A marathon runner frequently hits the wall becoming exhauste

A marathon runner frequently \"hits the wall\" (becoming exhausted) when they run out of glycogen. To combat this, one runner decided to start bringing a small amount of food with him and chose to bring something with a lot of calories in it: some beef jerky which contains quite a bit of protein and fat. If eaten during the race, will this snack be likely to prevent the runner from \"hitting the wall\"? Explain your reasoning.

Solution

During a marathon, the body uses carbohydrates and fats to provide energy. During the first hour, most of the energy comes from the glycogen stored in your muscles. After an hour the muscles begin to draw their fuel from blood sugar which is supplied by glycogen stored in your liver as wells as from their own stores.

When the glycogen is depleted, the blood sugar level falls and you are unable to carry on exercising. The low blood sugar induces a feeling of tiredness and lightheadedness. So replenishing your blood sugar while you are exercising, you will not deplete your liver glycogen stores so rapidly, with the result that can carry on for longer before you hit the wall.