This intermediate marathon plan assumes a starting fitness level of easily being able to run 25 miles per week with at least a 9-mile long run. It starts off running four days per week and, by week 12, increases to running five days per week, minus a few easier weeks. It maxes out at 43 miles per week with one 20 miler. Level Intermediate Target Marathon Time ~3:35 to ~3:55 Weekly Mileage Progression 20, 21, 23, 25, 27, 28, 21, 33, 35, 36, 37, 39, 28, 40, 40, 43, 39, 32 Long Run ...