From the time the ancient Greek runner Pheidippides ran from Sparta to Marathon to announce the Greeks' victory in the Battle of Marathon, humans have had a compelling interest in endurance running. With over 300 marathons conducted in the U.S. each year, and a few hundred thousand people participating in them, the number of individuals who are interested in running a marathon is substantial and growing every year. Chasing Pheidippides: Marathon Training 101 provides an overview of the process of preparing individuals for a marathon, including tapering and delaying fatigue during the race.