Johns Hopkins Medicine Show
So-called "exercise hypertension," an abnormally high spike in blood pressure experienced by generally healthy people during a workout, is a known risk factor for permanent and serious high blood pressure at rest. But who gets it, and why, has been largely unknown. Now, Johns Hopkins scientists say they have reason to believe that the problem is rooted in the failure of cells that line the blood vessels to allow the arteries to expand to accommodate increased blood flow during exertion. "Our study shows that this impaired ability of the endothelial cells, which control large blood vessel relaxation, is a potential cause of exercise hypertension," says Kerry J. Stewart, Ed.D., lead study author and director of clinical exercise physiology at Hopkins. "Because as many as 90 percent of adults are at risk for developing high blood pressure, knowing this may point to a cellular target for preventive therapies." Normally during exercise, blood pressure increases to push the flow of oxygen-rich blood throughout the body. However, in some individuals, the response to exercise is exaggerated. Instead of reaching a systolic (upper number) blood pressure of around 200 mmHg at maximal exercise, they spike at 250 mmHg or higher. For the study, published in the April issue of the American Journal of Hypertension, the investigators evaluated 38 men and 44 women ages 55 to 75 who had untreated mild hypertension but were otherwise healthy. Their blood pressures at rest ranged from 130 to 159 mmHg systolic (the upper number) and 85 to 99 mmHg diastolic (the lower number). To measure endothelial function, the researchers first used ultrasound to measure the size of a large artery in the arm. Next they put a tight blood pressure cuff on one of the subjects' arms for five minutes to stop blood flow to the arm, then deflated the cuff, causing a surge of blood flow. They then repeated the artery size measurement, comparing it to the resting measure of the artery. The ability of the blood vessels to expand under these conditions is an indicator of endothelial function. In a second test, they examined blood vessel stiffness -- a marker of early heart disease -- by using ultrasound to measure how fast blood traveled from arteries in the subjects' necks to their legs with each heart beat. Because stiff blood vessels do not absorb any of the pressure behind the blood flow, the faster the blood travels, the more stiff the vessel is. They compared these readings with blood pressure measures taken at rest and while the participants walked to maximal effort on a treadmill. In their analysis, researchers found that higher blood pressures in response to exercise were associated with poorer blood vessel expansion in the arm following the cuff test, suggesting that the endothelial cells failed to dilate enough to handle the extra blood flow. There was no correlation between the stiffness of blood vessel walls or resting blood pressure with increased blood pressure during exercise. Impaired endothelial function is not solely related to high blood pressure, Stewart adds. It also is associated with aging, menopause, high cholesterol, smoking and diabetes, and may be a common process for developing heart disease among all of these risk factors. "It's too early to recommend that people have exercise tests just to measure their blood pressures," Stewart says. "However, careful attention should be paid to exercise blood pressure if measured as part of a medical evaluation, or during a workout at a gym, since it may be a warning that your resting blood pressure may also increase." The study was supported by the National Institutes of Health and the Johns Hopkins Bayview General Clinical Research Center. Study coauthors were Jidong Sung, Harry Silber, Jerome Fleg, Mark Kelemen, Katherine Turner, Anita Bacher, Devon Dobrosielski, James DeRegis, Edward Shapiro, and Pamela Ouyang. - -JHMI- - Stewart, Kerry et al., "Exaggerated Exercise Blood Pressure is Related to Impaired Endothelial Vasodilator Function," American Journal of Hypertension, April 2004;17(4):314-320. On the Web: American Journal of Hypertension Why does blood pressure increase with exercise in the lower after five minutes?Your muscles need more oxygen than they do when you're at rest, so you have to breathe more quickly. Your heart starts to pump harder and faster to circulate blood to deliver oxygen to your muscles. As a result, systolic blood pressure rises.
Why does blood pressure increase with exercise and then lower?It's normal for your systolic blood pressure (the higher of your two readings, taken when your heart is pumping blood through your body) to increase when you take vigorous exercise. This is because your muscles need more oxygen, so your heart has to work harder to deliver it.
Why does my blood pressure fluctuate so much in a few minutes?Everyone's blood pressure rises and falls many times during the course of a single day, sometimes even within minutes. Many factors contribute to these changes, including physical activity, emotion, body position, diet (especially salt and alcohol intake), and sleep deprivation.
How quickly should blood pressure come down after exercise?The Centers for Disease Control and Prevention (CDC) recommends waiting for at least 30 minutes after you exercise to take a reading and resting for 5 minutes right beforehand. But it can take a couple of hours after exercise for your blood pressure to return to its typical level.
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Why does blood pressure increase with exercise and then lower after 5 minutes
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