Factors associated with electrical stimulation-induced performance fatigability are dependent upon stimulation location

Thomas B. Inns, Daniel McCormick, Carolyn A. Greig, Philip J. Atherton, Bethan E. Phillips, Mathew Piasecki*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Neuromuscular electrical stimulation (NMES) is increasingly viewed as a central tenet to minimise muscle loss during periods of disuse/illness – typically applied directly over a muscle belly. Peripheral nerve stimulation (PNS) is afforded less attention, despite providing a more global contractile stimulus to muscles. We investigated NMES versus PNS in relation to performance fatigability and peripheral contributions to voluntary force capacity. Two fatigue protocols were assessed separately: (1) over-quadriceps NMES and (2) peripheral (femoral) nerve stimulation (PNS). Before and after each session, a maximal voluntary contraction (MVC) was performed to assess force loss. Knee-extensor force was measured throughout to assess contractile function in response to submaximal electrical stimulation, and M-wave features quantified myoelectrical activity. NMES and PNS induced similar voluntary (MVC, NMES: −12 ± 9%, PNS: −10 ± 8%, both P < 0.001) and stimulated (NMES: −45 ± 12%, PNS −27 ± 27%, both P < 0.001) force reductions. Although distinct between protocols, myoelectrical indicators of muscle recruitment (M-wave area and amplitude) and nerve conduction time did not change throughout either protocol. Myoelectrical propagation speed, represented as M-wave duration, and the delay before muscle relaxation began both progressively increased during NMES only (P < 0.05 and P < 0.001, respectively). NMES myoelectrical changes suggested performance fatigability, indicating activation of superficial fibres only, which was not observed with PNS. This suggests PNS recruits a wider pool of muscle fibres and motor units and is a favourable alternative for rehabilitation. Future work should focus on implementing PNS interventions in clinically relevant scenarios such as immobilisation, care homes and critical illness.

Original languageEnglish
Pages (from-to)828-836
Number of pages9
JournalExperimental Physiology
Volume106
Issue number4
Early online date9 Mar 2021
DOIs
Publication statusPublished - 1 Apr 2021

Bibliographical note

Funding Information:
informationThis work was supported by the Medical Research Council [grant number MR/P021220/1] as part of the MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research awarded to the Universities of Nottingham and Birmingham, and was supported by the NIHR Nottingham Biomedical Research Centre. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

Publisher Copyright:
© 2021 The Authors. Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society

Keywords

  • electromyography
  • fatigue
  • myoelectrical characteristics
  • neuromuscular electrical stimulation
  • skeletal muscle

ASJC Scopus subject areas

  • Physiology
  • Nutrition and Dietetics
  • Physiology (medical)

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