Dr. Philip Maffetone has worked with endurance athletes for more than thirty-five years. He is the author of eighteen books on health and fitness, including The Big Book of Endurance Training and Racing, and the popular textbook Complementary Sports Medicine. Some of his patients have included running guru Dr. George Sheehan, famed New Zealand coach Arthur Lydiard, marathon great Grete Waitz, and six-time Hawaii Ironman world champion Mark Allen. He lives in Oracle, Arizona.Mark Allen is a six-time winner of the Hawaii Ironman Triathlon.