Proceedings of The Physiological Society
University of Manchester (2010) Proc Physiol Soc 19, PC274
Whole body vibration; short-term effects on balance, proprioception and cutaneous sensation in healthy young adults
R. D. Pollock1, S. Provan1, F. C. Martin2, D. J. Newham1
1. Kings College London, London, United Kingdom. 2. Guys and St Thomas?
Whole body vibration (WBV) is an increasingly popular exercise modality due to reported improvements in muscle strength, power and bone strength although there are conflicting reports (Cardinale and Bosco 2003; de Ruiter et al. 2003). Effects on power as well as the stimulation of various sensory structures suggest there may be an influence on balance, proprioception and cutaneous sensation. With local ethics approval we investigated the effects of 5mins of high (4mm) and low (2mm) amplitude WBV on a rotating platform at 30Hz on balance, proprioception and cutaneous sensation. Knee and ankle proprioception during joint repositioning was determined using an electrogoniometer. Triaxial accelerometry was used to record standing balance (feet together, eyes closed (FTC); one leg, eyes open (1EO) and closed (1EC)) for 10s before WBV and immediately, 15 and 30mins after in 18 subjects (3 male, aged 24.3±1.5 years; height 1.72±0.1 m; mass 66.4±12.3 kg, mean±SD). Cutaneous sensation at the metatarsal (Met), lateral malleolus (Mal), anterior shank (AS), posterior shank (PS), patella (Pa) and mid-thigh (MT) was determined using Von Frey hairs. Statistical analysis was performed using repeated measures ANOVA with post hoc analysis and Freidmans ANOVA with Wilcoxon signed rank tests where appropriate. There was no significant effect of either amplitude on knee and ankle proprioception (2.7±1.8 and 1.1±0.6° angle error respectively) or on balance in the FTC (0.081±0.006, 0.071±0.005 and 0.047±0.003ms-2: anterior-posterior, AP, medial lateral, ML, and vertical, V, directions respectively) and 1EC positions (0.218 ± 0.192, 0.355 ± 0.316 and 0.384 ± 0.536 ms-2: AP, ML and V respectively). Thirty minutes later acceleration in the vertical plane improved by 23% during the first 5s (P<0.05) in the 1EO trial. High amplitude WBV significantly impaired sensation at the Met, Mal and PS for the entire test period (Fig 1; P<0.008). At the Met and Mal sensation reduced (P<0.008) immediately after low amplitude WBV but recovered by 15mins. There was no effect of either amplitude at any other site. Decreased afferent sensitivity may impair sensation after WBV only in the most distal body segments due to damping of vibration in more proximal ones. Plantar surface sensitivity is important for balance (Wang and Lin 2008) and impairments may increase the risk of falling in susceptible people. Minimal WBV effects on balance suggest little scope for improvement in those with no initial impairment (Torvinen et al. 2002) or during unchallenging tasks (Rittweger 2010). WBV appears to have no effect on proprioception. The implications of reduced sensation may be relevant for older and some clinical populations, particularly in more challenging positions, due to its detrimental effect on balance.
Where applicable, experiments conform with Society ethical requirements