Which nutrient primarily fuels the body during high-intensity exercise?

Carbohydrates are the primary nutrient that fuels the body during high-intensity exercise. This is because carbohydrates are broken down into glucose, which is the preferred energy source for quick, explosive movements that often occur during activities such as sprinting or heavy lifting. During high-intensity activities, the body engages in anaerobic metabolism, which relies heavily on carbohydrates to provide the ATP (adenosine triphosphate) needed for immediate energy.

In contrast, while fats are a significant energy source during lower-intensity activities or prolonged exercise, they are not as readily converted to energy for high-intensity efforts. Protein serves a more supportive role in energy metabolism and is primarily utilized for muscle repair and recovery rather than as a primary fuel source during high-intensity work. Finally, while water is crucial for overall performance and hydration, it does not provide energy itself and thus cannot function as a fuel source. Therefore, carbohydrates are essential for sustaining energy levels and optimal performance during high-intensity workouts.