What does an increasing a-vO2 difference during exercise indicate?

What does an increasing a-vO2 difference during exercise indicate?

• A. Decreased oxygen extraction
• B. Greater tissue oxygen extraction and utilization
• C. Reduced metabolic demand
• D. Lower cardiac output

Answer: (B)

During exercise, exercising muscles require more oxygen to meet the higher energy demands. The a-vO2 difference tells us how much oxygen is removed from the arterial blood as it passes through the tissues. If this difference increases, it means tissues are extracting more oxygen from each unit of blood and using it more, i.e., greater tissue oxygen extraction and utilization to support the work being done. The other ideas don’t fit as well because a smaller or unchanged difference would suggest less extraction, and reduced metabolic demand would lower the need for oxygen extraction. Cardiac output can rise to deliver more oxygen, but the increasing a-vO2 difference specifically reflects increased extraction by the tissues.

During exercise, exercising muscles require more oxygen to meet the higher energy demands. The a-vO2 difference tells us how much oxygen is removed from the arterial blood as it passes through the tissues. If this difference increases, it means tissues are extracting more oxygen from each unit of blood and using it more, i.e., greater tissue oxygen extraction and utilization to support the work being done. The other ideas don’t fit as well because a smaller or unchanged difference would suggest less extraction, and reduced metabolic demand would lower the need for oxygen extraction. Cardiac output can rise to deliver more oxygen, but the increasing a-vO2 difference specifically reflects increased extraction by the tissues.