Blood pressure measurements consist of two numbers. The first figure, or systolic pressure, measures the blood pressure while your heart is contracting. The second number, the diastolic pressure, measures the pressure between heartbeats when the heart is relaxed. During vigorous aerobic exercise, systolic blood pressure normally rises, while diastolic pressure changes very little. Abnormal blood pressure responses to a workout, such as a large increase in diastolic pressure or an exaggerated spike in systolic pressure, may indicate that you are at risk for developing high blood pressure or cardiovascular disease.
Two factors combine to determine your blood pressure: how much blood your heart pumps per minute, called cardiac output, and how much your arteries resist blood flow, termed peripheral resistance. When arteries narrow, peripheral resistance rises. When they widen, peripheral resistance drops. More cardiac output and greater peripheral resistance result in higher blood pressure. Healthy blood pressure should be less than 120/80mm Hg.
Blood Pressure During Exercise
During vigorous exercise, your systolic blood pressure rises because your heart must work harder to pump more blood with each contraction to keep your muscles supplied with oxygen. The more strenuous the exercise, the greater the rise in systolic pressure. During a very vigorous workout, systolic blood pressure in a healthy athlete may rise to as high as 200 mm Hg. Normally, however, diastolic blood pressure changes very little, if at all. In a young, healthy person, diastolic blood pressure typically rises by no more than a few mm Hg, even during a strenuous workout. That's because the blood vessels in your working muscles widen, decreasing peripheral resistance.
Exaggerated Blood Pressure Response
A 2002 study published in the journal "Hypertension" found that an exaggerated blood pressure response to exercise may indicate a greater risk of future hypertension. The study tracked 726 men with normal blood pressure for almost five years. Researchers found that men with the greatest rise in systolic and diastolic pressure during exercise at the start of the study were more likely to have developed hypertension by the end of the study than those with a normal blood pressure response.
In a study of more than 2,000 male and female participants in the landmark Framingham Heart Study, published in the journal "Circulation" in 2012, researchers measured blood pressure response during exercise testing on a treadmill. They found that individuals with stiffer arteries -- which give greater resistance -- were more likely to experience higher increases in both systolic and diastolic pressure during vigorous exercise.