Vibration transmission to lower extremity soft tissues during whole-body vibration.

In order to evaluate potential risks of whole-body vibration (WBV) training, it is important to understand the transfer of vibrations from the WBV platform to the muscles. Therefore, the purpose of this study was to quantify the transmissibility of vibrations from the WBV platform to the triceps surae and quadriceps soft tissue compartments. Sixteen healthy, male participants were exposed to side-altering WBV at 2.5mm amplitude and frequencies of 10, 17 and 28 Hz. Acceleration signals were measured at the platform and at the soft tissue compartments using tri-axial accelerometers. Transmissibility of peak acceleration and peak amplitude for both tested soft tissue compartments was high at 10 Hz (2.1-2.3), moderate at 17 Hz (1.1-1.9) and low at 28 Hz (0.5-1.2). The average peak acceleration was 125.4 ms(-2) and 46.5 ms(-2) for the triceps surae and quadriceps at 28 Hz, respectively. The muscles' vibration frequency was equal to the input frequency of the WBV platform (p<0.05). The transfer of vibrations to the muscles is strongly dependent on the platform frequency and the particular muscle of interest. The acceleration measured at the triceps surae was higher than the corresponding accelerations related to soft tissue injury in animal studies but neither existing regulations nor the comparison to available animal studies seem appropriate to make inferences on injury risk. More realistic animal or computational muscle models may use the current data to evaluate potentially unwanted side effects of WBV training.