Backgrounds and Aim: An increased cross-sectional area of the distal portion of the vastus medialis muscle without any increase in the cross-sectional area of the vastus lateralis is associated with an increased risk of patella cartilage injuries, and an increase in patella bone volume. The aim of the present study was to evaluate the effects of 8 weeks of specific vastus medialis training on cross sectional areas of vastus medialis and vastus lateralis in women with patellofemoral pain.

Material and Methods: 24 women with patellofemoral pain participated in this experimental study. Subjects were randomly divided into training (age: 24.1±2.6 years) and control (age: 24.0±2.1 years) groups. Each training program consisted of three sessions per week for 8 weeks. Supervision of the workouts was maintained at all times. Targeted training included the leg press exercise to the last 45º of knee extension/flexion with vigorous hip adduction in the training group. The cross-sectional areas of the distal vastus medialis and lateralis were measured 37.5 mm above the insertion site of quadriceps tendon at the proximal pole of the patella by using ultrasonography before and after exercise in both groups. Paired t- test and independent t-test were used for statistical analysis (p<0.05).

Results: The cross-sectional areas of both distal vastus medialis (P=0.03) and lateralis (P=0.01) increased after training significantly in the training group, while vastus medialis showed more increase in cross-sectional area in comparison to vastus lateralis but this differences was not statistically significant (P=0.128). In addition, the control group did not show any significant difference (P>0.05).

Conclusion: Cross-sectional area of distal vastus medialis increased more than that of vastus lateralis which showed no significant difference. This training method could be helpful in women with patellofemoral pain syndrome.

Keywords: Patellofemoral pain syndrome, Cross sectional area, Vastus medialis muscle, Vastus lateralis muscle.