Which macronutrient is primarily responsible for energy during prolonged aerobic exercises?

The correct response highlights that carbohydrates are the primary macronutrient utilized for energy during prolonged aerobic exercises. During aerobic activities, such as long-distance running or cycling, the body relies on a steady supply of energy, which is most efficiently provided by carbohydrates. When carbohydrates are consumed, they are stored in the muscles and liver as glycogen. During prolonged exercise, these glycogen stores are broken down into glucose, which is then used to produce ATP (adenosine triphosphate), the energy currency of the cell.

While fats are also a significant source of energy during longer-duration activities, especially as exercise continues and glycogen stores deplete, the utilization of carbohydrates remains predominant in the early stages of prolonged aerobic exercise. Proteins are mainly used for muscle repair and growth rather than as a primary energy source during exercise. Vitamins do not serve as direct energy sources; instead, they play crucial roles in metabolic processes that support overall energy production but are not a macronutrient themselves.