Glycogen resynthesis in the rat muscle and liver after physical exercise.

Glycogen resynthesis was studied in muscles and liver of Wistar rats after a single bout of physical exercise, which included 30 min of enforced swimming in water at 32 degrees C. The experiment was carried out on untrained rats which rested after the exercise from 30 min to 24 h, receiving food ad libitum. During the postexercise restitution a rise was observed in the glycogen content of both tissues. This rise was more rapid in the muscles than in the liver. During the first 9 hours of rest the muscle glycogen content reached 92.6% of the initial value, and after 24 hours it exceeded this value by 20%. On the other hand, the resynthesis of hepatic glycogen was 67% of the initial value after 9 hours, and after 24 hours the liver glycogen content reached only 76.5% of this value. It has been pointed out also that the restitution of glycogen in the muscles occurs in two steps of the intensive increase, while in the liver it is more steady.