Which of the following is a measure of aerobic fitness?

• A. VO2 max
• B. BMI
• C. Max sprint speed
• D. Flexibility

Answer: (A)

Aerobic fitness is about how well the body can supply and use oxygen during sustained activity. The best measure of this capacity is VO2 max—the maximum rate at which the body can take in and use oxygen during intense exercise, typically shown in ml of oxygen per kilogram of body weight per minute. It reflects the efficiency of the whole oxygen-transport system: how well the heart can pump blood, how effectively the lungs oxygenate it, how well the blood carries it to the muscles, and how efficiently the muscles use that oxygen for energy. A higher VO2 max generally means greater endurance and ability to sustain activity for longer periods.

BMI, on the other hand, is a simple ratio of weight to height and doesn’t tell you anything about how fit the person is. Max sprint speed measures how fast someone can move over a short distance and relies more on anaerobic power and neuromuscular factors than on oxygen uptake. Flexibility concerns the range of motion of joints and soft tissues, not the body’s aerobic energy system. So VO2 max best captures aerobic fitness.