Exercise studies were performed on six intact and seven pancreatectomized, unanesthetized dogs to examine the conditions under which exercise decreases the concentration of glucose in blood.
No major change in blood glucose concentration was demonstrated during exercise experiments on normoglycemic intact dogs. In the pancreatectomized dogs, the blood glucose concentration curves during exercise followed either one of two patterns: Some rose with exercise and some fell. In dogs with baseline blood glucose concentrations less than 400 mg. per 100 ml., a sustained decline in blood glucose occurred with exercise, while in those dogs with an initial level greater than 400, a rise occurred.
No effect of exercise was evident in a pancreatectomized dog with blood glucose concentration near the normal range during continuous infusion of insulin. Exercise produced a decrease in blood glucose concentration in an intact dog with hyperglycemia induced by glucose infusion, but this dog's blood glucose level increased during rest periods following exercise.