The effects of whole body vibration on balance, joint position sense and cutaneous sensation.

Whole body vibration (WBV) may enhance muscular strength and power but little is known about its influence on sensory-motor function. Vibration of a single muscle or tendon affects the afferent system in a manner that depends on amplitude and frequency. WBV stimulates many muscle groups simultaneously and the frequencies and amplitudes used are different from many of the studies on single musculotendinous units. We investigated the effects of WBV at two amplitudes on balance, joint position sense (JPS) and cutaneous sensation in young healthy subjects. Eighteen adults (24.3 ± 1.5 years, 15 females) were assessed before WBV (five 1 min bouts, 30 Hz) then immediately, 15 and 30 min afterwards. Two amplitudes (4 and 8 mm peak to peak) were investigated on different occasions. Standing balance was assessed with feet together and eyes closed, and standing on one leg with eyes open and closed. JPS at the knee and ankle was assessed by repositioning tasks while cutaneous sensation was recorded from six sites in the lower limb using pressure aesthesiometry. Neither amplitude affected JPS (P > 0.05). There were minimal effects on balance only in the vertical plane and only 30 min after WBV (P < 0.05). Low amplitude vibration only reduced sensation at the foot and ankle immediately after WBV (P < 0.008). High amplitude vibration impaired sensation at the foot, ankle and posterior shank for the entire test period (P < 0.008). In young healthy individuals WBV did not affect JPS or static balance, but reduced cutaneous sensation. These data may have implications for older and clinical populations with compromised postural control.