1991 Volume 35 Issue 4 Pages 341-348
The purpose of this study was to investigate the combined effects of dietary composition of pre-exercise meal and feed-timing to liver and muscle glycogen depletion and lypolytic activity during prolonged exercise in rats. Rats were meal-fed twice a day with a normal diet for 3 weeks. They were divided into two groups on the final day of the experiment. One group of the rats were given a high-carbohydrate (H-CHO) diet and the other group high-fat (H-FAT) diet. Then, each dietary group were divided two groups. One group of either dietary groups were loaded a bout of 2-h swimming exercise 3 hr after the meal. Another group of either dietary groups were started exercise 7 hr after the meal. At the end of exercise serum concentration of glucose of that started exercise 3 hr after the meal was higher in H-CHO group than in H-FAT group. However, serum glucose levels in H-CHO group significantly decreased during exercise when started 3 hr after the meal as compared with H-FAT group. Glycogen contents in liver of both dietary groups significantly decreased during exercise. Although liver glycogen contents at the end exercise were sgnificantly higher in H-CHO group that started exercise 3 hr after the meal than in H-FAT group, no significant difference was found between the groups 7 hr after the meal. Furthermore, no significant difference was found on glycogen contents of soleus muscle in both dietary groups at the end of exercise both 3 and 7 hr after the meal. Lipolytic activities in H-FAT group were signjficantly increased during exercise and there were no differences between two cases of the starting time. However these trends were not observed in H-CHO group. From these results, it was suggested that effects of dietary composition of pre-exercise meal on the changes of liver and muscle glycogen depletion and lipolytic activity during prolonged exercise were different according to feed-timing.