Muscle Stimulation via Whole Body Vibration for Postural Control Applications

  • Isotta Rigoni

Student thesis: Doctoral ThesisDoctor of Philosophy

Abstract

Although the ability to balance might feel effortless to the most, it should not be given for
granted as even the normal process of ageing can compromise it, jeopardising people physical
independence. It is therefore important to implement safe training routines that ultimately
improve postural control strategies.

We evaluated the suitability of whole body vibration (WBV) training –which induces muscle
contraction via the stimulation of muscle spindles - for postural control applications. First, we
tested the efficacy of different combinations of stimulation frequency and subjects’ posture in
eliciting a response from those muscles that play a key role for the implementation of postural
responses. Each combination was evaluated by jointly measuring the resulting muscular
activation and soft-tissue displacement. Then, we investigated how the selected WBV
stimulation affected the balance of healthy subjects. We evaluated the latter by analysing
centre of pressure trajectories, muscle and cortex activation and their respective interplay.

We found that high frequency vibrations, delivered to participants standing on their forefeet,
evoked the greatest contraction of the plantarflexors. Undisturbed balance recorded after such
stimulation was characterised by an increased sensitivity of muscle spindles. In line with the
latter, the communication between the periphery and the central nervous system (CNS)
increased after the stimulation and different muscle recruitment patterns were employed to
maintain balance. On the posturography side, stability was found to be compromised in the
acute term but seemed to have recovered over a longer term.

Together, these findings suggest that, if appropriately delivered, WBV has the potential to
stimulate the spindles of the plantarflexors. By doing so, vibration training seems to be able to
augment the communication between the proprioceptive organs and the CNS, on which the
system relies to detect and react to perturbations, leading to sensorimotor recalibration.
Date of Award2021
Original languageEnglish
SupervisorAntonio Fratini (Supervisor), James Wolffsohn (Supervisor) & Tecla Bonci (Supervisor)

Keywords

  • muscle spindle stimulation
  • undisturbed balance
  • electromyography (EMG)
  • coherence analyses (CMC/IMC)
  • posturography

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