What about martial arts? Not the full-contact ones, I guess, but aikido comes to mind when I think of the one where a person could keep practicing till very old age.
Helio Gracie comes to mind (http://en.wikipedia.org/wiki/Helio_Gracie). Apparently he was still training at the age of 95. Some of the videos of him in his 80s in YouTube show him still to have been a force to be reckoned with.
