Came across this piece on the Beeb about running and aging.
Hardware is nice and having a great body in youth is cool, but this is why you need to make sure you keep it up in your later years.
I thought the study sample was significant and also thought it was neat that the study began when the subjects were in their 50's!
http://news.bbc.co.uk/2/hi/health/7554293.stm