Long-term endurance and power training may facilitate motor unit size expansion to compensate for declining motor unit numbers in older age

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Piasecki, M ORCID: https://orcid.org/0000-0002-7804-4631, Ireland, A, Piasecki, J ORCID: https://orcid.org/0000-0001-9758-6295, Degens, H, Stashuk, DW, Swiecicka, A, Rutter, MK, Jones, DA and McPhee, JS, 2019. Long-term endurance and power training may facilitate motor unit size expansion to compensate for declining motor unit numbers in older age. Frontiers in Physiology, 10: 449. ISSN 1664-042X

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Official URL: http://doi.org/10.3389/fphys.2019.00449

Abstract

The evidence concerning the effects of exercise in older age on motor unit (MU) numbers, muscle fiber denervation and reinnervation cycles is inconclusive and it remains unknown whether any effects are dependent on the type of exercise undertaken or are localized to highly used muscles. MU characteristics of the vastus lateralis (VL) were assessed using surface and intramuscular electromyography in eighty-five participants, divided into sub groups based on age (young, old) and athletic discipline (control, endurance, power). In a separate study of the biceps brachii (BB), the same characteristics were compared in the favored and non-favored arms in eleven masters tennis players. Muscle size was assessed using MRI and ultrasound. In the VL, the CSA was greater in young compared to old, and power athletes had the largest CSA within their age groups. Motor unit potential (MUP) size was larger in all old compared to young (p < 0.001), with interaction contrasts showing this age-related difference was greater for endurance and power athletes than controls, and MUP size was greater in old athletes compared to old controls. In the BB, thickness did not differ between favored and non-favored arms (p = 0.575), but MUP size was larger in the favored arm (p < 0.001). Long-term athletic training does not prevent age-related loss of muscle size in the VL or BB, regardless of athletic discipline, but may facilitate more successful axonal sprouting and reinnervation of denervated fibers. These effects may be localized to muscles most involved in the exercise.

Item Type:	Journal article
Publication Title:	Frontiers in Physiology
Creators:	Piasecki, M., Ireland, A., Piasecki, J., Degens, H., Stashuk, D.W., Swiecicka, A., Rutter, M.K., Jones, D.A. and McPhee, J.S.
Publisher:	Frontiers Research Foundation
Date:	26 April 2019
Volume:	10
ISSN:	1664-042X
Identifiers:	Number Type 10.3389/fphys.2019.00449 DOI
Rights:	© 2019 Piasecki, Ireland, Piasecki, Degens, Stashuk, Swiecicka, Rutter, Jones and McPhee. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Divisions:	Schools > School of Science and Technology
Record created by:	Jonathan Gallacher
Date Added:	09 May 2019 08:31
Last Modified:	09 May 2019 08:31
URI:	https://irep.ntu.ac.uk/id/eprint/36438