Pre-exercise rather than post-exercise intake of a large meal enhances liver glycogen sparing during endurance exercise in rats

We investigated the effects of feeding a large meal to female rats (n = 66) just before or just after voluntary wheel running on energy metabolism during a final endurance exercise test. The rats were divided into three groups;one fed a large meal just before exercise (BE), one fed a large meal just after exercise (AE), and one fed ad libitum (AD). The rats were allowed to run voluntarily from 20:00 to 07:00 h. The BE group were given a large meal (more than 12 g) between 19:00 and 20:00 h and a small meal (3 g) between 07:00 and 08:00 h. The AE group were given a large meal (more than 12 g) between 07:00 and 08:00 h and a small meal (3 g) between 19:00 and 20:00 h. After 4 weeks, 6 rats in each group were sacrificed at 22:00 h, and 12 rats in each group were sacri ficed after 30 min starting from 22:00 h at 15 m/min (n = 6) or 35 m/min (n = 6) on a rodent treadmill (0 degrees grade). Four rats in each group were sacrificed after 30 min starting from 22:00 h at rest on the treadmill as a control. The plasma free fatty acid (FFA) and glycerol concentrations increased significantly during low-speed exercise in the AD group, and during higher-speed exercise in all groups. The liver glycogen concentration was significantly greater in the AE group than in the other groups at rest, and decreased significantly during exercise at both speeds in the AD group, but not in the BE and AE groups. The gastrocnemius muscle glycogen concentration was decreased significantly during exercise at both speeds in the AD group, and at high speed in the BE and AE groups. These results indicate that intake of a large meal just after exercise can store a high level of liver glycogen at the beginning of exercise than ad libitum feeding or large meal intake just before exercise, and expend plasma FFA in muscle during exercise compared with ad libitum feeding. This suggests that large meal intake just after exercise contributes to improvement of metabolic capacity in endurance exercise with enhanced liver glycogen sparing.