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.

Effect of exercise on glycogen level in muscles and liver in rats.

The effect of exercise of glycogen level in skeletal muscles and liver was studied in Wistar rats. The previously untrained animals were subjected to one-time exercise in form of swimming in water at 32 degrees C for 10, 20 and 30 min. The glycogen level in the muscles (in g per 100 g of tissue) fell down during the first 10 minutes of the exercise by a mean value of 0.45 g. During the following 10 minutes the decrease was smaller amounting on the average to 0.1 g. After 30 min the glycogen level in the muscles was about 0.1 g/100 g of tissue. Respective falls of glycogen level in the liver were on the average 0.99 g and 0.40 g/100 g of tissue. After 30 min of exercise the glycogen level in the liver was 1.2 g/100 g of tissue. The fall of glycogen level in the muscles was similar at all times during exercise in all animals, but in the liver fairly significant differences were observed in the first 10 min between individual groups of rats. Later on during exercise the differences in the liver glycogen falls decreased.