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.

Related information Lifestyle changes - Exercise