The primary source of energy during high-intensity exercise is adenosine triphosphate (ATP) and carbohydrates. During short bursts of intense activity, the body relies heavily on stored glycogen in the muscles for quick energy release. The stored ATP provides immediate energy for muscle contractions, while carbohydrates supply a more substantial amount of energy as the intensity continues. Understanding these energy sources helps in optimizing performance and guiding nutritional strategies before and after workouts to ensure sufficient fueling for both high-intensity and prolonged activities.