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Changes in torque complexity with fatigue are related to motor unit behaviour.
João Sá Gomes1, João Henriques Oliveira2, Philipp Bauer1
1Egas Moniz Center for Interdisciplinary Research (CiiEM), Egas Moniz School of Health and Science, Quinta da Granja, 2829-511, Monte da Caparica, Portugal.
Scientific Reports
|April 15, 2025
Summary
Neuromuscular fatigue reduces torque complexity, indicating decreased adaptability. This change is linked to alterations in motor unit firing rate and action potential amplitude, highlighting fatigue
Area of Science:
- Physiology
- Neuromuscular Science
- Biomechanics
Background:
- Physiological complexity is linked to neuromuscular system adaptability and functional capacity.
- Understanding how neuromuscular fatigue affects this complexity is crucial for assessing system performance.
Purpose of the Study:
- To investigate the relationship between changes in torque complexity and neuromuscular fatigue.
- To explore the association between torque complexity alterations and specific motor unit parameters.
Main Methods:
- Healthy adults performed knee extension maximal voluntary isometric contractions and submaximal contractions.
- A fatiguing protocol involving concentric and eccentric contractions was administered.
- Torque signals were analyzed for complexity using an entropy measure, alongside motor unit parameters.
Main Results:
- Torque complexity significantly decreased after the fatiguing protocol, indicating reduced adaptability.
- Alterations in torque complexity correlated strongly with pre-fatigue motor unit firing rates and peak action potential amplitudes.
- Specific correlations were observed for vastus lateralis and medialis muscles.
Conclusions:
- Neuromuscular fatigue leads to a reduction in torque complexity, signifying a less adaptable neuromuscular system.
- Changes in torque complexity during fatigue are associated with underlying motor unit behavior.
- This study provides insights into the neuromuscular basis of fatigue and adaptability.
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