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Updated: Aug 7, 2026
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Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Exertion dependent alternations in force fluctuation and limb acceleration during sustained fatiguing contraction
Chien-Ting Huang1, Ing-Shiou Hwang, Chien-Chun Huang
1Department of Physical Therapy, College of Medicine, National Cheng Kung University, 701, Tainan, Taiwan.
European Journal of Applied Physiology
|June 14, 2006
Summary
Muscle fatigue affects limb acceleration (LA) differently based on exertion levels. Lower exertion (25% MVC) increased LA signals, while higher exertion (75% MVC) did not significantly alter LA spectral peaks.
Area of Science:
- Biomechanics
- Neuroscience
- Physiology
Background:
- Muscle fatigue is a complex phenomenon impacting motor control.
- Understanding exertion-dependent changes in physiological signals is crucial for diagnosing fatigue.
Purpose of the Study:
- To investigate how varying exertion levels (25% vs. 75% MVC) influence electromyography (EMG), force fluctuation (FF), and limb acceleration (LA) during isometric contractions.
- To differentiate the contributions of central and peripheral factors to muscle fatigue based on physiological signal alterations.
Main Methods:
- Fifteen volunteers performed sustained index finger abduction at 25% and 75% maximal voluntary contractions (MVC) until task failure.
- Monitored temporal/spectral features of force, first dorsal interosseous (FDI) muscle activity (EMG), and index/hand acceleration (LA).
Main Results:
- Lower exertion (25% MVC) led to increased EMG, FF, and LA signals, with LA showing the largest amplitude increase.
- At 25% MVC, enhanced metacarpophalangeal (MCP) joint coupling and increased EMG-FF/EMG-LA coherences (8-12 Hz) were observed, alongside a spectral peak shift in LA.
- Higher exertion (75% MVC) did not significantly alter the LA spectral peak and conversely undermined EMG-FF/EMG-LA coherences and MCP joint coupling.
Conclusions:
- Limb acceleration (LA) is highly susceptible to muscle fatigue during sustained low-exertion contractions.
- Divergent physiological signal changes suggest distinct central and peripheral contributions to muscle fatigue at different exertion levels.
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