Acute Neuromuscular Modulation Enhances Postural Control after Whole-body Vibration

The postural movement control determines performance of almost any kind of human movement. The current study aimed to investigate whether a short bout of whole-body vibration (WBV) can improve postural control. Effects were compared to a conventional balance training (BAL). During an instable one-legged stance, postural control was assessed in 22 healthy subjects before and after 2-min bouts of either WBV or BAL. Postural sway, antagonist co-contraction of selected lower limb muscles (soleus, gastrocnemius medialis, tibialis anterior, rectus femoris, biceps femoris) and soleus spinal excitability (H-reflexes) were recorded by means of posturography and electromyography, respectively. Postural sway was significantly reduced after WBV (p<.05). After both interventions, a reduction of H-reflexes (WBV -31%, BAL -14%, p<.05), M-waves (WBV -22%, BAL -19%, p<.05) as well as shank muscle co-contraction was observed (WBV up to -18%, BAL up to -20%, p<.05). Thigh muscle co-contraction was only diminished after BAL (-17%, p<.05). Postural sway changes correlated positively with reflex amplitude changes (p<.05). Thus, greater inhibition in spinal excitability (after WBV), but not diminished thigh muscle co-contraction (after BAL) are accompanied by postural sway reduction. With the benefit of being (task-) unspecific and easy to apply, WBV represents a possible intervention to improve postural control.