Bed rest impairs the vestibular control of balance

Stuart Mackenzie, Craig Smith, Malcom Tremblay, Brian L Day, Raymond Reynolds*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Downloads (Pure)

Abstract

Prolonged bed rest impairs standing balance but the underlying mechanisms are uncertain. Previous research suggests strength loss is not the cause, leaving impaired sensorimotor control as an alternative. Here we examine vestibular control of posture in 18 male volunteers before and after 60 days of bed rest. Stochastic vestibular stimulation (SVS) was used to evoke sway responses before, 1 and 6 days after bed rest under different head yaw orientations. The directional accuracy and precision of these responses were calculated from ground reaction force vectors. Bed rest caused up to 63% increases in spontaneous standing sway and 31% reductions in leg strength, changes which were uncorrelated. The increase in sway was exacerbated when the eyes were closed. Mean directions of SVS-evoked sway responses were unaffected, being directed towards the anodal ear and rotating in line with head orientation in the same way before and after bed rest. However, individual trial analysis revealed 25%–30% increases in directional variability, which were significantly correlated with the increase in spontaneous sway (r = 0.48–0.71; P ≤ 0.044) and were still elevated on day 6 post-bed rest. This reveals that individual sway responses may be inappropriately oriented, a finding masked by the averaging process. Our results confirm that impaired balance following prolonged bedrest is not related to loss of strength. Rather, they demonstrate that the sensorimotor transformation process which converts vestibular feedback into appropriately directed balance responses is impaired.
Original languageEnglish
Pages (from-to)2985-2998
JournalThe Journal of Physiology
Volume602
Issue number12
Early online date20 May 2024
DOIs
Publication statusPublished - 15 Jun 2024

Keywords

  • accuracy
  • bed rest
  • electrical vestibular stimulation
  • precision
  • proprioceptive acuity

Fingerprint

Dive into the research topics of 'Bed rest impairs the vestibular control of balance'. Together they form a unique fingerprint.

Cite this