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I was wondering if exercise only leads to more capillary bloodvessels, or if on the long term you can also grow more of the larger bloodvessels (e.g. if smaller bloodvessels grow wider).

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It's mostly an increase in the capillary system, as the primary function of angiogenesis is to increase the capability to deliver nutrients and oxygen to the working muscle. You don't need larger blood vessels for that, you need more.

However, there are changes to the larger blood vessels (called arteriogenesis) where the larger blood vessels will increase in diameter, and thus allow them to carry more blood.

Note: Both angio and arteriogenesis may or may not happen, it's not a guarantee that if you exercise both will occur. You may get some of one, the other or both, depending on how your body reacts to exercise.

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Wouldn't angiogenesis without arteriogenesis increase resistance of the vessel system? Angiogenesis occurs first. Then, the increased resistance causes increased tension in larger vessels which then stimulates smooth muscle cells to proliferate and increase the diameter of the vessels. –  Darko Sarovic May 27 at 18:30
    
I am not sure, I am familiar with the concepts but haven't studied them since college. However, I would think by adding more capillaries to the endpoint would reduce pressure, not increase it, as the same amount of blood is spread out among X% more capillaries. –  JohnP May 27 at 18:38
    
True, it would. But a process is defined by its slowest step. Or in this case, the flow of blood would be restricted in the vast capillary bed unless the supplying arteries grew bigger. Increasing number of capillaries increases the volume of blood in circulation, which must pass through an arterial system of unadapted size. –  Darko Sarovic May 27 at 18:49
    
@DarkoSarovic - From what I've been reading, the arteries can expand up to 4x as needed, so not as much need to increase in diameter. –  JohnP May 27 at 22:40
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The Frank-Starling idea is a really nice touch. I would expect it to have some effect. That is, it would lower the average tension on the vessel walls. So if you contract 50% less, timewise, then the average total force will be 50% less, and as such the stimulus for arteriogenesis will be more or less 50% lower. –  Darko Sarovic May 28 at 18:09

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