There is a comment in Richard Askwith's Running free about nettles stimulating the blood circulation. If this is true, I get my circulation stimulated at some point on most of my training runs between May and October. No, I'm not deliberately indulging in some kind of self-flagellation; it just happens that many of the otherwise excellent paths that I use for my runs have short stretches where they are encroached on by nettles. But does anyone on the forum have any definitive information about the effect of nettle stings on circulation?