Effects of Whole Body Vibration on the Neuromuscular Amplitude of Vastus Lateralis Muscle

The aim of this study was to investigate the effects of whole-body vibration (WBV) on vastus lateralis (VL) surface electromyographic (sEMG) amplitude during an isometric semi-squat exercise, using two different frequencies, and to verify the influence of additional filters on the analyzed sEMG signal's characteristics. Forty physically active women were randomly divided into two groups with 20 members each: one group performed an isometric semi-squat exercise at 30 Hz - while the other group performed the same exercise protocol at 50 Hz. The sEMG amplitude of the VL muscle was recorded during the exercise protocols in two conditions: with and without vibration. After removing vibration-induced artifacts using digital filters, sEMG amplitude of VL increased significantly (p < 0.05) without differences between the frequencies. The results of this study suggest that WBV at 30 Hz and 50 Hz increased the sEMG amplitude of the VL muscle during an isometric semi-squat exercise. Furthermore, applying sEMG filters during signal processing of WBV is necessary, because motion artifacts from the vibration frequencies may contribute to the contamination of the sEMG amplitude.