Electromyographic analysis of the gluteus medius in five weight-bearing exercises.

Weight-bearing exercises are frequently used to train and strengthen muscles of the hip. These exercises have been advocated in the rehabilitation of a variety of hip and knee dysfunctions. Limited evidence is available to describe the level of muscle activation occurring with specific weight-bearing exercises. The purpose of this study was to investigate the level of activation of the gluteus medius muscle as measured by electromyographic (EMG) signal amplitude in 5 weight-bearing exercises. Twenty healthy subjects aged 21 to 30 years participated in the study. The EMG surface electrodes were positioned over the muscle belly of the gluteus medius. Subjects performed 5 exercises that consisted of bilateral stance, single limb stance, single limb stance on both a firm surface and an Airex cushion, and single limb squat on a firm surface and an Airex cushion. Statistical differences (rho < 0.05) in gluteus medius EMG values were found between single limb stance as compared with double limb stance, and single limb squat as compared with single limb stance. Single limb stance places more demands on the gluteus medius than double limb stance, whereas single limb squats are more demanding than single limb stance. Although exercises performed on an Airex cushion produced greater EMG values as compared with a firm surface, the difference was not statistically significant. The results, however, suggest that if the goal is to increase the challenge to the gluteus medius, dynamic, single limb exercises performed on unstable surfaces, such as a balance cushion, may place greater demands on the gluteus medius than similar exercises performed on stable surfaces.