Book excerpt: From the author of the national bestseller The Complete Book of Abs comes the definitive book on the Next Big Thing in fitness -- core training From the bestselling author of The Complete Book of Abs comes this comprehensive guide to a new movement in fitness: core training. The body's "core" refers to the muscles that comprise the center of your body: the muscles of the abdomen, lower back, butt, and hips. With the increasing popularity of yoga and Pilates -- both of which depend on strong core muscles -- the fitness community has turned its focus from the abs to the core. The Brungardt brothers simple 9-week program is based on over 100 exercises and includes workouts appropriate for beginners and fitness enthusiasts alike. This book will help men and women of all body types and fitness levels to strengthen their core for better mobility, posture, and physique. Get ready to get fit!