The goal of this book is to help the reader achieve injury-free elasticity, plasticity, and flexibility in sports and exercise. It explains the anatomical components and physiological procedures relative to achieving healthy and long-lasting flexibility. Particular focus is dedicated to the tissues involved in the stretching process, what techniques work and do not work, and how to minimize injuries. The book provides clear definitions on joint flexibility and range of motion (ROM), adaptation and exercise categories, factors which determine adaptive changes in ROM, muscle stiffness, differences between elasticity and plasticity, differences between plasticity and flexibility, connective tissue structure and function, consequences of too little or too much flexibility, basic stretching procedures, pre-competition tapering for peak performance, and many more. The book´s content is based on the author´s fifty years of experience as a former world champion athlete and 7th Dan (degree) martial arts instructor, as well as forty years of experience in high-performance sports medicine, scientific research, and university teaching.