What does aerobic capacity measure?

Aerobic capacity specifically measures how efficiently the heart and lungs work together to transport oxygen throughout the body during physical activity. This capacity is indicative of an individual's cardiovascular fitness, which is crucial for performing sustained exercise activities that rely on oxygen as a primary energy source.

When aerobic capacity is high, a person's heart can pump more blood with each beat, and their lungs are better at transferring oxygen from the air into the bloodstream. This means that the muscles can receive more oxygen, leading to improved endurance and performance during exercise.

In contrast, the other options do not accurately define aerobic capacity. The first option refers to a specific fuel usage during exercise, while the third describes a physiological parameter related to heart function rather than aerobic capacity itself. The fourth option relates to oxygen storage at the muscle level, which is not the primary focus of aerobic capacity measurement. Therefore, the correct answer emphasizes the overall efficiency of the cardiovascular and respiratory systems in delivering oxygen.