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 body needs more oxygen delivery to active muscles, so cardiac output increases to push more blood through the circulation. At the same time, vessels in the working muscles dilate to allow this greater flow, which lowers systemic vascular resistance. Because mean arterial pressure is roughly the product of cardiac output and systemic vascular resistance, the large rise in CO tends to push pressure up, but the fall in SVR counteracts that, so MAP goes up only modestly. This combination—cardiac output increasing, SVR decreasing, and mean arterial pressure rising modestly—best fits the physiological response.

Other patterns, like CO decreasing or SVR increasing, don’t match how the cardiovascular system adapts to exercise, and keeping all three constants would ignore the clear changes in heart performance and vascular tone that occur.