What distinguishes aerobic exercise from anaerobic exercise?

Aerobic exercise is characterized by its dependence on oxygen for the production of energy. During aerobic activities, such as running, swimming, or cycling, the body utilizes oxygen to convert carbohydrates and fats into energy, allowing for sustained physical activity over extended periods. This metabolic process supports prolonged efforts and is fundamental in activities that keep the heart rate elevated for longer durations.

The other options present distinctions that do not accurately describe the nature of aerobic exercise. For instance, the suggestion that aerobic exercise requires no oxygen is fundamentally incorrect, as the term "aerobic" itself implies the use of oxygen. Furthermore, aerobic exercise typically lasts longer, contradicting the notion of being shorter in duration. Lastly, while aerobic workouts may not primarily focus on muscle building compared to anaerobic movements, they still contribute to overall muscle endurance.