Pulse pressure
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Pulse pressure is the change in blood pressure seen during a contraction of the heart. Formally it is the systolic pressure minus the diastolic pressure.
Usually, the resting pulse pressure in healthy adults, sitting position, is about 40 mmHg. The pulse pressure increases with exercise due to increased stroke volume, healthy values being up to pulse pressures of about 100 mmHg, simultaneously as total peripheral resistance drops during exercise. In healthy individuals the pulse pressure will typically return to normal within about 10 minutes.
For most individuals, during exercise, the systolic pressure progressively increases while the diastolic remains about the same. In some very aerobically athletic individuals, the diastolic will progressively fall as the systolic increases. This behavior facilitates a much greater increase in stroke volume and cardiac output at a lower mean blood pressure and enables much greater aerobic capacity and physical performance. The diastolic drop reflects a much greater fall in total peripheral resistance of the muscle arterioles in response to the exercise (a greater proportion of red versus white muscle tissue).
If the usual resting pulse pressure is less than 40 mmHg, the most common reason is an error of measurement. Another, much less frequent, but more important and serious reason is low stroke volume. Thus a low pulse pressure, e.g. 25 mmHg of less may represent a low stroke volume, as in Congestive Heart Failure and/or shock. This is the more likely assessment if the resting heart rate is also relatively rapid, e.g. 100-120 (in normal sinus rhythm), reflecting increased sympathetic nervous system activity attempting to improve stroke volume and cardiac output.
If the usual resting pulse pressure is consistently greater than 40 mmHg, e.g. 60 or 80 mmHg, the most likely basis is stiffness of the major arteries, a leak in the aortic valve, an extra path for the blood to travel from the arteries to the veins, of some combination. (A chronically increased stroke volume is also a technical possibility, but very rare in practice.)