PMID- 33006148 OWN - NLM STAT- MEDLINE DCOM- 20210412 LR - 20221229 IS - 1469-7793 (Electronic) IS - 0022-3751 (Linking) VI - 599 IP - 1 DP - 2021 Jan TI - Influence of sex on the age-related adaptations of neuromuscular function and motor unit properties in elite masters athletes. PG - 193-205 LID - 10.1113/JP280679 [doi] AB - KEY POINTS: Masters athletes maintain high levels of activity into older age and allow an examination of the effects of aging dissociated from the effects of increased sedentary behaviour. Evidence suggests masters athletes are more successful at motor unit remodelling, the reinnervation of denervated fibres acting to preserve muscle fibre number, but little data are available in females. Here we used intramuscular electromyography to demonstrate that motor units sampled from the tibialis anterior show indications of remodelling from middle into older age and which does not differ between males and females. The age-related trajectory of motor unit discharge characteristic differs according to sex, with female athletes progressing to a slower firing pattern that was not observed in males. Our findings indicate motor unit remodelling from middle to older age occurs to a similar extent in male and female athletes, with discharge rates progressively slowing in females only. ABSTRACT: Motor unit (MU) remodelling acts to minimise loss of muscle fibres following denervation in older age, which may be more successful in masters athletes. Evidence suggests performance and neuromuscular function decline with age in this population, although the majority of studies have focused on males, with little available data on female athletes. Functional assessments of strength, balance and motor control were performed in 30 masters athletes (16 male) aged 44-83 years. Intramuscular needle electrodes were used to sample individual motor unit potentials (MUPs) and near-fibre MUPs in the tibialis anterior (TA) during isometric contractions at 25% maximum voluntary contraction, and used to determine discharge characteristics (firing rate, variability) and biomarkers of peripheral MU remodelling (MUP size, complexity, stability). Multilevel mixed-effects linear regression models examined effects of age and sex. All aspects of neuromuscular function deteriorated with age (P < 0.05) with no age x sex interactions, although males were stronger (P < 0.001). Indicators of MU remodelling also progressively increased with age to a similar extent in both sexes (P < 0.05), whilst MU firing rate progressively decreased with age in females (p = 0.029), with a non-significant increase in males (p = 0.092). Masters athletes exhibit age-related declines in neuromuscular function that are largely equal across males and females. Notably, they also display features of MU remodelling with advancing age, probably acting to reduce muscle fibre loss. The age trajectory of MU firing rate assessed at a single contraction level differed between sexes, which may reflect a greater tendency for females to develop a slower muscle phenotype. CI - (c) 2020 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society. FAU - Piasecki, Jessica AU - Piasecki J AUID- ORCID: 0000-0001-9758-6295 AD - Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, UK. FAU - Inns, Thomas B AU - Inns TB AUID- ORCID: 0000-0002-9876-4468 AD - Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK. FAU - Bass, Joseph J AU - Bass JJ AUID- ORCID: 0000-0002-8236-681X AD - Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK. FAU - Scott, Reece AU - Scott R AUID- ORCID: 0000-0001-7642-545X AD - Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, UK. FAU - Stashuk, Daniel W AU - Stashuk DW AUID- ORCID: 0000-0002-8072-8135 AD - Department of Systems Design Engineering, University of Waterloo, Ontario, Canada. FAU - Phillips, Bethan E AU - Phillips BE AD - Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK. FAU - Atherton, Philip J AU - Atherton PJ AUID- ORCID: 0000-0002-7286-046X AD - Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK. FAU - Piasecki, Mathew AU - Piasecki M AUID- ORCID: 0000-0002-7804-4631 AD - Clinical, Metabolic and Molecular Physiology, MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK. LA - eng GR - MR/K00414X/1/MRC_/Medical Research Council/United Kingdom GR - MR/P021220/1/MRC_/Medical Research Council/United Kingdom PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20201022 PL - England TA - J Physiol JT - The Journal of physiology JID - 0266262 SB - IM CIN - J Physiol. 2021 Jan;599(1):3-4. PMID: 33043454 CIN - J Physiol. 2021 Apr;599(7):1957-1959. PMID: 33491208 MH - Adult MH - Aged MH - Aged, 80 and over MH - Athletes MH - Electromyography MH - Female MH - Humans MH - Male MH - Middle Aged MH - *Motor Neurons MH - Muscle Contraction MH - Muscle Fibers, Skeletal MH - *Muscle, Skeletal OTO - NOTNLM OT - electromyography OT - master athlete OT - motor unit OT - neuromuscular function EDAT- 2020/10/03 06:00 MHDA- 2021/04/13 06:00 CRDT- 2020/10/02 05:48 PHST- 2020/08/18 00:00 [received] PHST- 2020/09/24 00:00 [accepted] PHST- 2020/10/03 06:00 [pubmed] PHST- 2021/04/13 06:00 [medline] PHST- 2020/10/02 05:48 [entrez] AID - 10.1113/JP280679 [doi] PST - ppublish SO - J Physiol. 2021 Jan;599(1):193-205. doi: 10.1113/JP280679. Epub 2020 Oct 22.