This study was made to answer the question of optimal feeding time before the exercise.
　Forty-eight male Sprague-Daily rats were daily meal-fed on a commercial diet at 20.00-21.00 and 08.00-09.00 hr for 3 weeks.
　At 7 weeks of age, the rats were classified into control groups and 3 exercised groups, namely rats fed with the meal at just before, 3 hours before, and 6 hours before a bout of 3 hours swimming exercise.
　Blood substrate, tissue glycogen content, adipose tissue lipolysis, and tissue lipoprotein lipase activity were measured at two times just before and after the exercise.
　The results obtained were summarized as follows;
　1. In the rats fed with the meal just before the exercise, liver and skeletal muscle glycogen contents at the end of the exercise were lower as compared with those in the rats of the other two groups.
　2. In the rats fed with the meal at 3 hours before the exercise, liver and skeletal muscle glycogen contents at the time just before the exercise were similar to those in the rats fed with the meal just before the exercise. However, those at the end of the exercise were similar to those in the rats fed with the meal at 6 hours before the exercise.
　3. In the rats fed with the meal at 6 hours before the exercise, skeletal muscle glycogen contents at the time just before the exercise were higher as compared with those in the rats of the other two groups. However, those at the end of the exercise were similar to those in the rats fed with the meal at 3 hours before the exercise.
　These results suggest that the feeding just before the exercise is not optimal in rats.

DESCENTE SPORTS SCIENCE Vol.6/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE