Insulin increases thermogenesis in rat skeletal muscle following exercise

Insulin increased O2 consumption in isolated perfused rat muscle for upward of 2 h after a treadmill run. Insulin did not increase O2 consumption in nonexercised rats, nor did prior exercise increase O2 consumption in the absence of added insulin. The stimulation of glycogen synthesis by insulin was also enhanced in muscle of previously exercised rats. The additional energy required for this was not sufficient to account for the increase in O2 consumption, however. The results indicate that insulin increases thermogenesis in skeletal muscle after exercise. They also raise the possibility that in intact organisms the thermogenic effect of foods that increase insulin secretion could be increased by prior exercise.