High blood pressure is sometimes called the silent killer because it usually appears without symptoms and can go undiagnosed for years while seriously damaging the heart, blood vessels, and kidneys. Untreated hypertension can cause atherosclerosis—plaque deposits and fibrosis of the arteries—which can lead to heart attack, stroke, kidney failure, and intermittent claudication (pain and weakness in the legs from inadequate blood supply to muscles).
The positive effects of regular exercise on blood pressure are well documented. Physical activity can reduce blood pressure both for people with hypertension and for those whose blood pressure is within the normal range. Exercise can help delay or prevent the development of hypertension. The incidence of hypertension is 30%–50% higher among people who are less active and less physically fit. There is evidence that a lack of exercise, smoking, and alcohol use interact with genes to cause high blood pressure.
Even a small increase in daily exercise can have a significant effect on blood pressure. Increased physical activity is often the initial treatment of choice for patients with mild to moderate high blood pressure. Exercise can be as effective as many medications in lowering blood pressure, without the unpleasant side effects, and has the added benefits of weight control, reduced blood glucose and cholesterol levels, improved heart function, reduced stress, and an increased feeling of well-being.
Approximately one in three American adults—nearly 75 million people—have hypertension. More than one-half of those over age 60, including almost 60% of those aged 65 and older, have hypertension. Among adults aged 45–64, nearly 34% have been diagnosed with high blood pressure. A 2011 study found that about 19% of Americans aged 24–32 may have high blood pressure. Fewer than 3% of children have hypertension. Of all adults with the disease, only about half of them have their blood pressure under control. In 2014, blood pressure was a contributing factor in nearly 1,100 U.S. deaths per day.
Despite its association with age, high blood pressure is not a normal part of aging. It is more likely to be associated with excess weight or obesity. Three-quarters of those with high blood pressure are overweight or obese. Only about 15% of adults of healthy weight have hypertension. Adults who engage in vigorous exercise for at least 30 minutes at least three times per week are one-third less likely to report having high blood pressure. Among adult Americans, blacks are more likely than whites to report having high blood pressure and Hispanics are less likely.
Blood pressure is the amount of pressure that circulating blood exerts on the walls of the arteries. Blood pressure depends on the rate and strength of heart contractions, total blood volume in the circulatory system, and elasticity of the arteries. Very small arteries called arterioles regulate blood flow. When the arterioles tighten or constrict, the heart must pump harder to move blood through smaller spaces, thereby increasing the pressure inside the blood vessels.
Exercise has dramatic effects on the cardiovascular system. The increased flow of blood to working muscles causes an immediate blood pressure drop, to which the heart responds by increasing its rate and output to raise blood pressure.
Blood pressure is measured with a sphygmomanometer. It measures the degree to which pressure inside the arteries raises a column of mercury, expressed as millimeters of mercury (mm Hg). There are two numbers to the measurement: The top or first number is the systolic pressure—the maximum pressure through an artery as the heart contracts and pushes blood into circulation; the second or lower number is the diastolic pressure—the minimum arterial pressure as the heart relaxes after a contraction.
Adult blood pressure categories are:
Exercise causes a temporary rise in blood pressure to increase circulation to the muscles. It is not unusual for systolic pressure to rise by 30–50 mm Hg during exercise. Blood pressure returns to its resting level nearly immediately after exercise. The most accurate blood pressure readings are obtained before exercise or at least one hour after exercise.
Most people with hypertension have only a mild to moderate increase in blood pressure that may be treated with exercise, weight loss, and reduced salt intake. However, the higher one's blood pressure, the greater the risk of adverse health consequences. People with prehypertension are likely to develop hypertension unless they make lifestyle changes, such as engaging in more exercise. Patients whose blood pressure is within the normal range due to medication have their blood pressure under control but are still considered to have hypertension.
Children and teens have lower systolic and diastolic pressures that are sex-, age-, and height-specific. Childhood hypertension is a serious condition that is most often secondary to another condition, such as heart or kidney disease. However, children with a family history of hypertension should have their blood pressure checked regularly. The American Heart Association recommends at least 30 minutes daily of moderate- and high-intensity exercise for all children aged five and above. Hypertension occurring with exercise in children or teens can be a symptom of a birth defect called aortic coarctation, in which part of the aorta (the major artery leading out of the heart) is narrowed. Teens with severe hypertension should avoid certain sports until their blood pressure is controlled.
Both aerobic and resistance exercise can lower blood pressure over the long term, provided they are performed on a regular basis. The usual recommendation is at least 30 minutes on most days of the week, although more may be necessary for those needing to lose weight. Three ten-minute sessions are as effective as one 30-minute session. People who are already physically active might be able to lower their blood pressure by increasing the intensity or duration of their current exercise.
Aerobic exercise is any physical activity that increases the heart and breathing rates—such as walking, jogging, biking, or swimming. Exercise does not have to be particularly vigorous or sustained to affect blood pressure. Climbing stairs, mowing the lawn, raking leaves, gardening, or scrubbing a floor can be aerobic. Walking or other mild exercise can reduce blood pressure as much or even more than strenuous exercise such as jogging. Water aerobics can afford the same benefits with much less stress on the joints. Numerous studies have also demonstrated a reduction in blood pressure with tai chi. Even many work and recreational physical activities help lower blood pressure if they cause exertion.
Exercise raises blood pressure as more blood is pumped to deliver oxygen for the activity. During aerobic exercise, systolic blood pressure increases slightly with the rise in heart rate. Diastolic blood pressure remains the same or can even drop. Static or resistance exercises can cause both systolic and diastolic pressures to rise because muscle contractions can constrict blood vessels. Isometric exercise (contracting a muscle without moving it) increases blood pressure more than isokinetic exercise, such as throwing a ball or running, in which muscles are moved through their full range of motion.
Exercise-induced blood pressure changes usually return to normal immediately after exercise. An inappropriate high-blood-pressure response to exercise in nonathletes is a predictor of future resting hypertension.
The mechanisms by which exercise reduces resting blood pressure are not entirely clear. Regular aerobic exercise strengthens the heart and increases stroke volume. That means the amount of blood pumped with each heart contraction, the stronger the heart and the less effort required for pumping, which reduces the force on the arteries. Also, the higher the stroke volume, the less often the heart must pump, which lowers blood pressure. Exercise also increases the pliability of blood vessels, improving their response to changes in blood pressure and volume.
An exercise program for controlling blood pressure should begin gradually. Older people and those with medical conditions or significant health risks should consult their physician first. Because nearly half the risk of having hypertension is inherited, adults should have regular check-ups as they age to determine if blood pressure is above normal.
Exercise should be a routine, enjoyable part of daily life, since its blood-pressure-lowering benefits are rapidly lost if exercise is discontinued. Variety—walking, swimming, or attending an aerobics class on different days at different times—or exercising with friends or family members can help develop and maintain an active lifestyle.
Blood pressure can fall as dramatically after exercise as it rose with exercise. Without muscle contraction, blood is no longer pumped back to the heart with the same intensity. The heart responds by lowering cardiac output, causing blood pressure to fall. The metabolic by-products of exercise, such as lactic acid, can remain in the bloodstream, causing the blood vessels in muscles to stay dilated and blood flow to remain high, dropping the blood volume and lowering pressure. Higher body temperature from exercise causes blood vessels in the skin to dilate to release excess heat, further reducing blood volume. Failure to cool down at the end of exercise can induce such a sudden drop in blood pressure that it causes fainting. During the hours following exercise, blood pressure rises back to its normal resting value.
Training with weights that are too heavy can cause a temporary but dramatic rise in blood pressure. Therefore, a physician should be consulted before individuals begin weight training. It is important to learn to use weights properly and to breathe easily and continuously through each lift so as not to cause dangerous spikes in blood pressure. It is better to increase the number of repetitions with lighter weights than move to heavier weights that can raise blood pressure. The activity should be stopped immediately in the case of severe shortness of breath, dizziness or faintness, pain in an arm or jaw, irregular heartbeat, excessive fatigue, or pain, tightness, or pressure in the chest.
Exercise can lessen the negative effects on blood pressure of a high-salt diet. The more exercise, the less blood pressure appears to respond to dietary salt, possibly because of salt loss through sweat or excretion or via a mechanism that relaxes blood vessels.
For people with normal blood pressure, regular exercise can help prevent an increase with age, as well as help to maintain a healthy weight, which lowers the risk of hypertension. Regular exercise can help prevent those with prehypertension or a family history of high blood pressure from developing hypertension.
See also Exercise ; Hypertension .
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Margaret Alic, PhD
Revised by Teresa G. Odle, BA, ELS