This study was conducted to examine the effects of different types of swimming on vision, including contrast sensitivity, depth perception, static visual acuity, number of eyeblinks, and pain scale. Six college water-polo players swam (A) at a water flow rate of 0 m·sec^-1 with floating, (B) at 0.83±0.04 m·sec^-1 with floating, (C) at 1.09±0.05 m·sec^-1 with floating, (D) at 0.83±0.04 m·sec^-1 doing the front crawl (50%VO₂max), and (E) at 1.09±0.05 m·sec^-1 doing the front crawl (80%VO₂max) for 15 min on a swimmill. To avoid the effect by chlorine, the free radical residual chlorine concentration was fixed at 0 ppm in the swimmill.
We found no significant differences in vision before and after A. On the other hand, contrast sensitivity during the test decreased significantly in C and E (p<0.05) . Depth perception and number of eyeblinks increased significantly in C and E (p<0.05) . Subjects had a high pain scale in C and E (p<0.01) . Thus it seems that water flow may disturb of vision. We conclude that it is impor. tant for swimmers to prevent impairment of vision.

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.