12 Week Marathon Training Plan This plan is built for an experienced runner who can handle 60-80 miles per week or 7 to 8.5 hours of running a week. This plan incorporates 6 days of running a week all on single runs with one day off a week. This runner is likely very experienced and very competitive and prepared to take on a significant training load. This plan is designed to be 12 weeks of marathon specific training, it is advised to start this plan coming off of an aerobic development, 5K, ...