Mobility impairment, muscle imbalance, muscle weakness, scapular asymmetryand shoulder injury in elite volleyball athletes

Background. The aim of this study was to evaluate the relationship between shoulder mobility, rotator muscles' strength and scapular symmetry, and sho ulder injuries and/or pain in elite volleyball athletes. Methods. An isokinetic shoulder muscle strength test, which was performed a t speeds of 60/sec and 180/sec, and shoulder mobility and scapula lateral s lide tests were conducted bilaterally on 16 subjects, who represented the E ngland elite volleyball players. The subjects also prospectively completed monthly questionnaires during the competition season to report on their sho ulder condition. Results. The results showed that the active range of shoulder internal rota tion and concentric external rotators' strength in the dominant arm were si gnificantly less, than in the non-dominant arms, but the internal rotators were significantly stronger in both concentric and eccentric tests at both testing speeds. Seven of 16 subjects indicated overt shoulder injury or pai n during their training season, nine subjects had shoulder mobility impairm ent, seven had muscle imbalance, 13 had relative muscle weakness and five h ad scapular asymmetry. The association between shoulder muscle strength imb alance (eccentric external < concentric internal) of rotators in the domina nt arm and shoulder injuries was statistically significant (Fisher's exact test, p <0.05). Conclusions. We conclude that rotator muscle strength imbalance may play an important role in shoulder injuries in high-level volleyball players.