Motor unit number estimates and neuromuscular transmission in the tibialis anterior of master athletes: evidence that athletic older people are not spared from age-related motor unit remodeling

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Piasecki, M ORCID: https://orcid.org/0000-0002-7804-4631, Ireland, A, Coulson, J ORCID: https://orcid.org/0000-0001-9758-6295, Stashuk, DW, Hamilton-Wright, A, Swiecicka, A, Rutter, MK, McPhee, JS and Jones, DA, 2016. Motor unit number estimates and neuromuscular transmission in the tibialis anterior of master athletes: evidence that athletic older people are not spared from age-related motor unit remodeling. Physiological Reports, 4 (19): e12987. ISSN 2051-817X

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Official URL: http://doi.org/10.14814/phy2.12987

Abstract

Muscle motor unit numbers decrease markedly in old age, while remaining motor units are enlarged and can have reduced neuromuscular junction transmission stability. However, it is possible that regular intense physical activity throughout life can attenuate this remodeling. The aim of this study was to compare the number, size, and neuromuscular junction transmission stability of tibialis anterior (TA) motor units in healthy young and older men with those of exceptionally active master runners. The distribution of motor unit potential (MUP) size was determined from intramuscular electromyographic signals recorded in healthy male Young (mean ± SD, 26 ± 5 years), Old (71 ± 4 years) and Master Athletes (69 ± 3 years). Relative differences between groups in numbers of motor units was assessed using two methods, one comparing MUP size and muscle cross‐sectional area (CSA) determined with MRI, the other comparing surface recorded MUPs with maximal compound muscle action potentials and commonly known as a “motor unit number estimate (MUNE)”. Near fiber (NF) jiggle was measured to assess neuromuscular junction transmission stability. TA CSA did not differ between groups. MUNE values for the Old and Master Athletes were 45% and 40%, respectively, of the Young. Intramuscular MUPs of Old and Master Athletes were 43% and 56% larger than Young. NF jiggle was slightly higher in the Master Athletes, with no difference between Young and Old. These results show substantial and similar motor unit loss and remodeling in Master Athletes and Old individuals compared with Young, which suggests that lifelong training does not attenuate the age‐related loss of motor units.

Item Type:	Journal article
Publication Title:	Physiological Reports
Creators:	Piasecki, M., Ireland, A., Coulson, J., Stashuk, D.W., Hamilton-Wright, A., Swiecicka, A., Rutter, M.K., McPhee, J.S. and Jones, D.A.
Publisher:	John Wiley
Date:	October 2016
Volume:	4
Number:	19
ISSN:	2051-817X
Identifiers:	Number Type 10.14814/phy2.12987 DOI
Rights:	© 2016 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	28 Jun 2018 10:44
Last Modified:	28 Jun 2018 10:44
URI:	https://irep.ntu.ac.uk/id/eprint/33937