A 6-week randomized-controlled field study: effect of isokinetic eccentric resistance training on strength, flexibility and muscle structure of the shoulder external rotators in male junior handball players.
Study Goal
To investigate the effects of 6-week eccentric isokinetic resistance training on strength, flexibility, and fiber architecture characteristics of the external rotators in junior male handball players compared to conventional preventive training.
Results Summary
The eccentric training group showed significant improvements in eccentric strength (+15%), fascicle length (+13% and +8% in supraspinatus and infraspinatus), and fractional anisotropy (+9% and +6%), but no change in range of motion. The control group did not show these improvements.
Population
Junior male handball players
Effective Dosage
Not specified
Duration
6 weeks
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
6-week eccentric isokinetic resistance training | increase | eccentric strength | junior male handball players | +15% | showed significant changes | #1 |
6-week eccentric isokinetic resistance training | increase | fascicle length of the supraspinatus muscle | junior male handball players | +13% | showed significant increases | #2 |
6-week eccentric isokinetic resistance training | increase | fascicle length of the infraspinatus muscle | junior male handball players | +8% | showed significant increases | #3 |
6-week eccentric isokinetic resistance training | increase | fractional anisotropy of the supraspinatus muscle | junior male handball players | +9% | showed significant increases | #4 |
6-week eccentric isokinetic resistance training | increase | fractional anisotropy of the infraspinatus muscle | junior male handball players | +6% | showed significant increases | #5 |
6-week eccentric isokinetic resistance training | no change | range of motion | junior male handball players | - | did not change | #6 |
Background: Team handball involves a tremendous amount of shoulder motion with high forces during repeated extended external range of motion. This causes shoulder complaints and overuse injuries. While eccentric training for the lower extremity shows preventive effects by improving strength, range of motion and fascicle length, there is a research gap for the shoulder joint and for advanced tissue characterization using diffusion tensor imaging. Objectives: To investigate the effects of 6-week eccentric isokinetic resistance training on strength, flexibility, and fiber architecture characteristics of the external rotators compared to an active control group in junior male handball players. Methods: 15 subjects were randomly assigned to the eccentric training group and 14 subjects to the active control group (conventional preventive training). Primary outcome measures were eccentric and concentric isokinetic strength of the external rotators, range of motion, and muscle fascicle length and fascicle volume. Results: The intervention group, showed significant changes in eccentric strength (+15%). The supraspinatus and infraspinatus muscles showed significant increases in fascicle length (+13% and +8%), and in fractional anisotropy (+9% and +6%), which were significantly different from the control group. Conclusion: Eccentric isokinetic training has a significant effect on the function and macroscopic structure of the shoulder external rotators in male junior handball players. While strength parameters and muscle structure improved, range of motion did not change. This research helps understanding the physiology of muscle and the role of eccentric training on shoulder function and muscle structure. Furthermore, DTI was found to be a promising tool for advanced tissue characterization, and the in vivo derived data can also serve as model input variables and as a possibility to extend existing ex-vivo muscle models. Future research is needed for functional and structural changes following convenient eccentric field exercises.