Changes in Motor Unit Activity and Respiratory Oxygen Uptake during 6 Weeks of Progressive Whole-Body Vibration Combined with Progressive, High Intensity Resistance Training

Abstract

We hypothesized that the additional activation of motor units (MU) and the elevation of metabolic energy turnover resulting from whole-body vibration (WBV) superimposed to high intensity resistance training on a smith machine persist after 6 weeks of training with progressively increasing loads and vibration frequencies. Methods: Two Groups of healthy male subjects performed either 6 weeks of Resistive Vibration Exercise (RVE, squats and heel raises with WBV, n=13) or Resistive Exercise (RE using the same protocol, n=13). During the first (pre) and the last training session (post), we determined the oxygen uptake changes normalized to total training weight (∆V’O2/ttw) and the normalized MU activity from rectus femoris (squats) and gastrocnemius lateralis (heel raise) muscles filtered for vibration frequencies and harmonics (EMG/ttw). Results: At pre measurement, RVE induced higher EMG/ttw (squats) than RE alone (group effect, P=0.006). At post measurement, EMG/ttw was reduced (time effects between P=0.087 and P<0.001 for both Groups and exercises). At pre and post measurement, ∆V’O2/ttw was higher during RVE than during RE (group effects between P=0.005 and P=0.099 for both exercises). Conclusions: RVE permanently elevated metabolic energy turnover, although the initially observed additional MU activity by RVE could not be preserved in the working musculature.