A study was conducted to investigate the influence on the shoulder joint of throwing during water polo. One hundred sixty-seven water polo players were interviewed about injuries caused by water polo, and 70 players claimed to have had shoulder pain.
In 21 players, clinical examinations were performed, and in 31 players, assessment of external rotation stability was made. Then three-dimensional analysis of hand-to-hand shoot motion was performed in 7 players.
The results were as follows;
1. The painful phases of the throwing motion were the take-back phase and the acceleration phase, the pain being present at the anterior and lateral portions of the shoulder joint,
2. Assessment of stability revealed that the external rotation displacement on the affected side was significantly larger than that on the control side in the injured players.
3. Analysis of hand-to-hand shoot motion revealed that the external rotation angle in the acceleration phase was significantly larger in non-injured subjects than in the injured.
4. The external rotation angle after ball contact was increased in the injured, but decreased in the non-injured.
5. To prevent injury, it appears important to catch and throw the ball using the upper extremity and rotation of the trunk in a high body position in the water, and to strengthen the muscles of the shoulder.
