Effect of time of carbohydrate ingestion on muscle glycogen resynthesis after exhaustive exercise in rats.

We studied the optimal time of carbohydrate ingestion required to restore muscle glycogen storage after exhaustive exercise in rats. The animals were divided into 4 groups (IN0, IN30, IN60 and IN120), each receiving 30% glucose solution (30 g/kg body weight) through a stomach tube 0, 30, 60 or 120 minutes after exercise. Six hours after administration of glucose, the glycogen concentration in the m. extensor digitorum longus returned to the baseline in the IN0 group, while reaching only 77%, 80% and 73% of the baseline in the IN30, IN60 and IN120 groups, respectively. There was a significant difference in this variable between the IN0 group and any of the three other groups. On the other hand, the glycogen concentration in the m. soleus returned to the baseline in all groups with no difference. These findings suggest that muscle glycogen may be most efficiently resynthesized if carbohydrate is given immediately after exercise, and that muscle glycogen resynthesis may vary with the type of muscle.