During moderate aerobic exercise, which of the following best describes the relationship between cardiac output, systemic vascular resistance, and mean arterial pressure?

During moderate aerobic exercise, which of the following best describes the relationship between cardiac output, systemic vascular resistance, and mean arterial pressure?

• A. Cardiac output rises; SVR falls; mean arterial pressure increases modestly
• B. Cardiac output decreases; SVR rises; mean arterial pressure falls
• C. Cardiac output rises; SVR rises; mean arterial pressure spikes
• D. Cardiac output remains constant; SVR remains constant; mean arterial pressure remains constant

Answer: (A)

During moderate aerobic exercise, the heart increases its output to meet the higher demand from working muscles, so cardiac output rises as heart rate and stroke volume both go up. At the same time, blood vessels in active muscles dilate to enhance blood flow, driven by local metabolic signals, which lowers systemic vascular resistance. Since mean arterial pressure is closely related to the product of cardiac output and systemic vascular resistance, the boost in output tends to raise MAP, but the fall in resistance offsets much of that rise. The net effect is a modest increase in mean arterial pressure.

During moderate aerobic exercise, the heart increases its output to meet the higher demand from working muscles, so cardiac output rises as heart rate and stroke volume both go up. At the same time, blood vessels in active muscles dilate to enhance blood flow, driven by local metabolic signals, which lowers systemic vascular resistance. Since mean arterial pressure is closely related to the product of cardiac output and systemic vascular resistance, the boost in output tends to raise MAP, but the fall in resistance offsets much of that rise. The net effect is a modest increase in mean arterial pressure.