The first response is actually quite correct. Crossing your legs is bad for you. I know, it's of a fashion for skirtgirls that want to remain modest; but if you're hopping on a bike in a skirt... The guy behind you at the light has his camera phone out btw

So if you're in sports gear, don't do it. In fact, you may do better to actually lie down rather than sit, to get your legs and your heart at the same elevation and help your blood pressure come down. After you've walked off the high heart rate, of course; don't dead drop from high exertion to relaxation. I've done that when meditating and my body was pretty seriously jacked (when meditating, this is extremely apparent).