During prolonged exercise, the body generates energy primarily through aerobic metabolism, which relies on oxygen to convert carbohydrates and fats into adenosine triphosphate (ATP). Initially, stored ATP and creatine phosphate are utilized, but as exercise continues, the body shifts to burning glycogen stores and ultimately fats. If prolonged exercise continues beyond glycogen storage capabilities, muscle protein may also be utilized. This energy production is crucial for maintaining performance and endurance in long-duration activities, emphasizing the importance of proper fueling before and during exercise.