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Concentric versus eccentric isokinetic strengthening of the rotator cuff. Objective data versus functional test
T S Ellenbecker1, G J Davies, M J Rowinski
1Department of Physical Therapy, University of Wisconsin, La Crosse.
The American Journal of Sports Medicine
|January 1, 1988
Summary
Concentric isokinetic training significantly improved shoulder strength and tennis serve velocity in college players. Eccentric training showed fewer benefits, indicating specificity in strength gains for tennis performance.
Area of Science:
- Sports Medicine
- Biomechanics
- Exercise Physiology
Background:
- Shoulder strength is crucial for tennis performance, particularly in serving.
- Understanding the specificity of training (concentric vs. eccentric) is important for optimizing athlete development.
Purpose of the Study:
- To compare the effects of 6-week concentric versus eccentric isokinetic training on shoulder rotation strength.
- To examine the transfer of training effects (overflow) and specificity on concentric and eccentric strength.
- To evaluate the impact of training on functional performance, specifically maximal tennis serve velocity.
Main Methods:
- Twenty-two college varsity tennis players were divided into two groups: one undergoing eccentric isokinetic training, the other concentric isokinetic training.
- Subjects were pretested and posttested for both concentric and eccentric shoulder rotation strength at various speeds.
- Maximal tennis serve velocity was measured using high-speed cinematography before and after the 6-week training intervention.
Main Results:
- Both training groups showed significant gains in concentric peak torque and peak torque to body weight ratio (P < 0.005).
- The concentric training group demonstrated significant eccentric strength gains at selected speeds (P < 0.05 and P < 0.005).
- The concentric training group exhibited a significant increase in maximal serve velocity (P < 0.005), while the eccentric group did not show significant improvement (P > 0.01).
Conclusions:
- Concentric isokinetic training leads to significant improvements in both concentric and eccentric shoulder strength, as well as functional performance in tennis serves.
- Eccentric isokinetic training primarily enhances eccentric strength but shows limited transfer to concentric strength or serve velocity.
- These findings suggest that concentric training protocols may be more beneficial for enhancing overall shoulder strength and tennis-specific performance.