Carbohydrates significantly affect athletic performance as they are the primary fuel source during high-intensity exercise. They are stored as glycogen in muscles and liver, providing quick energy during workouts. Adequate carbohydrate intake is essential for optimizing performance, delaying fatigue, and facilitating recovery. Athletes should focus on consuming complex carbohydrates before and after exercise to replenish glycogen stores and maintain sustained energy levels, ensuring effective performance in activities ranging from endurance sports to high-intensity training.