What type of exercise primarily uses aerobic energy systems?

The choice of marathon running is correct because it primarily relies on the aerobic energy system. During long-duration activities, such as marathon running, the body uses oxygen to help produce energy over an extended period. This type of exercise involves sustained, moderate-intensity effort that allows cardiovascular efficiency to take over, enabling the body to utilize fat and carbohydrates as fuel sources through oxidative metabolism.

In contrast, short sprints and weight lifting typically involve anaerobic energy systems, which do not rely on oxygen and instead depend on other energy substrates for quick bursts of effort. Resistance training also tends to focus on short, high-intensity movements, emphasizing muscle strength and power rather than endurance. Therefore, marathon running is the primary activity that illustrates the significant utilization of the aerobic energy system during prolonged exercise.