Exercise and Blood Pressure
Physical inactivity has been established as a major risk factor for the development of coronary artery disease. In addition to high blood pressure, it also contributes to other risk factors including obesity and a low level of HDL cholesterol. Even modest levels of physical activity are beneficial. Regular aerobic physical activity increases a person's capacity for exercise. It also plays a role in both primary and secondary prevention of cardiovascular disease. There is a relationship between physical inactivity and cardiovascular mortality.
The American Heart Association recommends:
- Vigorous activity for at least 30 minutes three to four days each week at 50–75 percent of maximum heart rate.
- Moderate-intensity physical activities for 30 minutes on most (and preferably all) days of the week provide some benefits. Physical activity need not be strenuous to bring health benefits. It's important to include activity as part of the regular routine.
- Adults who maintain a regular routine of physical activity for longer periods or more intensity are likely to have greater benefits. However, don't overdo physical activity, because too much exercise can result in injury.
- Scientific evidence also supports the idea that even moderate and low-intensity activities, when performed daily, can have some long-term health benefits. They help lower the risk of cardiovascular diseases. Older adults and people with disabilities can gain significant health benefits with a moderate amount of physical activity, preferably daily.
How Exercise Impacts Blood Pressure:
Although blood pressure goes up during any kind of exercise, the changes brought on by exercise vary according to whether the exercise is static or dynamic.
- Dynamic (aerobic) exercise involves large muscle groups engaged in rhythmic, repeated movements. Examples of aerobic activities include jogging, brisk walking, swimming, bicycling and jumping rope.
- Static (isometric) exercise is defined as a sustained contraction of a muscle group and is typified by weight lifting.
Dynamic activities depend mainly on energy derived from consuming oxygen (aerobic). Thus they increase the body’s need for oxygen. Because blood delivers oxygen to the body, aerobic activity challenges the heart and circulatory system to meet this increased need. In dynamic exercise, oxygen consumption and heart rate increase in relation to the intensity of the activity. Systolic blood pressure rises progressively, while diastolic blood pressure stays the same or decreases slightly. Pulse rate rises, and blood flow to the muscles increases. Thus, aerobic exercise exerts primarily a volume load on the heart.
One way to detect changes in cardiovascular activity and oxygen consumption is to measure your pulse rate before, during and after an activity. Aerobic exercise will increase your pulse over the course of the exercise, and the more intense the activity — that is, the more energy demanding — the more your pulse will increase. When you stop exercising, your pulse does not immediately return to normal. Instead it gradually returns to its resting level. The greater your fitness level, the sooner your pulse rate will fall. Isometric exertion involves sustained muscle contraction against an immovable load or resistance with no change in length of the involved muscle group or joint motion. The result is a moderate increase in cardiac output, with little or no increase in oxygen consumption. Despite the increased cardiac output, blood flow to the noncontracting muscles does not significantly increase. This combination of vasoconstriction (the narrowing of blood vessels that restricts, or slows, the blood flow) and increased cardiac output causes a disproportionate rise in systolic, diastolic and mean blood pressures.
Isometric or combined isometric and dynamic (resistance) exercise has traditionally been discouraged in patients with coronary disease. However, it appears that resistance exercise (for example, weight lifting at eight to 12 repetitions/set) is less hazardous than once presumed, particularly in patients with good aerobic fitness and normal or near-normal left ventricular (LV) systolic function. (The heart's main pumping chambers are the ventricles. The heart has a right side that pumps blood to the lungs, and a left side that pumps blood to the body. The left side of the heart must work harder than the right, so the heart's main pumping chamber is the left ventricle.)
Difference between arm exertion and leg exertion
Many activities of daily living require more arm work than legwork. That's why people with coronary artery disease are advised to use their arms as well as their legs in exercise training. Although peak heart rates are similar with arm and leg exercise, heart rate and blood pressure response during arm exercise is higher than leg exercise. Therefore, target heart rates are designated 10 beats per minute lower for arm training than for leg training. Dynamic arm exercise is usually well tolerated by people with coronary artery disease; however, blood pressure may rise and be a concern in some people.
The importance of warm-up and cool-down in exercise
Warming up and cooling down in exercise help your body transition from rest to activity and back again. You also decrease your risk of injury or of being sore. Warm-up should last at least 10 minutes — longer for older people and those who have been sedentary for a long time. Cool-down is especially important. Target heart rate for cool down is 10–15 beats above your resting rate. If you stop exercising too quickly, your blood pressure can drop sharply, which can be dangerous and can also cause muscle cramping.
Make sure that you breathe regularly throughout your warm-up, exercise routine and cool-down. Holding your breath can raise blood pressure and cause muscle cramping.
Always consult your physician before starting an exercise program, particularly if you have high blood pressure or any other pre-existing condition, or if you've been sedentary for a long time. Also try to avoid caffeine, which increases heart rate and blood pressure during physical activity.
In closing, note that there is no good correlation between pulse rate and blood pressure. In people with high blood pressure there's no substitute for measuring blood pressure. Measuring pulse rate does not indicate blood pressure.
Above content provided by The American Heart Association in partnership with Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.
Posted January 2009
