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How Does Exercise Affect Insulin and Blood Glucose Levels?
During exercise, to maintain a constant blood glucose level, the blood concentration of insulin drops to counter the “insulin-like” effect of muscle contraction.
Thus the working muscle can take in glucose even though little insulin is present. Another hormone from the pancreas, glucagon, stimulates the liver to release glucose to provide fuel for the muscles.
The pancreas secretes two hormones, insulin and glucagon, to help maintain blood glucose levels. During rest, when blood glucose levels rise after a meal, insulin is secreted to help move the glucose into the body cells. Receptors on the body cells require that insulin be present before glucose can enter. On the other hand, when blood glucose levels drop, glucagon is secreted to increase blood glucose levels by stimulating the breakdown of liver glycogen (i.e., stored carbohydrate).
During exercise, blood insulin levels drop, while blood glucagon levels increase. These changes take place to counterbalance the insulin-like effect of muscle contraction. As the muscles contract during exercise, they do not require much insulin to transport glucose into the working cells. The exercising muscle may increase the uptake of glucose 7-to 20-fold during the first 30 to 40 minutes, depending on the intensity.
In addition, the insulin receptors become more “sensitive” to the lower amount of insulin present during exercise. This improvement in insulin receptor sensitivity can last for many hours after the exercise bout is over, even for as long as two days if the exercise was of long duration and high intensity.