Anyone who runs always hears that one should never run on concrete, always run on dirt trails if possible, to ease the harsh impact on the joints.
But every once in a while I hear someone say “Well, at least he’s running on asphalt. It sure beats running on the sidewalk.”
So how bad is asphalt, compared to concrete? They both seem hard and they support traffic equally, but… I imagine that if I whacked a hammer on blacktop, I might get a loud “thunk” and leave a dent, while on concrete it would definitely ring more and probably not do a thing to the finish. There’s a difference in the surfaces.
But is that difference significant at all to a runner’s joints? Is there any kind of springiness that might help?