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

The main source of energy for high-intensity exercise is carbohydrates. During such activities, the body's demand for energy increases rapidly, and carbohydrates can be broken down more quickly than fats or proteins to provide the necessary energy. This process occurs primarily through anaerobic metabolism, where glucose is utilized to produce adenosine triphosphate (ATP), the energy currency of the cells.

Carbohydrates are stored in the muscles and liver as glycogen and can be mobilized rapidly to meet energy demands during short bursts of intense physical activity. This makes them the preferred energy source for high-intensity efforts, such as sprinting, weightlifting, or other anaerobic exercises. In contrast, fats and proteins are not utilized as efficiently for immediate high-energy output; fats, for example, are more suited for lower intensity, longer-duration activities due to their slower oxidation process, while proteins are primarily involved in muscle repair and growth rather than providing energy during exercise.