Which macronutrient is primarily used by the body for energy during high-intensity exercise?

The body primarily relies on carbohydrates for energy during high-intensity exercise. During such activities, the demand for quick energy surges, and carbohydrates are broken down into glucose, which is readily accessible for immediate use by the muscles. This process occurs through anaerobic glycolysis, which allows for rapid ATP production to meet the energy needs of intense physical exertion.

In contrast, fats serve as a primary energy source during low to moderate-intensity exercise due to their slower breakdown process. Proteins are generally not used as a primary energy source; rather, they play a crucial role in muscle repair and growth. Vitamins also do not provide energy directly; instead, they support various biochemical processes in the body, including those involved in energy metabolism. Therefore, the highlighting of carbohydrates as the main energy source during high-intensity workouts reflects their crucial role in supporting performance and endurance.