Mobility impairment, muscle imbalance, muscle weakness, scapular asymmetry and shoulder injury in elite volleyball athletes.

Abstract

The aim of this study was to evaluate the relationship between shoulder mobility, rotator muscles' strength and scapular symmetry, and shoulder injuries and/or pain in elite volleyball athletes. An isokinetic shoulder muscle strength test, which was performed at speeds of 60/sec and 180/sec, and shoulder mobility and scapula lateral slide tests were conducted bilaterally on 16 subjects, who represented the England elite volleyball players. The subjects also prospectively completed monthly questionnaires during the competition season to report on their shoulder condition. The results showed that the active range of shoulder internal rotation and concentric external rotators' strength in the dominant arm were significantly 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 pain during their training season, nine subjects had shoulder mobility impairment, seven had muscle imbalance, 13 had relative muscle weakness and five had scapular asymmetry. The association between shoulder muscle strength imbalance (eccentric external < concentric internal) of rotators in the dominant arm and shoulder injuries was statistically significant (Fisher's exact test, p<0.05). We conclude that rotator muscle strength imbalance may play an important role in shoulder injuries in high-level volleyball players.