Functional Evaluation of the Shoulder Joint of Volleyball Players

Abstract

Functional disorders of shoulder joints frequently occur in sports activities, especially in baseball and volleyball. With the aim of examining the characteristics of functional disorders of shoulder joint muscle caused by hitting a ball among volleyball players, muscle strength of shoulder joint in external and internal rotations were measured in 7 subjects with a shoulder joint pain and 5 healthy controls. Functional test of shoulder joint was also conducted in all subjects. Compared with healthy controls, subjects with the pain showed lower muscle peak torque in external rotation, and smaller ratio of internal to external rotations. The subjects exhibited smaller repetition speed of raising and lowering of upper extremity, and lower endurance of abdominal and joint muscles in external rotation. The results suggest that functional disorder of shoulder joint muscle of volleyball players is characterized by a decrease of muscle strength and endurance in external rotation, especially of infraspinatus muscle, which may be caused by overusing shoulders in hitting a ball. The decrease in endurance of abdominal muscle of the subjects suggests that a coordinative stability of scapulohumeral joint-scapula-trunk may play an important role in the prevention of shoulder joint disorders.