iThe Interval Training Workout, i co-written by a doctor and a certified trainer, shows how interval training can be done practically anywhere and benefit anyone who wants to get healthy. The training has three key components Interval training workouts with brief repetitions of intense exercise alternating with intervals of rest extended workouts longer weekly sessions which allow certain biochemical and muscular adaptations that improve fitness and burn fat and active rest days steady, comfortably paced exercises that help the body rest and recover while still burning calories. The book also offers specific customizable programs for training and tips for assessing performance and tracking progress.