Which macronutrient is the primary source of energy during high-intensity exercise?

Carbohydrates are indeed the primary source of energy during high-intensity exercise. When engaging in activities that require significant bursts of effort, such as sprinting or heavy weight lifting, the body relies heavily on glycogen stored in muscles and the liver. Glycogen is the stored form of carbohydrates and can be quickly converted into glucose, which is then utilized by the muscles for immediate energy.

During high-intensity exercise, the demand for energy exceeds that which can be supplied by fat oxidation alone, as fat is metabolized at a slower rate and is more suited for lower-intensity, longer-duration activities. While protein can serve as an energy source, particularly during prolonged exercise or caloric restriction, it is not the preferred fuel source during high-intensity efforts. Fiber, on the other hand, primarily plays a role in digestive health rather than providing energy for exercise. Thus, carbohydrates are essential for optimal performance in activities requiring quick, powerful movements.