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Exercise and high blood pressure

Posted Oct 03 2008 11:32am 2 Comments

After my first session in the swimming pool, I felt really terrible and think it was in part due to my blood pressure dropping. That lead me onto reading up about the effects of exercise on a person’s blood pressure. The information below has been gathered from other websites, mostly the Life Clinic website.

Why Does Exercise Lower BP?
Dramatic changes take place in your cardiovascular system when you exercise. Blood flow to working muscles increases tremendously, which causes an immediate drop in blood pressure. The body responds quickly, increasing heart rate and cardiac output to maintain blood pressure at the level required.

When you stop exercising, blood pressure can fall just as dramatically. This is due to a number of factors:

  • When the muscles stop contracting, there is no longer a pump to send blood back to the heart. The heart responds by lowering cardiac output, and blood pressure drops.
  • Concentrations of metabolic byproducts (such as lactic acid) remain in the bloodstream, which causes blood vessels in the muscle to remain dilated. This allows blood flow in these areas to remain high, resulting in a fall in blood volume of the heart, which lowers BP.
  • Body temperature increases with exercise. That causes the blood vessels in the skin to dilate in order to lose the extra heat. This also reduces blood volume in the heart.

In some people, especially those who fail to do a cool-down routine and stand still after exercising, blood pressure drops so much that they faint. But for most, the reduced BP is a desirable outcome. Although it will increase somewhat during the hours after exercise, there is evidence that repeated exercise sessions will gradually lower resting BP, especially in those with borderline or mild hypertension.

Source: American Fitness Professionals and Associates. Blood pressure and exercise.

What happens to my blood pressure during exercise?

Although blood pressure goes up during any kind of exercise, the exact changes are different according to whether the exercise is static or dynamic.

  • Static (or isometric) exercise is defined as a sustained contraction of a muscle group, and is typified by weight lifting.
  • Dynamic exercise is characterized by intermittent and rhythmical contractions; examples are running, bicycling, and swimming.

During static exercise there is a marked increase of both systolic and diastolic pressure (up to 300/150 mm Hg in champion barbell lifters), whereas with dynamic exercise only the systolic pressure increases. Many activities involve a mixture of both types of exercise. Using a Nautilus machine produces the same changes as dynamic exercise.

Dynamic exercise is generally recommended for people with high blood pressure; body building types of exercise are not.

What happens to my blood pressure after I exercise?

Immediately after a prolonged bout of exercise, the blood pressure falls to levels below its resting value. This can occur after any type of exercise which uses large muscle groups, such as walking, running, bicycling, and swimming. The lowest level is seen about 30 minutes after the end of the exercise and may be as much as 20 mm Hg (systolic) below the resting level. Over the next three to four hours, it gradually returns to baseline.

This fall of blood pressure occurs in virtually everybody, particularly after more prolonged periods of exercise (20 minutes or longer), but the changes are more pronounced in people with higher blood pressures– the pressure falls more, and stays down longer, sometimes as much as 12 hours.

That’s it for now - I hope that this information has shed some light on the subject for you!

Comments (2)
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Measurement of elevated diastolic pressure during exercise rather than during rest shows a subtle change in the diastolic pressure level. Blood pressure is measured by the digital blood pressure cuffs every minute during the exercise. Although there are no significant differences noticed generally in systolic or diastolic blood pressure at rest, a higher diastolic blood pressure at peak exercise is the general norm.  The hike in BP may remain for upto 4 hours after exercise.
Mark's brief article is one of the best that I have read. I am going to read it again. I am physical health enthusiast, who believes that exercise is the best defense and offense against diseases. I am 62, or nearly there, and run and walk average of 10 miles at least thrice a week. My interest was finding the resistance level of people who exercise vigorously from heart attack.  
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