A three-compartment muscle fatigue model accurately predicts joint-specific maximum endurance times for sustained isometric tasks

Laura A FREY-LAW; John M LOOFT; Jesse HEITSMAN

doi:10.1016/j.jbiomech.2012.04.018

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A three-compartment muscle fatigue model accurately predicts joint-specific maximum endurance times for sustained isometric tasks

Journal article

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A three-compartment muscle fatigue model accurately predicts joint-specific maximum endurance times for sustained isometric tasks

Laura A FREY-LAW, John M LOOFT and Jesse HEITSMAN

Journal of biomechanics, Vol.45(10), pp.1803-1808

2012

DOI: 10.1016/j.jbiomech.2012.04.018

PMCID: PMC3397684

PMID: 22579269

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https://www.ncbi.nlm.nih.gov/pmc/articles/3397684View

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Abstract

The development of localized muscle fatigue has classically been described by the nonlinear intensity-endurance time (ET) curve (Rohmert, 1960; El Ahrache et al., 2006). These empirical intensity-ET relationships have been well-documented and vary between joint regions. We previously proposed a three-compartment biophysical fatigue model, consisting of compartments (i.e. states) for active (M(A)), fatigued (M(F)), and resting (M(R)) muscles, to predict the decay and recovery of muscle force (Xia and Frey Law, 2008). The purpose of this investigation was to determine optimal model parameter values, fatigue (F) and recovery (R), which define the "flow rate" between muscle states and to evaluate the model's accuracy for estimating expected intensity-ET curves. Using a grid-search approach with modified Monte Carlo simulations, over 1 million F and R permutations were used to predict the maximum ET for sustained isometric tasks at 9 intensities ranging from 10% to 90% of maximum in 10% increments (over 9 million simulations total). Optimal F and R values ranged from 0.00589 (F(ankle)) and 0.0182 (R(ankle)) to 0.00058 (F(shoulder)) and 0.00168 (R(shoulder)), reproducing the intensity-ET curves with low mean RMS errors: shoulder (2.7s), hand/grip (5.6s), knee (6.7s), trunk (9.3s), elbow (9.9s), and ankle (11.2s). Testing the model at different task intensities (15-95% maximum in 10% increments) produced slightly higher errors, but largely within the 95% prediction intervals expected for the intensity-ET curves. We conclude that this three-compartment fatigue model can be used to accurately represent joint-specific intensity-ET curves, which may be useful for ergonomic analyses and/or digital human modeling applications.

Fundamental and applied biological sciences. Psychology

Vertebrates: osteoarticular system, musculoskeletal system

Striated muscle. Tendons

Applied physiology

Biological and medical sciences

Ergonomics. Work place. Occupational physiology

Medical sciences

Human physiology applied to population studies and life conditions. Human ecophysiology

Details

Title: Subtitle: A three-compartment muscle fatigue model accurately predicts joint-specific maximum endurance times for sustained isometric tasks
Creators: Laura A FREY-LAW - The University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, United States
John M LOOFT - The University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, United States
Jesse HEITSMAN - The University of Iowa, 1-252 Medical Education Building, Iowa City, IA 52242-1190, United States
Resource Type: Journal article
Publication Details: Journal of biomechanics, Vol.45(10), pp.1803-1808
DOI: 10.1016/j.jbiomech.2012.04.018
PMID: 22579269
PMCID: PMC3397684
NLM abbreviation: J Biomech
ISSN: 0021-9290
eISSN: 1873-2380
Publisher: Elsevier; Kidlington
Language: English
Date published: 2012
Academic Unit: Nursing; Physical Therapy and Rehabilitation Science
Record Identifier: 9984047891202771

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