Flaminia Carlucci: Acute residual effects of a single session of whole body vibration on the postural control in elderly women

by Flaminia Carlucci, C. Mazzà, A. Cappozzo (University of Rome Foro Italico, Italy)

Purpose: Chronic effects of whole body vibration training (WBVT) in enhancing postural control and reducing the risk of falls in the elderly people have been widely investigated, but relevant results are often controversial. Acute effects are even more unclear, since little data are available in the literature. Moreover, most of the previous studies used platforms that oscillate in the medio-lateral direction, and the acute effects of vertical oscillation remain unclear. The aim of this pilot study is to investigate the changes induced by the latter intervention on the balance of the elderly people.

Methods: Nine young (age 31 ± 4) and nine elderly (age 72 ± 4) female adults were exposed to one 12 min training session of WBVT (amplitude: 1.8 mm; frequency: 37 Hz). The protocol (1 min of vibration and 30 s of rest) consisted of a series of unloaded static and dynamic exercises: high squat, deep squat, wide stance squat and lunge. A force plate (Bertec Co.) was used to determine the centre of pressure trajectories (CoP) during four different 60 s posturographic sessions: before (T₀), immediately after (T₁), 15 min after (T₂) and 60 min after (T₃) the WBVT. The Sway Path (SP) and its medio-lateral (ML) and antero-posterior (AP) components were used to test the possible effects of the WBVT protocol on balance.

Results: No significant variations between pre- and post-training parameters were observed in the young people while in the elderly a reduction of about 11% of the SP values was observed at T₂ (546 ± 66 mm at T₀ 487 ± 33, p<0.02), which was again lost at T₃. This same difference was found in the ML but not in the AP component.

Discussion: These results suggest that WBVT can induce a transient and positive effect on postural control in the elderly in good health. This change may be ascribed to the enhancement of neuroregulatory functions, namely increased rate of motoneuron firing and better synchronisation of motor units activation. Further studies, however, are needed to investigate this phenomenon using a larger sample of subjects and different parameters of vibration (frequency and amplitude).

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