I have been working out at the gym, running, cycling and in line skating since 1977. Below is an article from the NYT about the effects of running on the aging process. One would think that the equivalent cycling would have the same or similar effect. One must keep in mind that running 50 miles per week is a tough standard to maintain.
How long are your Telomeres?
http://well.blogs.nytimes.com/2010/0...=me&ref=health