Which nutrient is primarily responsible for energy production during prolonged exercise?

Carbohydrates are the primary nutrient responsible for energy production during prolonged exercise. When engaging in activities that require sustained energy, such as running or cycling, the body relies heavily on carbohydrates, as they can be rapidly converted into glucose, which is then used to generate ATP (adenosine triphosphate) — the energy currency of cells.

During prolonged efforts, especially at moderate to high intensities, the body can access glycogen stores in the muscles and liver, allowing for a steady supply of glucose. While fats can also serve as an energy source, their metabolic process is slower and less efficient compared to carbohydrates when rapid energy is needed. Proteins primarily serve the body for repair and growth rather than energy during exercise, and vitamins do not provide energy directly; instead, they play supporting roles in metabolic processes. Thus, carbohydrates stand out as the most effective and immediate source of energy during prolonged physical activity.