This 20-week beginner 100k ultramarathon training plan is designed for athletes who are new to the ultra distance but already have a solid running base. The focus is on gradually building durability through consistent mileage, long runs, and strategic back-to-back efforts.The plan emphasizes time on feet and recovery to help athletes adapt safely to the demands of a 100k race. With a balanced approach that prioritizes sustainability and periodization, this plan prepares first-time 100k runners to confidently reach the start line, and finish strong!

In this plan, most weekday-runs are structured and intended to be done as road-running, while most weekend long runs are unstructured and intended to be completed on the trails. You should be able to comfortably average 20 miles per week before starting this training plan.