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Motor impairment in the human hand following eccentric exercise
1School of Rehabilitation Therapy, Queen's University, Kingston, Ontario K7L 3N6, Canada. AL7@post.queensu.ca
European Journal of Applied Physiology
|April 26, 2001
Summary
Intense exercise caused significant motor impairment in the first dorsal interosseus (FDI) muscle, reducing strength and control. This suggests preferential injury to type II muscle fibers, impacting muscle function and coordination.
Area of Science:
- Neuromuscular physiology
- Exercise-induced muscle damage
Background:
- Muscle fatigue and injury can impair motor control.
- Understanding the specific mechanisms of muscle impairment is crucial for rehabilitation.
Purpose of the Study:
- To investigate the effects of fatiguing exercise on motor function and electromyography (EMG) of the first dorsal interosseus (FDI) muscle.
- To determine if exercise-induced motor impairment is associated with specific muscle fiber injury.
Main Methods:
- Subjects performed maximal contractions of the FDI muscle during stretching.
- Measurements included maximal torque, joint stabilization, isometric torque tracking variability, and FDI EMG.
- Tests were conducted pre-exercise and 24 hours post-exercise.
Main Results:
- Maximal abduction and flexion torque decreased by 19% and 15%, respectively.
- Joint stabilization ability reduced by 14%, and torque tracking variability increased by 30%.
- Median EMG frequency decreased, while mean rectified EMG increased significantly at lower contraction levels.
Conclusions:
- The observed motor impairments are consistent with preferential injury to type II muscle fibers in the FDI.
- Synergist muscles may compensate for injured FDI fibers during sub-maximal contractions.