Endurance sports like running will lead (even in healthy individuals) to very very mild cases of orthostatic intolerance . If you go from sitting to standing, you might get lightheaded for a few seconds as the body is too slow to react. More here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2343225/pdf/tjp0...
Interesting. I've been a runner for over a decade and run 50+ miles/week. I experience light-headedness going from sitting to standing a few times a week.
Sometimes I have to sit down in the bedroom door frame so that I don't faint and collapse. Once I'm up though, my body is full of vigor.