How is oxygen consumption calculated?

Oxygen consumption, often measured as VO2, is a critical component in assessing aerobic capacity and overall cardiovascular fitness. It reflects the amount of oxygen taken up and utilized by the body during physical activity. The correct method to calculate oxygen consumption involves cardiac output, which is the volume of blood the heart pumps per minute, and oxygen extraction, which refers to the difference in oxygen content between arterial and venous blood.

Cardiac output is essential because it determines how much blood is available to deliver oxygen to the tissues. Oxygen extraction indicates how well the tissues are able to use the delivered oxygen. Together, these two measurements provide a comprehensive picture of how efficiently the body can take in, transport, and utilize oxygen during physical exertion.

In contrast, the other options either don't relate directly to the components necessary for calculating oxygen consumption or involve incorrect physiological parameters. For example, heart rate alone does not account for blood volume or how effectively the body extracts oxygen. Similarly, respiratory rate and blood volume do not correlate directly with oxygen consumption, making those options less relevant in this context. Therefore, option B accurately reflects the relationship required to determine oxygen consumption in a physiological setting.