- Whole body vibration exercise: are vibrations good for you?
Vibration is a mechanical stimulus characterised by an oscillatory motion. The biomechanical variables that determine its intensity are the frequency and amplitude. The extent of the oscillatory motion determines the amplitude (peak to peak displacement, in mm) of the vibration. The repetition rate of the cycles of oscillation determines the frequency of the vibration (measured in Hz).
Vibration has been studied extensively for its dangerous effects on humans at specific amplitudes and frequencies. On the other hand, recent work has suggested that low amplitude, low frequency mechanical stimulation of the human body is a safe and effective way to exercise musculoskeletal structures. In fact, increases in muscular strength and power in humans exercising with specially designed exercise equipment have been reported.1–7 In particular, the effects of whole body vibrations (WBVs) have been studied with subjects exercising on specially designed vibrating plates producing sinusoidal vibrations (fig 1). The exercise devices currently available on the market deliver vibration to the whole body by means of oscillating plates using two different systems: (a) reciprocating vertical displacements on the left and right side of a fulcrum; (b) the whole plate oscillating uniformly up and down.
WBV exercise devices deliver vibrations across a range of frequencies (15–60 Hz) and displacements from acceleration delivered can reach 15 g (where 1 g is the acceleration due to the Earth’s gravitational field or 9.81 m/s2). Considering the numerous combinations of amplitudes and frequencies possible with current technology, it is clear that there are a wide variety of WBV protocols that could be used on humans. Vibration exercise is quite a new topic in sport science. Many athletes and fitness and rehabilitation centres are using vibration in their exercise programmes, but current knowledge on appropriate safe and effective exercise protocols is very limited, and claims made by companies and pseudo-experts can be misleading.
The purpose of this review is to analyse the potential mechanisms by which muscles respond to vibration and to summarise current knowledge of the effects of vibration on human strength and power performance.
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