This book discusses major changes in our understanding of the most prevalent non-orthopedic, sports-related condition - overtraining syndrome (OTS), arguing that it should be considered as the manifestation of burnout in athletes, rather than simply the result of excessive training.

While the chronic adaptations of the cardiovascular and musculoskeletal systems to exercise are well documented, those of the endocrine system are less well known, and adaptations of the hormonal ranges for athletes are yet to be determined. There is also a lack of standardized diagnostic criteria, consistent assessment methods and biomarkers.

This book offers a systematic review of the hormonal aspects of overtraining syndrome, and a comparison with sports-related syndromes triggered by chronic deprivation of different sorts, including the female athlete triad (and its derivative, RED-S) and burnout syndrome of the athlete (BSA). It demonstrates that these conditions, although studied separately from each other, may all be different manifestations of the same condition, leading to 'maladaptive' (dysfunctional forced adaptations to a hostile environment) changes in response to chronic depletion of energy and mechanisms of repair, causing multiple dysfunctions.

The author proposes that OTS/Paradoxical Deconditioning Syndrome (PDS), RED-S/TRIAD and BSA are parts of a same condition, or at least a group of similar conditions. Further, the book offers a chronological overview of OTS, based on preliminary research.

Given its broad scope, this concise reference book will appeal to a range of health professionals. It allows readers, including those without a strong academic background, to gain a systematic understanding of OTS.

Introduction, historical perspective, and basic concepts on overtraining syndrome

Classical understanding of overtraining syndrome
Methodological challenges and limitations of the research of overtraining syndrome
New findings on overtraining syndrome
Clinical, metabolic, and biochemical behaviors in overtraining syndrome and overall athletes
New Understanding, Concepts, and Special Topics on Overtraining Syndrome
The underappreciated Athlete: Overtraining Syndrome in Resistance training, high intensity functional training (HIFT), and in female athletes
Recovery from overtraining syndrome - learnings from the eros-longitudinal study
Female athlete triad (Triad), relative energy deficiency of the sport (Red-s), and burnout syndrome of the athlete (BSA): concepts, similarities, and differences from overtraining syndrome (OTS) 
Special topics on overtraining syndrome (OTS) / paradoxical deconditioning syndrome (PDS)
Practical approach to the Athlete Suspected or at high-risk for OTS
Research and Future Perspectives on Overtraining Syndrome.-Clinical Hormonal Guidelines for the Research of the Endocrinology in Sports and Athletes: Beyond Overtraining Syndrome
Endocrinology of Physical Activity and Sport in Practice: How to Research? Models for the Chronology and Tests of Studies on Athletes.- Novel Insights in Overtraining Syndrome:  Summary and Conclusions.