Which physiological process directly raises systolic blood pressure during exercise?

During exercise, the body's demand for oxygen and nutrients increases significantly, which directly leads to a rise in systolic blood pressure. This rise is primarily due to increased cardiac output. Cardiac output is the volume of blood the heart pumps per minute, and it is determined by both heart rate and stroke volume (the amount of blood pumped with each beat).

As physical activity intensifies, the body responds by increasing both the heart rate and the stroke volume to supply blood more efficiently to the working muscles. This heightened activity of the heart causes a greater volume of blood to be ejected into the arteries, thereby elevating blood pressure, specifically systolic pressure, which is the pressure in the arteries during the contraction of the heart.

In contrast, vasodilation of blood vessels would typically lower blood pressure, as the blood vessels widen and allow blood to flow more easily. Lower blood volume would decrease blood pressure, and an overall decreased heart rate would reduce cardiac output and subsequently lower blood pressure. Therefore, the physiological process that directly contributes to the rise in systolic blood pressure during exercise is indeed the increase in cardiac output.