Which of the following does NOT normally increase during an aerobic exercise session?

Which of the following does NOT normally increase during an aerobic exercise session?

• A. End-diastolic volume
• B. Cardiac contractility
• C. Cardiac output
• D. Diastolic blood pressure

Answer: (D)

During aerobic exercise the body's demand for oxygen rises, so the heart and vessels adapt to deliver more blood to working muscles. End-diastolic volume tends to increase because venous return is enhanced by the muscle pump and breathing movements, which preload the ventricles and allow a greater stroke volume through the Frank-Starling mechanism. Cardiac contractility also increases due to sympathetic stimulation, making each beat eject more blood. As a result, cardiac output rises since both heart rate and stroke volume go up. Diastolic blood pressure, however, does not normally increase; it usually stays about the same as at rest or may decrease slightly because of vasodilation in the active muscles that lowers peripheral resistance, even while cardiac output is higher. So the variable that does not normally increase is diastolic blood pressure.

During aerobic exercise the body's demand for oxygen rises, so the heart and vessels adapt to deliver more blood to working muscles. End-diastolic volume tends to increase because venous return is enhanced by the muscle pump and breathing movements, which preload the ventricles and allow a greater stroke volume through the Frank-Starling mechanism. Cardiac contractility also increases due to sympathetic stimulation, making each beat eject more blood. As a result, cardiac output rises since both heart rate and stroke volume go up. Diastolic blood pressure, however, does not normally increase; it usually stays about the same as at rest or may decrease slightly because of vasodilation in the active muscles that lowers peripheral resistance, even while cardiac output is higher. So the variable that does not normally increase is diastolic blood pressure.