Between-day reliability of common muscle fatigue measures during a repeated upper limb fatigue protocol

Abstract

Neuromuscular fatigue manifestation is of interest in both basic neurophysiological and applied (e.g. sporting, ergonomics) contexts. A unique challenge in fatigue research is that experimental sessions often need to be collected across many days to allow for adequate recovery. The purpose of this study was to examine the between-day reliability of several surface electromyography- and strength-based fatigue measures in response to a repeated fatigue protocol. Twenty participants (10 M, 10 F) performed an isometric elbow flexion fatigue protocol on three different days. The reliability of commonly used amplitude- and frequency-based myoelectric and performance-based indicators of fatigue were assessed using traditional reliability assessment methods. Baseline MVC strength (N) demonstrated excellent between-day reliability (ICC_{A, 1}: 0.96, 95%CI[0.92, 0.98]) with good absolute reliability (SEM: 5.10%, MD₉₅: 14.1%). The absolute reliability of all slope-based fatigue measures was low. However, %MVC Slope (ICC: 0.67, [49, .82]), %MnPF Slope (ICC: 0.75, [.60, .87]), and endurance time (ICC: 0.60, [0.39, 0.77]) had poor/moderate to good relative reliability. Baseline MVC strength was shown to be very repeatable between days. Caution is recommended when using slope-based fatigue measures for cyclic repetitive upper limb tasks, as slope-based measures of muscle fatigue were shown to have low between-session reliability.

Keywords:

• Reliability
• fatigue
• electromyography

Disclosure statement

No potential conflict of interest was reported by the author(s).

Declaration of interest

The authors have no conflicts of interest to declare.

Additional information

Funding

This work was supported by the Centre of Research Expertise for the Prevention of Musculoskeletal Disorders (CRE-MSD) seed grant program; and the Natural Sciences and Engineering Research Council of Canada (NSERC) under discovery grant (RGPIN/005157-2020). The authors declare that the study sponsors were not involved in the collection, analysis, or interpretation of data, writing of the manuscript, or the decision to submit the manuscript for publication.

Notes on contributors

Michael W. B. Watterworth

Michael W. B. Watterworth is a first-year doctoral student at Ontario Tech University in the Faculty of Health Sciences (Kinesiology). He received his BHSc. (2020) and MHSc. degrees (2022) from Ontario Tech University.

Jeffrey D. Graham

Jeffrey D. Graham is currently a postdoctoral research fellow at Ontario Tech University in the Faculty of Health Sciences (Kinesiology). He received his Bachelor of Arts in Kinesiology (Honors Specialization) and Psychology (Major) at Western University in 2009, followed by his MSc (2011) and PhD (2015) in Kinesiology (Exercise and Health Psychology) from McMaster University.

Nicholas J. La Delfa

Nicholas J. La Delfa is currently an Associate Professor at Ontario Tech University in the Faculty of Health Sciences (Kinesiology). He received his B.Sc.kin (2009), MSc (2011) and PhD (2016) degrees in Kinesiology (biomechanics/ergonomics) from McMaster University, followed by a postdoctoral fellowship at the University of Waterloo.