Featuring the proven 80/20 intensity balance described in Matt Fitzgerald's bestselling book 80/20 Running, this half marathon Level 2 training plan will provide you with the same workout structure used by the most successful runners in the world. TARGET ATHLETE This plan was designed runners who are ready to take their training load up a notch or two in order to improve their half-marathon time. Before you begin the plan, you should be running at least 3x per week, some short efforts at high ...