Effects of the availability of accurate proprioceptive information on older adults' postural sway and muscle co-contraction.
Title | Effects of the availability of accurate proprioceptive information on older adults' postural sway and muscle co-contraction. |
Publication Type | Journal Article |
Year of Publication | 2017 |
Authors | Craig, C. E., Calvert G. H. M., & Doumas M. |
Journal | Eur J Neurosci |
Volume | 46 |
Issue | 10 |
Pagination | 2548-2556 |
Date Published | 2017 Nov |
ISSN | 1460-9568 |
Keywords | Adaptation, Physiological, Adolescent, Adult, Aged, Aged, 80 and over, Electromyography, Female, Humans, Male, Muscle Contraction, Muscle, Skeletal, Postural Balance, Proprioception, Young Adult |
Abstract | During conditions of increased postural instability, older adults exhibit greater lower limb muscle co-contraction. This response has been interpreted as a compensatory postural strategy, which may be used to increase proprioceptive information from muscle spindles or to stiffen the lower limb as a general response to minimise postural sway. The current study aimed to test these two hypotheses by investigating use of muscle co-contraction during sensory transitions that manipulated proprioceptive input. Surface EMG was recorded from the bilateral tibialis anterior and gastrocnemius medialis muscles, in young (aged 18-30) and older adults (aged 68-80) during blind-folded postural assessment. This commenced on a fixed platform (baseline: 2 min), followed by 3 min on a sway-referenced platform (adaptation) and a final 3 min on a fixed platform again (reintegration). Sensory reweighting was slower in older adults, as shown by a significantly larger and longer postural sway after-effect once a stable platform was restored. Muscle co-contraction showed similar after-effects, whereby older adults showed a larger increase in co-contraction once the stable platform had been restored, compared to young adults. This co-contraction after-effect did not return to baseline until after 1 min. Our evidence for high muscle co-contraction during the reintroduction of veridical proprioceptive input suggests that increased co-contraction in older adults is not dependent on contemporaneous proprioceptive input. Rather, it is more likely that co-contraction is a general postural strategy used to minimise postural sway, which is increased during this sensory transition. Future research should examine whether muscle co-contraction is typically a reactive or anticipatory response. |
DOI | 10.1111/ejn.13703 |
Alternate Journal | Eur. J. Neurosci. |
PubMed ID | 28921721 |