What is the key difference between aerobic and anaerobic exercise?

Aerobic exercise is characterized by its reliance on oxygen to fuel the body’s activities over extended periods. This type of exercise, which includes activities like running, swimming, and cycling, involves the sustained use of large muscle groups and is designed to improve cardiovascular endurance. During aerobic activities, the body uses oxygen to metabolize fat and carbohydrates, which provides the necessary energy for longer-lasting physical exertion.

In contrast, anaerobic exercise focuses on short bursts of high-intensity activity where the body's oxygen demand surpasses the oxygen supply available. This type of exercise typically builds strength and muscle mass, as seen in weightlifting and sprinting. Therefore, the distinction lies in the duration and intensity of the activities, rather than in the purpose or outcomes of the exercises described in the other options.