What is the primary source of energy for high-intensity exercise?

Carbohydrates serve as the primary source of energy for high-intensity exercise due to their ability to be rapidly metabolized to produce adenosine triphosphate (ATP), the energy currency of the body. During high-intensity activities, such as sprinting or heavy lifting, the body relies on glucose, which can be derived from the breakdown of carbohydrates either through the bloodstream or stored as glycogen in muscles and the liver. This glucose can be utilized quickly to meet the immediate energy demands of intense physical exertion.

In contrast, while proteins can be used as an energy source, they primarily serve other roles in the body, such as repair and growth of tissues. Fats are also a vital energy source, particularly during lower-intensity exercise, because their metabolism is slower compared to carbohydrates. Vitamins, while essential for various biochemical processes, do not provide energy directly. They support metabolic functions but do not serve as fuel sources for exercise. This makes carbohydrates the most efficient and effective option for high-intensity workouts.