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Age-dependent motor unit remodelling in human limb muscles

Piasecki, Mathew; Ireland, Alex; Jones, David A.; McPhee, Jamie S.

Authors

Alex Ireland

David A. Jones

Jamie S. McPhee



Abstract

Voluntary control of skeletal muscle enables humans to interact with and manipulate the environment. Lower muscle mass, weakness and poor coordination are common complaints in older age and reduce physical capabilities. Attention has focused on ways of maintaining muscle size and strength by exercise, diet or hormone replacement. Without appropriate neural innervation, however, muscle cannot function. Emerging evidence points to a neural basis of muscle loss. Motor unit number estimates indicate that by age around 71 years, healthy older people have around 40 % fewer motor units. The surviving low- and moderate-threshold motor units recruited for moderate intensity contractions are enlarged by around 50 % and show increased fibre density, presumably due to collateral reinnervation of denervated fibres. Motor unit potentials show increased complexity and the stability of neuromuscular junction transmissions is decreased. The available evidence is limited by a lack of longitudinal studies, relatively small sample sizes, a tendency to examine the small peripheral muscles and relatively few investigations into the consequences of motor unit remodelling for muscle size and control of movements in older age. Loss of motor neurons and remodelling of surviving motor units constitutes the major change in ageing muscles and probably contributes to muscle loss and functional impairments. The deterioration and remodelling of motor units likely imposes constraints on the way in which the central nervous system controls movements.

Journal Article Type Article
Publication Date 2016-06
Journal Biogerontology
Print ISSN 1389-5729
Electronic ISSN 1573-6768
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
Volume 17
Issue 3
Pages 485-496
APA6 Citation Piasecki, M., Ireland, A., Jones, D. A., & McPhee, J. S. (2016). Age-dependent motor unit remodelling in human limb muscles. Biogerontology, 17(3), 485-496. https://doi.org/10.1007/s10522-015-9627-3
DOI https://doi.org/10.1007/s10522-015-9627-3
Keywords Ageing; Gerontology; Geriatrics and Gerontology
Publisher URL https://link.springer.com/article/10.1007%2Fs10522-015-9627-3

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