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Distinct brain activation patterns for human maximal voluntary eccentric and concentric muscle actions
Yin Fang1, Vlodek Siemionow, Vinod Sahgal
1Department of Biomedical Engineering/ND20, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Brain Research
|September 18, 2004
Summary
Maximal eccentric muscle contractions require greater central nervous system (CNS) cortical activation and longer preparation time than maximal concentric contractions, despite lower muscle activity. This suggests unique CNS control for eccentric actions.
Area of Science:
- Neuroscience
- Exercise Physiology
- Biomechanics
Background:
- Eccentric muscle contractions produce more force and cause greater muscle damage than concentric contractions.
- Previous studies show electroencephalogram (EEG)-derived movement-related cortical potential (MRCP) differs between submaximal eccentric and concentric actions.
- The central nervous system (CNS) control for maximal-effort eccentric contractions remains unclear.
Purpose of the Study:
- To investigate differences in MRCP signals between maximal voluntary eccentric and concentric elbow flexor contractions.
- To determine if CNS control strategies vary for high-intensity eccentric versus concentric movements.
Main Methods:
- Eight volunteers performed maximal voluntary eccentric and concentric elbow flexor contractions using a Kin-Com isokinetic dynamometer.
- Scalp EEG (62 channels), force, joint angle, and electromyography (EMG) signals were recorded.
- Two-dimensional brain maps of MRCPs were generated to analyze spatial and temporal distributions.
Main Results:
- MRCP-indicated cortical activation was greater in amplitude and spatial extent for maximal eccentric contractions compared to concentric contractions.
- Eccentric movements exhibited significantly longer early preparation times and greater cortical activity magnitude during movement execution.
- Despite lower muscle activity during eccentric actions, the brain showed increased activation.
Conclusions:
- Maximal eccentric contractions necessitate distinct CNS control strategies compared to maximal concentric contractions.
- The observed differences in cortical activation and preparation time may reflect the higher injury risk, difficulty, and unique motor unit recruitment in eccentric actions.
- These findings highlight the complex neural adaptations involved in controlling high-intensity eccentric muscle actions.