They are the way the body stores carbohydrates, which then will be those who will use an athlete when you need energy and that are a major source of energy during the first hour of activity.
With regard to energy for physical activity, duration and intensity of activity affect the type and amount of energy consumed.
For aerobic training, 70% of the energy comes from glycogen, while the rest comes from fat.
For sports that require short bursts of intense energy, such as tennis, these carbohydrates are the main source of energy.
Endurance sports, which require a constant intensity, also use the muscle glycogen. After 90 to 120 minutes of exercise, glycogen reserves plummet, so then the body uses fats.
Adequate intake
Based on a diet of 2,000 calories a day, 275 grams of carbohydrates is normal.
Most people have a schedule in which with difficulty can include new activities, which usually is used as an excuse not to exercise, despite knowing that by maintaining a moderate level of activity can improve health and prevent aging.