Glycogen serves as the body's primary form of stored energy and is crucial during exercise. It is primarily stored in the liver and muscles and can be quickly converted to glucose when energy demands rise, such as during physical activity. During exercise, especially high-intensity activities, glycogen is broken down to provide the necessary fuel for muscle contractions. Maintaining optimal glycogen stores through a balanced diet that includes sufficient carbohydrates is essential for athletic performance and recovery, as it aids endurance and delays fatigue during prolonged exercise.