According to the Fick principle, VO2 max depends on which two factors?

According to the Fick principle, VO2 max depends on which two factors?

• A. Ventilatory efficiency and diffusion capacity
• B. Maximum cardiac output and maximal arteriovenous oxygen difference
• C. Arterial oxygen content and venous oxygen content
• D. Pulmonary diffusion rate and capillary density

Answer: (B)

The rate at which our tissues consume oxygen is set by how much blood the heart can deliver and how much of that oxygen the tissues can extract from that blood. In simple terms, oxygen consumption (VO2) equals cardiac output (the amount of blood pumped per minute) times the arteriovenous oxygen difference (how much oxygen is extracted from that blood as it passes through the muscles). So, VO2 max is achieved when both the maximum blood flow (Qmax) and the maximum amount of O2 that can be extracted (a-vO2 diff max) are at their peaks. The other options mix in factors related to gas exchange or diffusion that influence oxygen delivery or uptake indirectly but do not define VO2 max as described by the Fick principle.