High-intensity interval training (HIIT) is an extraordinarily effective form of training that mixes high- and low-impact activities during periods ranging from seconds to eight minutes. In Dr. Len Kravitz, a National Fitness Hall of Fame inductee and internationally-renowned exercise scientist for the past thirty-six years, explains what HIIT is and how it effects your entire body (externally and internally), gives 50 workouts and a plan to whip you into shape fast, and presents a wealth of nutritional and other advice to further its impact. HIIT was recently rated the #1 new fitness trend by the American College of Sports Medicine and is the key to staying fit for celebrities like David Beckham, Britney Spears, Hugh Jackman, and Scarlett Johansson. In addition to fat loss, it’s been proven to have major health benefits on blood pressure, diabetes, and cholesterol. Through this groundbreaking volume you'll learn why, and see how to get fit quick and have a fun and truly sustainable exercise program, no expensive personal trainer required.