Influence of vertical and horizontal whole-body vibration on selected muscles tension of employees age 50+ in relation to professional exposure to vibration (pilot study)

The pilot study on changes of selected muscles tension caused by vertical and horizontal whole-body vibration focused on employees belonging to two professional (occupational) groups. One of these groups consisted of men aged 50 years professionally exposed to vibration and the second were men not exposed to vibration at the workplace. Tests have been conducted in two series on special designed laboratory test bench for simulation of exposure to whole-body vibration. During the I series of tests, vertical vibration had acted on subjects and during II series horizontal lateral vibration had acted. The EMG signals were registered from muscles of the shoulder girdle and lower back, both sites of the body. Muscles tension values obtained during I and II series indicates that there are no statistical significant differences between reaction of subjects on vertical and horizontal vibration. However slightly lower EMG RMS values during II series were noticed. Exposure to whole-body vibration may cause changes in muscle tension both in employees (aged 50 years and older) occupationally exposed to vibration and not exposed to vibration. The observed changes vary in both groups of subjects. In occupationally exposed to vibration subjects the impact of exposure to vibration on muscle tension is less than in reference group.