Our club has a 16 week build up program, but it assumes that you've had a few months of running 20 miles a week or more. Personally, I found that (going from 20 mpw to a marathon build-up) too be too steep of an increase; I got injured by attempting marathon training too soon.
As far as being ready to run one, I'd say that if an 18-20 mile (30-32 km) run in training is relatively comfortable, then you should be able to get through the race come race day.
Racing a marathon (e. g., running for place or time) is a different matter entirely. :-)
Post a reply on the Bulletin Board