Book excerpt: In Core Performance Essentials, Mark Verstegen—one of America's most innovative and respected performance coaches—presents a streamlined version of his remarkable Core fitness program. Eliminating all excuses for not working out, this book breaks down fitness essentials into a quick, easy-to-follow routine that takes only 30 minutes and requires no special equipment. There are dozens of workouts designed to improve flexibility, joint stability, and balance—and to create a lean, agile, powerful physique that's resistant to injury and the ravages of age. An ideal beginning workout for those who haven't exercised in years, Core Performance Essentials is also perfect for bodybuilders looking for flexibility, athletes looking to improve performance and decrease the chance of injury, back pain sufferers in need of relief, and, most of all, busy men and women who need to fit their exercise into a crowded schedule.