Effects of whole-body vibration on postural balance and proprioception in healthy young and elderly subjects: a randomized cross-over study

Aim. The aim of this paper was to investigate the effects of the whole-body vibration (WBV) intervention on neuromuscular performances in both young and elderly healthy subjects, taking into consideration the recommendations of the international standard for such exposure. Methods. Two groups of healthy subjects (9 young and 18 elderly) received the intervention, while standing on a side-alternating platform, during two exposure periods of 8 weeks each separated by a washout period of 8 weeks between those periods. The intervention (with or without exposure to vibration) was administered twice a week. Vibration was produced at 20 Hz with an unweighted acceleration of 11.2 m/s(2) rms in the first 4 weeks, and 22.3 m/s(2) rms, in the last 4 weeks. Blood pressure, heart rate, single leg stance time with closed eyes (SSCE), postural stability parameters and,knee joint position sense were measured before and after intervention and were compared. Results. In the young group, the post-intervention measurement values did not differ from the corresponding pre-intervention values. In the elderly group, SSCE at the right side significantly increased (P<0.014) after vibration intervention. The lateral sway (X-axis locus length) of postural stability parameter after WBV intervention tended to decrease in the elderly group (P=0.078). However, in both groups, pre- and post-intervention values of knee joint position sense were not significantly different. Conclusion. The used level of vibration showed some improvements in postural balance among the elderly. However, an effective level of vibration exposure should be decided for this purpose, considering the recommendations of the relevant standards.