http://jneuroengrehab.biomedcentral.com/articles/10.1186/s12984-016-0152-7
- Junhong ZhouEmail author,
- Lewis Lipsitz,
- Daniel Habtemariam and
- Brad Manor
Journal of NeuroEngineering and Rehabilitation201613:44
DOI: 10.1186/s12984-016-0152-7
© Zhou et al. 2016
Received: 23 December 2015
Accepted: 22 April 2016
Published: 3 May 2016
Abstract
Background
Postural control requires
numerous inputs interacting across multiple temporospatial scales. This
organization, evidenced by the “complexity” contained within standing
postural sway fluctuations, enables diverse system functionality.
Age-related reduction of foot-sole somatosensation reduces standing
postural sway complexity and diminishes the functionality of the
postural control system. Sub-sensory vibrations applied to the foot
soles reduce the speed and magnitude of sway and improve mobility in
older adults. We thus hypothesized that these vibration-induced
improvements to the functionality of the postural control system are
associated with an increase in the standing postural sway complexity.
Method
Twelve healthy older adults
aged 74 ± 8 years completed three visits to test the effects of foot
sole vibrations at 0 % (i.e., no vibration), 70 and 85 % of the sensory
threshold. Postural sway was assessed during eyes-open and eyes-closed
standing. The complexity of sway time-series was quantified using
multiscale entropy. The timed up-and-go (TUG) was completed to assess
mobility.
Results
When standing without
vibration, participants with lower foot sole vibratory thresholds
(better sensation) had greater mediolateral (ML) sway complexity (r
2 = 0.49, p < 0.001), and those with greater ML sway complexity had faster TUG times (better mobility) (r
2 = 0.38, p
< 0.001). Foot sole vibrations at 70 and 85 % of sensory threshold
increased ML sway complexity during eyes-open and eyes-closed standing (p
< 0.0001). Importantly, these vibration-induced increases in
complexity correlated with improvements in the TUG test of mobility (r
2 = 0.15 ~ 0.42, p < 0.001 ~ 0.03).
Conclusions
Sub-sensory foot sole
vibrations augment the postural control system functionality and such
beneficial effects are reflected in an increase in the physiologic
complexity of standing postural sway dynamics.
Full article at link, you can quiz your doctor on it to explain 'stochastic resonance' and the 'complexity theory of aging'.
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