Featuring the proven 80/20 intensity balance described in Matt Fitzgerald's bestselling book 80/20 Running, this Ultra Marathon 50 Mile/100 Kilometer Level 3 training plan will provide you with the same workout structure used by the most successful runners in the world. TARGET ATHLETE This plan is a good fit for experienced competitive runners who are prepared to train 2x day some days in pursuit of improved significantly performance. Before you begin the plan, build your training to the ...