Muscle Activation of Vastus Medialis Oblique and Vastus Lateralis in Sling-Based Exercises in Patients with Patellofemoral Pain Syndrome: A Cross-Over Study.

Wen-Dien Chang,Ping-Tung Lai,Wei-Syuan Huang

doi:10.1155/2015/740315

Abstract

Objectives. To examine what changes are caused in the activity of the vastus medialis oblique (VMO) and vastus lateralis (VL) at the time of sling-based exercises in patients with patellofemoral pain syndrome (PFPS) and compare the muscular activations in patients with PFPS among the sling-based exercises. Methods. This was a cross-over study. Sling-based open and closed kinetic knee extension and hip adduction exercises were designed for PFPS, and electromyography was applied to record maximal voluntary contraction during the exercises. The VMO and VL activations and VMO : VL ratios for the three exercises were analyzed and compared. Results. Thirty male (age = 21.19 ± 0.68 y) and 30 female (age = 21.12 ± 0.74 y) patients with PFPS were recruited. VMO activations during the sling-based open and closed kinetic knee extension exercises were significantly higher (P = 0.04 and P = 0.001) than those during hip adduction exercises and VMO : VL ratio for the sling-based closed kinetic knee extension and hip adduction exercises approximated to 1. Conclusions. The sling-based closed kinetic knee extension exercise produced the highest VMO activation. It also had an appropriate VMO : VL ratio similar to sling-based hip adduction exercise and had beneficial effects on PFPS.

Highlights

Patellofemoral pain syndrome (PFPS) is a musculoskeletal disorder that often occurs in the lower extremities of athletes and has a high prevalence in women aged 18–35 years [1]
During a knee extension exercise, the patella is pulled by the quadriceps muscle and the cranial slides within the femoral trochlear groove, and the exercise is an efficacious treatment for an imbalance of vastus medialis oblique (VMO) and vastus lateralis (VL) muscles, which is thought to be present in patients with PFPS, to stabilize patellar tracking [2]
The repeatedmeasures analysis of variance showed that the type of the sling-based exercise had significant relation with the maximal voluntary contraction (MVC) of the VMO and VL and VMO : VL ratio (P < 0.05)

Summary

Introduction

Patellofemoral pain syndrome (PFPS) is a musculoskeletal disorder that often occurs in the lower extremities of athletes and has a high prevalence in women aged 18–35 years [1]. Empirical evidences represented that an imbalance of VMO and VL muscle activities leads to excessive lateral tracking of the patella and rubbing of the lateral femoral condyle, which causes articular surface erosion and degeneration and induces pain [2]. During a knee extension exercise, the patella is pulled by the quadriceps muscle and the cranial slides within the femoral trochlear groove, and the exercise is an efficacious treatment for an imbalance of VMO and VL muscles, which is thought to be present in patients with PFPS, to stabilize patellar tracking [2]. Previous study has indicated that the value of VMO : VL ratio in patients with PFPS was 0.54 : 1 [5]; this is possibly because imbalance of VMO and VL muscle activities causes insufficient medial patellar

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