The function of glycogen in the body during strenuous activity is to serve as a crucial source of stored energy. Glycogen is primarily stored in the muscles and liver and can be rapidly mobilized to provide energy during prolonged or high-intensity activities. When engaging in exercise, the body breaks down glycogen into glucose, which is then utilized by muscles for fuel. Maintaining adequate glycogen stores is vital for sustaining energy levels during workouts, delaying fatigue, and enhancing overall athletic performance.