Are My Blood Pressure and Heart Rate Changing Normally During Exercise?
Daniel E. Forman, M.D.

Harvard Health Letters

Q. Sometimes I take a walk while wearing my blood pressure cuff. For the first few minutes, as I walk at a modest pace, my systolic blood pressure rises from 115 to 130 or so, while my heart rate hardly changes from its usual 60-something beats per minute. But when I start walking faster, my systolic pressure stays steady or sometimes goes down a bit, while my heart rate increases to 110. Is this a normal pattern? Can you explain what's going on?

A. When the average healthy person is sitting or walking at a normal pace, the heart, lungs, and blood vessels easily supply the body with all the oxygenated blood it needs. Start walking faster, or running, and the extra oxygen demanded by the leg muscles causes predictable changes in the circulatory system: the heart pumps faster and harder as it works to supply more blood to the active muscle; changes in the muscle tone of blood vessels redirect blood away from the digestive system and toward working muscle.

These changes in heart rate, pumping intensity, and vascular tone usually cause a modest increase in systolic blood pressure. This is the pressure recorded as the heart contracts during systole (SIS-tuh-lee). It is represented by the upper number of a blood pressure reading.

In people who rarely exercise, heart rate and systolic blood pressure shoot up almost immediately with even a small increase in activity. This is mostly because the heart is not accustomed to pumping large amounts of blood, so it can supply more blood to the muscles only by pumping at a faster heart rate. Yet even though their heart rates tend to speed up quickly with light exercise, their peak heart rates tend to be lower when exercising hard than in folks who exercise regularly. Such blunted peak heart rates (also called chronotropic incompetence) tend to be associated with feeling less energy and vigor, since the heart can't provide as much blood as the body needs.

A different pattern occurs in adults who exercise a lot. Over time, their hearts develop ways to deliver more blood with each beat through better filling and more vigorous contractions. In regularly active people, the heart rate tends to rise more slowly in response to light exercise than in people who don't exercise much. But their peak heart rates can and do climb to relatively higher levels as they move into strenuous activity.

Systolic blood pressure should always increase with exercise. At some point, above 220, the risk of cardiovascular trouble increases.

Part of my work involves monitoring and evaluating people doing exercise stress tests on a treadmill. Heart rate and blood pressure are two of the many things I watch. There are several changes that can occur during exercise that are pertinent to your question:

In some people who are not athletes, the heart rate doesn't go up as much as it should as they walk faster on the treadmill. While this can be a matter of clinical concern, it's also a common side effect of medications, particularly beta blockers.

In other people, blood pressure doesn't rise as it should. This may be an indication the heart is not pumping healthfully or that blood vessels are not shifting blood appropriately. Sometimes this can be chalked up to the fact that the person did not eat enough recently or that his or her normal blood pressure medications are interfering with the exercise testing responses.

Although there are general physiologic changes that occur with exercise, each one of us has a unique response. I can't say anything about your specific pattern of changes in heart rate and blood pressure. But I can say that if you are worried about the way your heart and blood pressure respond to exercise, ask your doctor if an exercise test is appropriate for you.

Daniel E. Forman, M.D., Director, Exercise Testing Laboratory, Brigham and Women's Hospital, Associate Professor of Medicine, Harvard Medical School

Twitter: @ihavenet

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