Can it be done? wrote:
Has anyone run a marathon on just a diet of long runs, easy miles, and thresholds (at goal pace).
I don’t think I’ve ever heard anybody define “threshold” as “goal marathon pace” before.
My gut feeling is if your current marathon PR shows that you are an underperformer at the distance (e.g. a 16:30 guy who has only managed a 2:55), you could pull it off that way and run a decent PR. If you’re already running a marathon in line with your half and 5k PRs, there’s no way this makes you faster because you need speed development to raise your ceiling.
Seems like this would take an assload of mileage, and I don’t see any upside to not doing work at least once a week at faster than goal pace. I don’t know why you would do it unless you just felt like being a contrarian.