Which nutrient is primarily responsible for energy during prolonged exercise?

The primary nutrient responsible for energy during prolonged exercise is carbohydrates. During extended physical activity, especially at moderate to high intensities, the body relies on carbohydrates as its main energy source. This is because carbohydrates are converted more quickly into glucose, which is utilized by the muscles for immediate energy production.

As exercise duration extends, the body initially uses glycogen stores in the muscles and liver, which are made up of carbohydrates. While fats also provide energy during prolonged exercise, particularly in lower-intensity activities, they are metabolized more slowly than carbohydrates. This slower process makes carbohydrates the preferred source during sustained efforts, as they can help maintain performance and prevent fatigue more effectively.

Proteins are generally not a primary energy source during exercise; they serve more crucial roles in muscle repair and recovery after workouts. Vitamins, while essential for various metabolic processes, do not provide direct energy. Therefore, carbohydrates are indeed recognized as the most significant source of energy during prolonged exercise activities.