Which energy system does the body predominantly utilize during marathon running?

During marathon running, the body predominantly utilizes the aerobic energy system. This energy system is most efficient for endurance activities that last for extended periods, such as a marathon. The aerobic system relies on oxygen to break down carbohydrates and fats to produce energy (ATP) over a sustained duration. This system supports prolonged physical activity by providing a steady and sufficient energy supply, allowing the athlete to maintain a relatively consistent pace throughout the race.

In contrast to this, other energy systems have distinct roles. The anaerobic energy system, for example, operates in the absence of oxygen and is primarily engaged during short bursts of high-intensity activity, making it less applicable for marathon distances. Similarly, the phosphagen system, which is utilized for immediate energy demands during very short and intense efforts, quickly depletes and does not support the continuous output required for an endurance event like a marathon. The lactate system, while it contributes to energy production during higher intensity efforts, is also not sustainable for the duration of a marathon as it primarily supports activities that last from about 30 seconds to 2 minutes.

Thus, the choice of the aerobic energy system as the predominant energy source for marathon running is supported by its capacity to generate energy efficiently in an oxygen-rich environment, allowing athletes