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Neuromuscular fatigue reduces force responsiveness when controlling leg external forces
Pawel Kudzia1, James M Wakeling2, Stephen N Robinovitch2
1Department of Engineering Science, Simon Fraser University, Burnaby, British Columbia, Canada.
Physiological Reports
|August 22, 2025
Summary
Neuromuscular fatigue slows leg force adjustments but maintains accuracy during agile movements. This suggests the nervous system uses compensatory strategies to preserve precision despite reduced muscle strength.
Area of Science:
- Neuromuscular Control
- Biomechanics
- Motor Learning
Background:
- Agile movement relies on precise control of ground reaction forces.
- The effects of neuromuscular fatigue on this force modulation are not fully understood.
Purpose of the Study:
- To investigate how leg muscle fatigue impacts the nervous system's ability to modulate vertical ground reaction forces.
- To determine if fatigue impairs responsiveness and/or accuracy in force control.
Main Methods:
- Eighteen healthy participants performed force-matching tasks using a custom apparatus.
- Fatigue was induced via sustained submaximal contractions.
- Responsiveness (rise time, bandwidth) and accuracy (overshoot, steady-state error, variability) were quantified before and after fatigue.
Main Results:
- Maximal voluntary contraction (MVC) force decreased by 26.1%.
- Responsiveness was impaired, with increased rise time (23.3%) and decreased bandwidth (25.2%).
- Force control accuracy remained largely unchanged, with only a transient decrease in overshoot.
Conclusions:
- Neuromuscular fatigue selectively impairs the speed of leg force adjustments.
- Accuracy of force control is preserved, potentially through compensatory neural strategies.
- This dissociation has implications for understanding motor control deficits and injury risk during fatigue.
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