Postural control in elderly subjects participating in balance training.

The changes in postural control in elderly people after an 8-week training course were characterized. Static postural stability was measured during standing on a single force platform first with the eyes open and then with the eyes closed. Body sway was analysed on a force plate in groups of elderly and of young subjects. Half of the elderly subjects then took part in the training course. The posturographic measurements were repeated after the course. The sway in anteroposterior (AP) and mediolateral (ML) directions was subjected to spectral analysis. The frequency spectrum of the platform oscillations was calculated by fast Fourier transformation in the intervals 0.1-0.3, 0.3-1 and 1-3 Hz. It was found that the sway path was longer and the frequency power was higher in the elderly group. The training caused a significant improvement in functional performance, but a significantly longer sway path was observed after the training in the ML direction. The frequency analysis revealed a significantly higher power after 8 weeks without visual control in the ML direction in the training group in the low and the middle frequency bands. The results suggest that the participants' balance confidence and the control of ML balance improved in response to the training. The higher ML frequency power exhibited after the training may be indicative of a better balance performance. Thus, the increase in the sway path in this age group did not mean a further impairment of the postural control.