There’s a reason people tell you to put on your exercise shoes and get a workout most days of the week. Exercise is a heart-healthy lifestyle habit that often leads to a reduction in blood pressure. It also has lipid-modifying and anti-inflammatory effects that are good for the heart.
How much can exercise lower blood pressure? An analysis of 54 high-quality studies of exercise and blood pressure found regular physical activity reduces blood pressure by 3.84 mmHg for the systolic reading and 2.58 mmHg for the diastolic reading. These modest reductions are enough to have a favorable impact on heart health.
How does physical activity work its magic? One way exercise lowers blood pressure is by dilating arteries, the blood vessels that carry blood to the tissues of the body. As the artery relaxes, blood pressure drops. The study showed that exercise reduces blood pressure in people with hypertension and men and women who have a healthy blood pressure.
What Happens to Blood Pressure Readings During a Workout?
During an exercise session, blood pressure temporarily rises due to activation of the sympathetic, or “fight or flight” nervous system. After a workout session is over, blood pressure gradually comes back down. Not surprising! Exercise places considerable demands on the heart and it’s not uncommon for the blood pressure of a healthy person to rise as high as 200 mmHg at the peak of an exercise session. The increase is because the heart has to pump harder and faster to deliver enough blood and oxygen to the working muscles. More intense exercise typically leads to greater increases in blood pressure than lower intensity workouts.
An increase in blood pressure when exercising is normal. However, certain people experience a larger spike in blood pressure during physical activity. The health community calls this exercise hypertension. Research shows that people who experience a higher spike in blood pressure during exercise are at greater risk of developing hypertension later on. In fact, measuring blood pressure during exercise could be a good screen for identifying people at high risk of high blood pressure. Yet, we get blood pressure readings at rest. In fact, your physician probably asks you to sit and relax for five minutes before checking your blood pressure. So, most of us don’t know how high our blood pressure rises during a workout.
Exercise Hypertension and Endothelial Function
Why do people at higher risk of hypertension develop a bigger spike in blood pressure during exercise? Researchers believe that people with exercise hypertension have arteries that don’t dilate as much as a healthy individual’s arteries during exercise. The cells that line the inner wall of arteries are called endothelial cells and, collectively, they make up the endothelium. These cells are so vital to the health of arteries that scientists sometimes refer to them as a separate organ like the lungs or digestive tract.
The endothelial cells have some unusual functions that other cells don’t have. For one, they produce a gas called nitric oxide that causes the blood vessel to open wider. Makes sense, doesn’t it? If you fill a balloon with gas, it expands in size. Likewise, if endothelial cells in an artery produce more nitric oxide gas, the artery expands. In turn, this lowers blood pressure. Endothelial cells are also involved in blood clotting and in regulating inflammation within the walls of arteries. Poorly functioning endothelial cells play a key role in the development of hypertension and cardiovascular disease.
As mentioned, people with exercise hypertension have arteries that don’t dilate as much during exercise. Therefore, they have blood vessels that are less equipped to handle the extra blood that courses through the arteries during exercise. Researchers at Johns Hopkins University believe that the endothelial cells in people with exercise hypertension don’t release as much nitric oxide during exercise relative to people who don’t develop higher blood pressure spikes during exercise. When endothelial cells release nitric oxide, the gas widens the blood vessel, blood flow increases, and blood pressure drops. This helps limit the rise in blood pressure during exercise. However, if the cells release less nitric oxide, this response is not as pronounced. Rather than a peak blood pressure during exercise of 200 mmHg, which is expected, people with exercise hypertension might experience higher spikes of 230 mmHg or higher.
How Would You Know if You Have Exercise Hypertension?
Since we don’t routinely check blood pressure during exercise, the only way the average person knows they have a higher blood pressure spike during exercise is if they get a cardiac stress test. During a cardiac stress test, technicians constantly monitor your heart tracings, heart rate, and blood pressure. They would know how high your blood pressure goes during the peak of exercise.
You could also check your blood pressure before, during, and after exercise. If you spike consistently above 200 mmHg, it suggests that you may have reduced endothelial function and are at higher risk of developing hypertension in the future. But, be aware that endothelial function changes with age. People tend to develop high blood pressure later in life as endothelial function worsens due to the aging process. People who smoke, those with lipid abnormalities, and men and women with diabetes tend to have a worse endothelial function too. These are all risk factors for cardiovascular disease as well.
Are There Ways to Improve Endothelial Function?
Exercise transiently improves endothelial function. It also helps with weight control. This is important because obese people have higher levels of inflammatory factors that worsen endothelial function. Not smoking, controlling blood sugar, and optimizing blood lipids helps the endothelial cells function better too. Certain foods have an impact on blood vessels and their ability to dilate too. For example, green, leafy vegetables and beets contain nitrates that are precursors to nitric oxide. When you eat lots of these greens, nitric oxide levels increase and blood pressure drops. Also, the amino acid arginine increases nitric oxide production and improves endothelial function.
The Bottom Line
Track your blood pressures closely and check it at different times of day, including during or after a workout. A single blood pressure reading at a doctor’s office doesn’t provide enough insight into the health of your blood vessels. So, do some of your tracking and monitoring–and make sure you’re leading a heart-healthy lifestyle!
· Ann Intern Med. 2002;136(7):493-503.
· Circulation Research. 2016;118:620–636.
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