Blood pressure varies over the course of the day, depending upon what you’re doing. Yet it tends to follow a daily pattern. Blood pressure drops to its lowest point during sleep as the parasympathetic, or rest and relax portion of the nervous system, takes over. As morning draws near, blood pressure begins to rise an hour or two before you awaken to prepare you for the upcoming day. Throughout the day, it will continue to go up and reach a high in the mid to late afternoon. These trends are influenced by your internal biological clock and circadian rhythms.
Blood pressure also changes with activity. When you exercise, your sympathetic or “fight or flight” nervous system predominates over the parasympathetic component. In response, your heart rate increases to deliver more oxygen to your muscles and your blood pressure rises. You can feel your heart rate increase as you launch into the warm-up and speed up even more as your workout becomes more intense. Your blood pressure also rises. These changes are normal and almost everyone experiences them.
Some people have a more exaggerated rise in blood pressure in response to exercise, and studies show that this more pronounced rise in blood pressure with exercise is a marker for higher risk of cardiovascular disease and early mortality. In other words, how your heart responds to exercise says something about how healthy your heart is.
Endothelial Function and Cardiovascular Disease
How are exercise blood pressure and heart health related? Researchers believe that poor endothelial dysfunction explains why some people have a more exaggerated blood pressure response to exercise. When you first start to exercise, your arteries constrict, and this raises blood pressure. In response, healthy arteries release more nitric oxide, a gas that dilates the blood vessels, helps them expand, and prevents a sharp rise in pressure. Studies show that people who have a sharp rise in blood pressure in response to exercise have arteries that don’t produce as much nitric oxide, a gas that inflates the blood vessel, much like blowing up a balloon.
Poor endothelial function means the arteries that carry blood are stiffer, and when arteries are stiff, blood pressure increases. For years, cardiologists questioned the significance of exercise-associated spikes in blood pressure. The thought was that blood pressure spikes brought on by exercise weren’t significant and didn’t require treatment in people who don’t have hypertension at rest. However, this thinking is changing. It’s still not clear whether spikes in blood pressure during exercise are a phenomenon that needs treatment, but leading cardiologists believe it’s a concern and we shouldn’t ignore blood pressure spikes brought on by exercise.
Does science support this idea? A study published in the journal Hypertension found that an exaggerated blood pressure response to exercise is a predictor of future hypertension. As such, it raises a red flag for future high blood pressure and possible heart problems. This was true irrespective of other risk factors for cardiovascular disease.
In fact, a study found that an exaggerated rise in blood pressure during exercise was linked with a 3 to 4-fold greater risk of developing hypertension. It’s possible that the stress of exercise unmasks the tendency to have hypertension. So, screening for blood pressure spikes during exercise could be a way to screen for hidden heart disease.
Screening for High Blood Pressure During Exercise
Most people don’t know how their blood pressure responds to exercise because we don’t check it when we’re working out. If your doctor recommends a cardiac stress test, they document your heart rate and blood pressure during exercise, so that would give you some idea of whether your blood pressure rises too much. However, you could take your blood pressure before exercise, several times during a workout and right after. Write down the values and discuss them with your physician. If they’re jumping a lot during exercise, you may need to monitor your blood pressures more closely, even if you don’t have hypertension at this point in your life.
Other Causes of Poor Endothelial Function
Poor endothelial function or reduced ability of your blood pressures to expand contributes to high blood pressure and cardiovascular disease. We also develop worsening endothelial function with aging. In women, this is common after menopause. Elevated cholesterol, diabetes, and smoking are other contributors to poor blood vessel function.
On a positive note, studies show aerobic exercise improves endothelial function. In fact, animal studies show a single exercise session can reduce arterial stiffness and enhance blood vessel function. Human research also confirms this. Studies show this is true even in the elderly, those with cardiovascular disease, and those who are at high risk for heart disease.
The Bottom Line
Monitor your blood pressure closely, especially after the age of 50. Measure it in the morning and evening so you can compare the two readings. You don’t have to do this every day but several times per week to determine the pattern. If possible, get some measurements before, during, and after exercise and write them down. If you’re already on blood pressure medications and still get spikes during exercise, your physician may be able to adjust your medications to reduce the severity of the spikes.
Cardiologists now think that it may be just as important to optimize blood pressure during exercise as at rest. Sharp rises in blood pressure place added strain on your heart and blood vessels. So, know your numbers, but keep exercising! It’s too important for heart health not to do it.
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