Effects of Whole-Body Vibration Training with Different Body Positions and Amplitudes on Lower Limb Muscle Activity in Middle-Aged and Older Women

Abstract

Purpose The present study was designed to investigate the electromyographic (EMG) response in leg muscles to whole-body vibration while using different body positions and vibration amplitudes. Methods: An experimental study with repeated measures design involved a group of community-dwelling middle-aged and older women (n = 15; mean age=60.8 ± 4.18 years). Muscle activity of the gluteus maximus (GM), rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), and gastrocnemius (GS) was measured by surface electromyography, which participants were performing three different body positions during three WBV amplitudes. The body positions included static semi-squat, static semi-squat with elastic band loading, and dynamic semi-squat. Vibration stimuli tested were 0 mm, 2 mm, and 4 mm amplitude and 30 Hz frequencies. And the maximum accelerations produced by vibration stimuli with amplitudes of 2 mm and 4 mm are approximately 1.83 g and 3.17 g. Results: Significantly greater muscle activity was recorded in VL, BF, and GS. When WBV was applied to training, compared with the same training without WBV ( P .05). Conclusions: The EMG amplitudes of most leg muscles tested were significantly greater during WBV exposure than in the no-WBV condition. The dynamic semi-squat 4 mm whole-body vibration training is recommended for middle-aged and older women to improve lower limb muscle strength and function.