I’ve got 12 weeks left in my 18 week marathon plan (level 2, power-based), but my race is 13 weeks away. Where would it be best to insert an extra week of workouts (and of what type) to maximize race fitness at the end of the block? Is there a week of workouts I could duplicate/repeat sometime along the way?
This type of adjustment is best to make up front, when the training load is still a couple of steps below peak level. Given where you are in the plan, the simplest adjustment is to complete Week 6 (a recovery week), then repeat Week 5, and then finish out the plan from Week 7 on.