During prolonged physical activity, the body primarily uses carbohydrates as a key source of energy. Initially stored in the muscles and liver as glycogen, carbohydrates are broken down to glucose, providing immediate fuel for various intensities of exercise. As the duration extends, the body gradually shifts from relying exclusively on carbohydrates to incorporating fat metabolism. Maintaining adequate carbohydrate supplies before and during activities is crucial for sustained performance, as insufficient glucose can lead to fatigue and decreased endurance. Thus, a balanced carbohydrate intake is vital for effective energy management.