Influence of sex on the age‐related adaptations of neuromuscular function and motor unit properties in elite masters athletes

Abstract

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. r 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. r 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. r 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. r 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.

Molecular and neural adaptations to neuromuscular electrical stimulation; Implications for ageing muscle

“…Electromyography (EMG), the recording of electrical activity from muscle ( Mills, 2005 ), is widely accepted and used to study MU structure and function ( Heckman and Enoka, 2012 ; Piasecki et al, 2018a ; Piasecki et al, 2020 ). These methods range in complexity but largely involve surface based and/or intramuscular measures, able to generate representations of the ionic exchange across the muscle fibre membrane.…”

Near-Fibre Electromyography

“…Several previous studies (Allen et al 2015;Hourigan et al 2015;Piasecki et al 2016bPiasecki et al , 2016aPiasecki et al , 2020Power et al 2016;Gilmore et al 2017; have incorporated NFEMG parameters to demonstrate the effects of specific diseases or ageing on individual MUs. The focus of this paper is to utilise MUPs and NFMs extracted from simulated EMG signals and those obtained from human muscles to explicitly describe and evaluate a range of NFEMG methods and parameters used to investigate neuromuscular alterations, including a new measure of NMJ instability, NFM segment jitter.…”

Evaluating skeletal muscle function across the lifespan: Age as a continuous variable

“…Although age‐ and inactivity‐related declines in neuromuscular function are known, in this issue of The Journal of Physiology , Piasecki et al . (2021) report the age‐related trajectory of neuromuscular function and motor unit adaptations in the tibialis anterior of both male and female masters athletes aged 44–88 years. Using intramuscular electromyography (EMG), they demonstrate a steady age‐related decline in muscle function (maximal torque and balance) and evidence of neuromuscular instability in both sexes.…”

“…Moreover, Piasecki et al . (2021) examined neuromuscular function at 25% of maximal isometric voluntary contraction. Previous work has demonstrated that age‐related differences in motor unit firing rate increase with contraction intensity (Kamen & Knight, 2004).…”

“…Although the results obtained are of interest to the field of ageing, perhaps more importantly, the approach employed Piasecki et al . (2021) provides a template that could be emulated with respect to interrogating neuromuscular trajectories of other groups of people, particularly sedentary individuals, those with co‐morbidities or those experiencing prolonged bedrest. Specifically, comparing the progression of neuromuscular dysfunction in sedentary and active adults across the lifespan would allow researchers to parse the effects of ageing and activity.…”