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Changes in limb dynamics during the practice of rapid arm movements
K Schneider1, R F Zernicke, R A Schmidt
1Department of Kinesiology, University of California, Los Angeles 90024-1568.
Journal of Biomechanics
|January 1, 1989
Summary
Practice enhances upper extremity motor coordination by altering joint moments. This study shows how learning a complex arm movement utilizes reactive phenomena to balance passive forces, improving performance.
Area of Science:
- Biomechanics
- Motor Control
- Human Movement Analysis
Background:
- Bernstein's hypothesis suggests practice refines motor coordination by altering muscular and passive joint moments.
- Understanding intralimb coordination is crucial for optimizing human movement.
- Previous research has explored the dynamics of human movement but requires further investigation into practice-related adaptations.
Purpose of the Study:
- To examine Bernstein's hypothesis regarding practice-induced changes in motor coordination.
- To analyze dynamical interactions among upper extremity joints during a practiced task.
- To investigate how intralimb coordination adapts with motor learning.
Main Methods:
- Dynamical analysis of a human multisegmental arm movement task.
- Recording high-speed ciné film and electromyography (EMG) of upper extremity muscles.
- Modeling the arm as interconnected rigid bodies to calculate joint moments.
Main Results:
- Subjects significantly reduced movement times with practice.
- Decreased movement times correlated with increased joint moments (excluding gravity).
- Changes in moment-time and EMG profiles indicated altered motor coordination, consistent with Bernstein's hypothesis.
Conclusions:
- Practice alters motor coordination by modifying the interplay between muscular and passive joint moments.
- Learned movements effectively utilize reactive phenomena to counterbalance passive-interactive moments.
- Findings support Bernstein's theory on the role of practice in refining intralimb coordination.