Optimaization of Neuromuscular Activation in Whole Body Vibration – Effect of Type, Frequency, Amplitude and Body Position

Although there is substantial amount of scientific papers dealing with whole body vibration (WBV), only few investigate optimal neuronal activation as a function of frequency, amplitude or body position. The present study aims to determine the influence of WBV parameters on the neuronal activation in order to identify those conditions that cause a high neuromuscular activation and therefore provide optimal training conditions. In a randomized cross-over study, the EMG activity of six leg muscles was analyzed in 18 subjects with respect to the following determinants: (1) vibration type (rotational (RV) vs. synchronous vibration (SV), (2) frequency (5–10–15–20–25–30 Hz), (3) amplitude (2 vs. 4mm), (4) knee flexion angle (10°–30°–60°) and stance condition (forefoot vs. normal stance). The results are: (1) EMG activity in RV was enhanced compared to SV (P<0.05); enhanced (2) frequency or (3) amplitude caused a progressive increase in EMG activity (P<0.05). (4) The EMG activity was highest for the knee extensors when the knee joint was 60° flexed (P<0.05) and for the plantar flexors in the forefoot stance condition (P<0.05). In conclusion, the combination of high vibration frequencies and amplitudes on a RV platform led to highest EMG activities and hence, is supposed to provide a favourable parameter setting for WBV training. With respect to body posture, a knee flexion of 60° and forefoot stance appear to be beneficial for the knee extensors and the plantar flexors, respectively.