Preferential strengthening of VMO muscle during selected biomechanical rehabilitative exercises of automotive workers with patellofemoral pain syndrome.

BACKGROUND: Automotive workers are engaged in occupational activities like engine tune-ups, oil changes, tire rotation, wheel balancing, replacing filters etc. These activities involve prolonged sitting, awkward postures, squatting and kneeling, which are known risk factors to cause patellofemoral pain syndrome (PFPS).

OBJECTIVE: This paper aims to investigate the effects of selected biomechanical rehabilitative exercises (BRE) on integrated electromyography (iEMG) activity of vastus medialis oblique (VMO) and vastus lateralis (VL) muscles so as to identify suitable ones to alleviate PFPS of automotive workers.

METHODS: Eleven subjects, automotive workers having PFPS, performed four BRE: (1) short arc quad with neutral hip position (SAQN), (2) short arc quad with externally rotated hip position (SAQER), (3) medial tibial rotation (MTR), and (4) hip adduction (HA).

RESULTS: Mean iEMG activity of VMO muscle is more than that of VL muscle during all BRE. However, one way ANOVA with repeated measures indicates that mean iEMG activity of VMO muscle is significantly higher than that of VL muscle during SAQER only. VMO/VL ratio is not significantly different across the four BRE.

CONCLUSIONS: Results suggest a range of options for choosing appropriate BRE for treating automotive workers with PFPS. However, SAQER may directly be recommended for preferential strengthening of VMO muscle.