What is the primary source of energy during prolonged exercise beyond 2 minutes?

During prolonged exercise exceeding 2 minutes, the body primarily relies on aerobic processes to meet energy demands. Aerobic glycolysis becomes a primary source of energy because it efficiently utilizes oxygen to convert carbohydrates into glucose, subsequently producing ATP, the energy currency of our cells. This process is sustainable and can provide energy for extended periods, especially during steady-state exercise like running or cycling.

While anaerobic glycolysis and the ATP-CP system contribute to energy production, they are predominantly used in shorter bursts of high-intensity exercise. The ATP-CP system fuels the first few seconds of intense activity, quickly replenishing ATP without the need for oxygen but depleting rapidly. Anaerobic glycolysis kicks in for a bit longer, typically under high-intensity conditions when oxygen availability is low, but it can only sustain activity for a limited time and produces lactate, which can lead to fatigue.

Fatty acid oxidation, although an important source of energy, primarily becomes significant during lower-intensity, prolonged exercise after the initial few minutes and when the body's carbohydrate stores decrease. However, it is less efficient compared to aerobic glycolysis for moderate to high-intensity exercise. Thus, during prolonged exercise beyond 2 minutes, aerobic glycolysis is the main energy pathway supporting