Describe how the intensity of exercise affects glycogen utilization.

Question

What will be an ideal response?

Answer 1

Glycogen is broken down to glucose, which can be metabolized by both the anaerobic and aerobic pathways. Liver glycogen is used to maintain blood glucose levels, whereas muscle glycogen supplies the glucose to the working muscle. Glycogen is, in fact, the primary source of glucose for ATP production in muscle cells during fairly intense activities that last for less than about 2 hours.

In short events (e.g., less than 30 minutes or so), muscles rely primarily on muscle glycogen stores for carbohydrate fuel. Muscles do not take up much blood glucose during short-term exercise because the action of insulin, which increases glucose uptake by muscles, is blunted by other hormones, such as epinephrine and glucagon during exercise.

As exercise time increases, muscle glycogen stores decline and the muscles begin to take up blood glucose to use as an energy source. The depletion of glycogen in the muscles contributes to fatigue, whereas the depletion of glycogen in the liver leads to a fall in blood glucose.