Blood Pressure and Exercise
Blood Pressure Levels – What happens to blood pressure during exercise? Different kinds of activity affect blood pressure differently. 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 8 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.
Source: American Heart Association