Based on the latest scientific developments and prospects, with critical use of recent documented scientific evidence (evidence-based practice) from international literature. Necessary for every scientist coach (regardless of sport) and applied health professional (dieticians, sports doctors), as well as for the better education of undergraduate/postgraduate students.

The content of the textbook covers a wide range of specialized thematic units with documented scientific information and detail, such as:
- Developmental pediatric elements and basic knowledge of developmental biology
- Foundations of athletic development, motor control, and comprehensive athletic assessment in developmental ages
- Training methodology for strength and power development for all sports
- Specific topics in adolescent sports pathology
- Fundamental knowledge / contemporary trends in applied nutrition for athletes.

Given that the acquisition of knowledge is a continuous personal journey of exploration, it is imperative for the progress and development of coaching in developmental ages to have a common starting point of documented scientific knowledge for all coaches. Each colleague will find in this textbook a clear, logically structured operational framework of actions / activities regarding the guiding principles for the development of fundamental training programs for pre-adolescent children.
Documented answers are provided to several controversial issues through the summary of theoretical and practical knowledge. An effort has been made to systematize the scattered knowledge in international literature with clarity, simplicity, and classification of specific training goals, in order to be accessible to every Greek colleague with practical applications and specific criteria of athletic performance proposed for each age.

This textbook belongs to every anonymous trainer-coach, with pedagogical orientation and creative abilities, who initially must inspire and transform into action the love of young children for sports. In a subsequent stage, systematically, they must evaluate, assess, and diagnose the abilities/athletic skills of each young athlete, in order to guide them later to the appropriate sport with increased chances of distinction.
Every coach works tirelessly, providing such motivation to the physical and mental reserves of the young athlete, in order to ensure:
- the longest possible athletic career for them
- the preservation of their enthusiasm
- the daily struggle to become a "fighter" and improve themselves
- the formation of their character.