My only input into this is that I have a pretty severe case of "Exercise-Induced Vaculitis" or "Golfer's Vasculitis." It's supposedly a benign condition, but I can tell you it's caused some permanent discoloration and damage to the small surface capillaries in my legs. When I'd walk the golf in hot weather, the back of my calves would turn beat red like they were sunburned, but there was texture to it as the capillaries were inflamed.