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Shoulder proprioception: latent muscle reaction times
T J Brindle1, J Nyland, R Shapiro
1Section of Sports Medicine, University of Kentucky, Kentucky Clinic, Lexington 40536, USA.
Medicine and Science in Sports and Exercise
|October 20, 1999
Summary
Trained overhead athletes exhibit altered rotator cuff muscle reaction times, potentially increasing injury risk. This study identifies key electromyographic (EMG) differences in latent muscle reaction timing (LMRT) during internal rotation perturbation.
Area of Science:
- Sports Medicine
- Biomechanics
- Neuromuscular Physiology
Background:
- Overhead throwing athletes develop unique neuromuscular adaptations.
- Understanding rotator cuff muscle response to perturbation is crucial for injury prevention.
Purpose of the Study:
- To compare electromyographic (EMG) differences in latent muscle reaction timing (LMRT) of the rotator cuff.
- To investigate responses between trained overhead throwers and control subjects.
- To analyze reactions to sudden internal rotation perturbation.
Main Methods:
- Electromyography (EMG) was used to assess rotator cuff LMRT.
- 15 trained throwers and 15 untrained subjects were tested.
- Subjects resisted sudden internal rotation forces in a seated position.
Main Results:
- Trained throwers showed slower infraspinatus and teres minor LMRT.
- Supraspinatus and posterior deltoid activation duration was decreased in throwers.
- Significant differences (P < 0.05) were observed in LMRT and muscle activation.
Conclusions:
- Rotator cuff muscles in trained throwers may be downregulated during perturbation.
- These adaptations may enhance throwing velocity but increase pathology risk.
- Altered LMRT suggests neuromuscular imbalance in overhead athletes, relevant for rehabilitation.