 30° extension arc with maximal external rotation of the leg for eight weeks. The control group did not participate in any regular exercise. Before and after the intervention, the cross sectional areas and electrical activities of the vastus medialis and vastus lateralis muscles were measured using ultrasonography and electromyography. Data were analyzed running independent and paired t-tests at the significance level of p < 0.05.

There were no significant differences in any of the variables between the two groups before intervention (p < 0.05). But after the intervention, the vastus medialis/vastus lateralis activity and cross-sectional area ratio in the experimental group were found to be significantly higher than those of the control group (p < 0.001).

According to the results, using isokinetic knee extension exercises can selectively strengthen the vastus medialis muscle and reduce the imbalance between vastus medialis and lateralis muscles in patients with lateral patellofemoral compression syndrome.