During which type of exercise would your muscles primarily use oxygen for energy?

The correct choice is associated with exercises that are performed at a moderate intensity over a prolonged period of time. During aerobic exercise, the body relies on oxygen to produce energy through the process of aerobic metabolism. Activities such as running, swimming, and cycling exemplify this type of exercise, where the heart and lungs work efficiently to deliver oxygen to the muscles, enabling sustained effort.

In contrast to anaerobic exercise, which relies on energy sources stored in the muscles and does not require oxygen, aerobic exercise emphasizes continuous, rhythmic movement, promoting cardiovascular health and improving endurance. Muscular endurance, while related to how long a muscle can perform a specific movement, can involve both aerobic and anaerobic pathways but primarily benefits from aerobic conditioning. Flexibility training focuses on the range of motion in joints and does not primarily engage energy systems dependent on oxygen consumption. Therefore, aerobic exercise stands out as the type of exercise where muscles predominantly utilize oxygen for energy.