This edition presents the new release of the classic on training theory: revised and newly developed with the collaboration of 22 authors. The traditional range of topics has been expanded to include themes such as "resilience," "training for resilience," "sports medical support," "training and nutrition," and "world status analyses." The first part addresses the nature and fundamental principles of training theory and sports science. The topics of the second part focus on athletic performance and athletic capacity, their structure, and the relevant developmental laws, understood as the scientific foundations of sports training and its methodological design. This includes an exploration of the nature and development of the main factors influencing athletic performance. The third and most extensive part deals with the fundamental questions of sports training.