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Fatigue- and Training-Related Differences in Muscle Activation and Coordination
Paulo D G Santos1,2, João R Vaz3, Miguel Gomes1,2
1Neuromuscular Research Lab, Faculty of Human Kinetics, University of Lisbon, Lisbon, Portugal.
International Journal of Sports Medicine
|November 26, 2025
Summary
Training status significantly impacts acute fatigue responses. Strength-trained individuals show different muscle activation and coordination adaptations compared to untrained individuals after fatiguing exercise.
Area of Science:
- Exercise Physiology
- Neuromuscular Physiology
- Sports Science
Background:
- Fatigue affects muscle activation and coordination, but how training status influences these responses is unclear.
- Understanding acute fatigue adaptations is crucial for optimizing training and performance.
Purpose of the Study:
- To investigate differences in neuromuscular responses to fatigue between strength-trained and untrained individuals.
- To compare changes in force production, muscle activation, and intermuscular coordination before and after a fatiguing protocol.
Main Methods:
- 28 participants (strength-trained vs. untrained) performed isometric leg-press contractions.
- Evaluated peak force, rate of force development, and electromyography (EMG) of seven lower-limb muscles.
- Assessed EMG amplitude, rate of EMG rise, and intermuscular coherence before and after a back-squat fatiguing protocol.
Main Results:
- Strength-trained individuals had higher baseline force and rate of force development.
- Fatigue reduced force production in both groups, with a greater decrease in strength-trained individuals.
- EMG amplitude increased in both groups, while the rate of EMG rise differed between groups.
- Intermuscular coherence patterns varied between trained and untrained individuals and were affected differently by fatigue.
Conclusions:
- Training status alters acute responses to fatigue, influencing agonist muscle activation and coordination.
- Differences in neuromuscular control strategies emerge between strength-trained and untrained individuals under fatiguing conditions.
- Fatigue impacts muscle coordination differently based on training background and muscle pair relationships.
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