Short-term effects of whole-body vibration training on neuromuscular activity of muscles in important area in respect of osteoporotic fractures in maximal voluntary isometric contraction in young healthy women

Introduction: Electromyography (EMG) response of muscles to Whole Body Vibration (WBV) has most studied acutely in areas close to the vibration platform. While, chronic effects of WBV on EMG response of muscles in far areas from vibration plate and with therapeutic perspective has been neglected. This study aimed to investigate the EMG response of muscles in areas far from vibration plate and important from orthopedic view in osteoporotic fractures and at risk population like women. Materials and Methods: Twelve nonathletic healthy young women (mean age ± SD; 25.66 ± 2.71 years) were participated in the one-blind controlled trial study design. They all enrolled to the WBV (static semi squat training + vibration) (vertical vibration, 30 Hz, 3mm) and placebo (static semi squat training) groups, randomly. Training protocol was similar in both groups except of WBV machine set as off in placebo group. EMG tests of muscles (lumbar erector spine (ES), Gluteous maximus (G.max), Rectus femoris (RF)) were carried out before and after twelve sessions of training and root mean square and median frequency were extracted for statistical analysis. Results: WBV effects on RMS of ES (P = 0.017) and G.max (P = 0.014), as well as median frequency of ES (P = 0.020) increased than before training. The net effect of WBV compared with placebo increased statistically only in RMS of G.max muscle (P < 0.001) and this increase was more than other two muscles, significantly (P = 0.001). Conclusion: The results indicate the positive net effect of twelve sessions of WBV training on amplitude of muscle activity in G.max. This muscle is far from vibration plate and its strengthening can impose physiologic loading on the greater trochanter, cause likely to strengthen it and prevent osteoporotic fractures in this area. However, the relevance of this finding has to be further investigated in other studies and population like the postmenopausal women. Keywords: WBV training, Women, RMS, Median frequency, EMG, Osteoporosi