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 is designed for experienced competitive runners who are prepared to train 2x a day some days in pursuit of significantly improved performance. Before you start, you should be running at least 3x per week, with short efforts ...