I, too, was a fainter when I was
a teenager and early twenties. After
riding bike, I would stop the
bike and faint. It turns out that I have an adrenal problem where exercise, licorce, caffeine brings my heart rate up extremely fast at a fast rate. I have not been on a bike in 24 years now and cannot run and have to be careful not to walk too fast. The cardiologist told me that it will not shorten my lifespan and not to worry about it.