Acute effects of transient vertical whole-body vibration.

The question as to whether shock-type whole-body vibration causes increasingly acute strain was investigated. Random vibrations were superimposed with shocks differing in amplitude and in number per unit of time in a systematic manner. The weighted root mean square (rms) acceleration was kept constant in all over the varied experiments. A total of 17 men were exposed to vibration from an electrohydraulic simulator. The following strain criteria were used: biodynamic behavior of the trunk and the head, electrical activity of the muscles of the back and the neck, subjective sensation, skin temperature in the lumbar area and visual and tracking performance. It was found that increasing shock amplitude and, in some experiments, also increasing numbers of shocks led to increasingly acute effects that varied, depending on the kind of shock used. New methods should be developed for the assessment of transient vibration that are better than the existing standards.