Answer: Carbohydrates are one of the most important sources of energy for the living organisms. They serve as efficient energy fuels for the athletes who require energy for vigorous muscle contractions during their training.
Atheletes require lots of complex carbohydrates ( like starch) during training because the already stored form ( glycogen in liver and muscles) is broken down into simple sugar that is glucose, which is metabolized to fulfill the energy requirements. They allow to compete for longer times and do not cause fatigue in athletes.
Therefore, lots of complex carbohydrates are required in their diets.