The liver converts carbohydrates into glycogen. Glycogen then goes to the muscles and is stored there. It “burns” quickly and gives the body fast energy. Although this is the basic energy for sprinters, so you should pay attention to the lack of glycogen. It is important to say that marathon runners use it and consume fat.
Glycogen is a fuel
Fat reserves of runners are not a problem. But glycogen reserves are because they cannot be available as long as fat reserves. On average, a runner can store the equivalent of 8 MJ or 2000 kcal of glycogen in the body. Which is enough for about 30 km of running. Of course, this value is not constant for all runners, for some it is less than 30 km. Many marathoners say running after that limit becomes very difficult.
When glycogen drops to a minimum, the body begins to burn fat. Which then provides the necessary energy, but this fat-burning is not as continuous as the burning of glycogen. When this happens, the marathon runner will feel very tired. This phenomenon is usually called the marathon wall. Because it has the impression that the runner hit a wall – suddenly lost strength and slowed down.
The task of training and nutrition for a marathon race is to keep glycogen stores as high as possible so that the “wall” is not so dramatic. Avoiding or disposing of the “wall” can be achieved by using a higher percentage of the energy obtained by burning fat during the early phase of the race, which leads to glycogen savings.
In order for a runner to start consuming fast energy from glycogen, he must run with as high a pulse as possible. Therefore in the higher aerobic zone, and at times in the anaerobic zone. Then carbohydrate/glycogen metabolism prevails over fat metabolism and energy is expended quickly. If you do the opposite – slow down. Fat consumption increases and the use of glycogen decreases by that much, which then lasts longer. Therefore, marathoners, slow down!
Food on the road
There is another way to minimize the effects of the “wall”. By using energy gels that are based on simple sugars (dextrose) that are digested very quickly and resorbed into the blood. Giving the much-needed glycogen to the body.
Generally, these gels are used for 45 to 60 minutes during the race. And they are drunk with the appropriate amount of water. Gels usually contain sodium, and some gels contain caffeine. Some runners use a solution of dextrose in water or some isotonic drinks sweetened with dextrose instead of gel. Dextrose is a simple sugar (D-glucose, grape sugar) that is not digested but is directly resorbed into the bloodstream and provides energy for the muscles.
After the race, you should eat food (and drink) rich in carbohydrates as soon as possible in order to prevent glycogen deficiency, and you should also add proteins (meat, soy…) to speed up the healing of leg muscles. Intake of vitamin C in any form is also implied (it is a good antioxidant). Rest and recovery are necessary after a lot of effort. Only when you recover well, slowly start training again.