Book excerpt: Strengthen Your Core is the book for individuals who want a safe and effective core exercise program to improve posture, enhance performance, and strengthen from head to toe. Over one hour of video tutorials accompany Strengthen Your Core that explain the key concepts in core strengthening. Video content is available online at www.melioguide.com. The book covers the theory behind core strength and provides detailed descriptions of each of the Plank and Side Plank poses for all client levels-from beginners just starting to build core strength to advanced elite athletes wanting to gain that competitive edge. Core exercises are organized by level-Beginner, Active, Athletic, and Elite. Over 70 Plank and Side Plank poses are described (with photo illustrations).