Effects of bilateral Achilles tendon vibration on postural orientation and balance during standing

Objective Altering proprioceptive information in the lower limbs by vibration produces direction-specific falling and postural instability, which can persist after vibration stops. The objectives of this study were to describe the changes in trunk and lower limbs postural orientation and muscles activities during and after the end of bilateral Achilles tendon vibration (TV). Methods Twelve healthy young subjects were exposed to 30 s periods of TV while blindfolded. Whole-body kinematics, kinetics and EMG of eight lower limb and trunk muscles were recorded prior, during and 5 or 25 s after TV. Results TV during quiet standing produced a whole-body backward shift characterized by greater extension in the trunk and lower limbs. Five seconds after TV, two trends of recovery could be observed, either an overcorrection or undercorrection of the initial position. Conclusions A continuum of postural orientations are adopted during and after vibration and the movements are not restricted to the ankle joints, despite the local nature of the proprioceptive stimulation. Significance The widespread influence of vibration as a proprioceptive stimulation when assessing its effects on posture and balance needs to be considered. Further studies should include whole-body analyses to document more thoroughly the postural strategies for balance maintenance during vibration.