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Corticospinal responses during passive shortening and lengthening of tibialis anterior and soleus in older compared to younger adults

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posted on 09.03.2021, 11:55 authored by Jakob SkarabotJakob Skarabot, Paul Ansdell, Glyn Howatson, Stuart Goodall, Rade Durbaba
Corticospinal responses have been shown to increase and decrease with passive muscle shortening and lengthening, respectively, as a result of changes in muscle spindle afferent feedback. The ageing sensory system is accompanied by a number of alterations that might influence the processing and integration of sensory information. Consequently, corticospinal excitability might be modulated differently whilst changing muscle length. In 10 older adults (66 ± 4 years), corticospinal responses (MEP/Mmax) were evoked in a static position, and during passive shortening and lengthening of soleus (SOL) and tibialis anterior (TA), and these data were compared to the re‐analysed data pool of 18 younger adults (25 ± 4 years) published previously. Resting motor threshold was greater in SOL compared to TA (P < 0.001), but did not differ between young and older (P = 0.405). No differences were observed in MEP/Mmax between the static position, passive shortening or lengthening in SOL (young: all 0.02 ± 0.01; older: 0.05 ± 0.04, 0.03 ± 0.02 and 0.04 ± 0.01, respectively; P = 0.298), and responses were not dependent on age (P = 0.090). Conversely, corticospinal responses in TA were modulated differently between the age groups (P = 0.002), with greater MEP/Mmax during passive shortening (0.22 ± 0.12) compared to passive lengthening (0.13 ± 0.10) and static position (0.10 ± 0.05) in young (P < 0.001), but unchanged in older adults (0.19 ± 0.11, 0.22 ± 0.11 and 0.18 ± 0.07, respectively; P ≥ 0.867). The present experiment shows that length‐dependent changes in corticospinal excitability in TA of the young are not evident in older adults. This suggests impaired sensorimotor response during muscle length changes in older age that might only be present in ankle flexors, but not extensors.

Funding

Research Development Fund for Doctoral Study

History

School

  • Sport, Exercise and Health Sciences

Published in

Experimental Physiology

Volume

105

Issue

3

Pages

419 - 426

Publisher

Wiley

Version

AM (Accepted Manuscript)

Rights holder

© The Authors. Experimental Physiology © The Physiological Society

Publisher statement

This is the peer reviewed version of the following article: ŠKARABOT, J. ... et al, 2020. Corticospinal responses during passive shortening and lengthening of tibialis anterior and soleus in older compared to younger adults. Experimental Physiology, 105 (3), pp.419– 426, which has been published in final form at https://doi.org/10.1113/EP088204. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Acceptance date

18/12/2019

Publication date

2020-02-07

Copyright date

2019

ISSN

0958-0670

eISSN

1469-445X

Language

en

Depositor

Dr Jakob Skarabot. Deposit date: 9 March 2021