Carbohydrates or sugars are organic compounds consisting of carbon, hydrogen, oxygen. Carbohydrates are metabolized in the body to glycogen and glucose, which are the energy source.
If physical activity are lacking of adequate reserves of sugar, the body uses fats and proteins, especially those muscles, to produce energy.
Carbohydrates of the diet should provide about 60% of the energy needs. A diet low in fat and high in complex carbohydrates during exercise increases muscle glycogen stores.
Endurance athletes should increase the content of complex carbohydrates in the diet (up to 70% of total calories) and minimize the exercise in the 2-3 days before the race.
In a recent study, young healthy volunteers with a diet high in fat and protein showed a content of muscle glycogen and results significantly lower than those obtained for 3 days with a diet high in complex carbohydrates.