Article

Step-up exercises often are suggested for strengthening the hip
abductor muscles and improving balance in older adults. Little is known, however,
about whether the forward or lateral version of these exercises is best for
activating the hip abductor muscles. The purpose of this study was to
examine the electromyographic (EMG) amplitude of the gluteus medius (GM) muscles
bilaterally during forward and lateral step-up exercises. DESIGN: The study
design involved single-occasion repeated measures. METHODS: Twenty-seven
community-dwelling adults (7 men and 20 women) with a mean (SD) age of 79.4 (8.0)
years performed forward and lateral step-up exercises while the surface EMG
activity of the GM muscles was recorded bilaterally. Pressure switches and dual
forceplates were used to identify the ascent and descent phases. Subjects were
instructed to lead with the right lower extremity during ascent and the left
lower extremity during descent. Differences in normalized root-mean-square EMG
amplitudes with exercise direction (forward versus lateral) and phase (ascent
versus descent) were examined by use of separate repeated-measures analyses of
variance for the right and left lower extremities. The alpha level was set at
.05. RESULTS: Gluteus medius muscle EMG activity was significantly greater for
lateral than for forward step-up exercises for the left lower extremity during
the ascent phase and for both lower extremities during the descent phase. In
addition, right GM muscle EMG activity was significantly greater during ascent
than during descent for both exercise directions. LIMITATIONS: Study limitations
include use of a convenience sample and collection of limited information about
participants. CONCLUSIONS: Step-up exercises are effective in activating the GM
muscle, with lateral step-up exercises requiring greater GM muscle activation
than forward step-up exercises. Further study is needed to determine whether
exercise programs for hip abductor muscle strengthening in older adults should
preferentially include lateral over forward step-up exercises.

Langue : ANGLAIS