Which macronutrient is the main source of energy for endurance sports?

Carbohydrates are recognized as the primary source of energy for endurance sports due to their efficient conversion into glucose, which is the body's preferred fuel source during prolonged periods of exercise. When engaging in activities such as running, cycling, or swimming for an extended duration, the body relies heavily on glycogen stores—carbohydrates that are stored in the muscles and liver.

During endurance events, especially those lasting longer than 90 minutes, the body taps into these glycogen reserves to maintain energy levels and sustain performance. This is crucial because, while fats can also be utilized as an energy source, they do not provide energy as quickly as carbohydrates. Additionally, the need for quick energy during endurance activities makes carbohydrates the most efficient macronutrient. On the other hand, proteins primarily support muscle repair and growth rather than serving as a primary energy source, and vitamins, while essential for various bodily functions, do not provide energy. Therefore, carbohydrates stand out as the main macronutrient fueling endurance sports.