Vasodilation: Why it Happens and What it Does

4. Exercise

The regulation of blood flow to exercising muscles is closely coupled to the need for increased oxygen and nutrients when the metabolic demand of the muscles increases. This process enables exercising muscles to work effectively and ensures chemicals do not build up and cause cramps.

The body is about 40% muscle, and blood flow to muscles can increase by almost 100 times during intense exercise. The heart works harder to pump more blood to the muscles, but it cannot provide enough blood in this way. Vasodilation in the muscles ensures the blood flow is adequate. Chemicals in the muscles and blood vessels prompt expansion. The release of norepinephrine can cause vessels to narrow (vasoconstriction), so during exercise, another mechanism blocks the effects of norepinephrine, allowing vasodilation and an increase in muscle blood flow.