20 and 40 minutes are great benchmarks if your 50 years old Ed G 11/14/03 2:30:44 PM ET
I'll be fifty next September and I can run a 5k in 20 minutes and a 10K in 42 minutes.
a person training for a marthon in thier thirties or younger should have no problem running a 5k in 18:30 or less and a 10K in under 40. Heck, if you can't do that you might as well be walking alongside north.