The Book on Overtraining Syndrome


June 27, 2021

Overtraining syndrome is amongst the diseases with the largest prevalence in elite athletes. And not only in elite athletes.

Its occurrence has been first hypothesized when athletes began to present unexplained decrease of sports performance, in the 1940s and 1950s. By that time, the concept 'the more - the better' in terms of training was prevailing, and competitiveness was on the raise due to the Olympics that restarted after the World War II (WWII), during the Cold War, when performance in sports had unprecedented political weight. Some athletes started to show a progressive loss of performance that responded paradoxical to increase of training load, i.e., the more they trained, the worse they performed, and which were unresponsive to recovery interventions. 

The new paradox observed in some athletes has been unsuccessfully investigated for an extensive range of causes that could also justify the underperformance. 

A syndrome of unexplained underperformance in athletes has then emerged, that was strictly related to excessive training. Hence, the term overtraining syndrome was intuitively coined, although only decades after the first descriptions of overtraining.

From the perspective of excessive training as the sole trigger of overtraining syndrome, changes in training patterns resulted from the learnings of the key relevance of the training periodization with the consequent elution of excessive training would mitigate this syndrome, which has failed unexpectedly, and overtraining syndrome in athletes persisted. At the same time, the lack of response to training adaptations was expected if one considers that the underlying mechanisms that demonstrated the excessive training as the intrinsic factor of loss of performance had never been elucidated until then. 

Since changes in the paradigm of training programs were not enough to resolve overtraining syndrome, other triggers were likely present, although these have not been extensively investigated. In result, a lack in the knowledge of what really triggered overtraining syndrome remained unsolved. 

Meanwhile, while the majority of elite athletes experiment at least one episode of overtraining syndrome, the growing number of non-professional athletes that practiced sports at extremely intense levels, resembling professional athletes, with concurrent rigid practices in other living patterns, led to an increase of overtraining syndrome incidence - and popularity. 

The use of the term overtraining has been spread among athletes, sports coaches, and more recently in specific and general media. However, more than 90% of the use of the expression was designated to describe other states than overtraining syndrome, while unsubstantiated characteristics and manifestations alleged to be part of overtraining syndrome that has been universally accepted led to an almost general misinterpretation and misunderstanding of overtraining syndrome, with consequent misdiagnosis in the majority of the cases. The two hallmarks of overtraining syndrome, the loss of performance and the lack of an apparent explanation for impaired performance, has become secondary in the context of the broad use of the term overtraining. 

With the general misuse of the term overtraining, the loss of the essence of overtraining syndrome and the reduction in scientific production on the field that occurred after the decade of 1990, those suffering from this condition remained underappreciated, which led to the end of the career of several professional athletes. 

Fortunately, the interest on this syndrome has been recovered recently, with the publication of the first and only guidelines on overtraining syndrome, in 2013.   

The guidelines on overtraining syndrome helped educate sports-related health providers to learn of the actual characteristics of overtraining syndrome, and the unexpected decrease of sports performance has become central again.

However, unanswered questions regarding overtraining syndrome pathophysiology, triggers, mechanisms, and effects that have only been partially addressed by classical theories, still prevailed. 

In this context, several novel studies have recently had the opportunity to revisite OTS from a more comprehensive perspective, that comprised wide different aspects to be potentially correlated with the development of the syndrome, and did not limit the occurrence of OTS to training patterns. 

Consequently, multiple novel findings have been unveiled, which provided embodiment for novel insights and novel concepts that have been that resulted in a novel understanding of overtraining syndrome. The aim of the book is to present the novel insights, hypotheses and proposed functioning of overtraining syndrome arisen from the novel uncovered mechanisms. 

In short, the recent discoveries allowed the realization that overtraining syndrome is resulted from sum, respective intensity and interactions between chronic combination of deprivations from excessive efforts, including caloric and protein relatively insufficient intake, non-repairing sleep, lack of compensatory reduction of training load and concurrent intense physical and cognitive demands. These chronic deprivations build a hostile tissue environment chronically depleted from energy and repairing mechanisms, which forces the occurrence of multiple adaptations aiming to keep surviving and functioning. The outgrowth adaptations are overwhelmingly dysfunctional (‘maladaptations’), resulting in multiple hormonal, metabolic, immunologic, inflammatory, and muscular abnormalities, that eventually lead to the main manifestations of overtraining syndrome, including mental and physical exhaustion, pathological muscle soreness, loss of multiple abilities in physical performance, increased predisposition to overall infections, and burnout-like signs and symptoms. Hence, a chronically misadjusted routine, rather than excessive training alone, is the key trigger of overtraining syndrome.

The more comprehensive understanding of overtraining syndrome as being a condition that encompasses a broader number of factors, mechanisms and characteristics is not limited to its intrinsic features. In a bigger picture, overtraining syndrome is highly representative of an ample and diverse range of aspects. 

Overtraining syndrome is the representative dysfunction resulted from a society that increasingly worships the high performance in major aspects of life simultaneously - physically, intellectually, socially, financially, professionally, sexually and psychologically, towards an unachievable perfection and artificial robotization of human being. 

Since high performance depends on overcoming specific deprivations that occur at great extent, overtraining syndrome is also the representative condition of a cluster of diseases derived from multiple deprivations - deprivations of food, sleep, resting and indulgences - that generates a state of low energy availability (LEA) and consequent chronic energy deprivation, which eventually induces a decrease of sports performance, and share multiple similarities with burnout syndrome. These conditions comprise the female athlete triad (TRIAD) and its expanded concept of relative energy availability of the sport (RED-S), the burnout syndrome of the athlete (BSA), and pseudoOTS and OTS-like states.

Collectively, the multiple similarities allow hypothesize that all these dysfunctions may be different poles of a same, broader condition, that has been termed as the "impaired athlete", although extensive research is needed to confirm this hypothesis. Indeed, if athletes diagnosed with TRIAD or RED-S were assessed for overtraining syndrome, a good part would also have diagnostic criteria for this syndrome. 

Overtraining syndrome is the representative consequence of the current pathological anthropological context that considers strict eating as a quality to be worshiped, with an implicit sense of superiority of those that can fully control of their dietary patterns. From a society perspective, the more implicit and camouflaged version of eating behaviors disorders is notorious, and can be easily recognized by the increasing veneration of excessively lean bodies allied to the growing fat-phobia and obesophobia. 

The presence of apparent body fat, even without overweight, has become an indirect and almost unconscious marker of weakness from excessive indulgences and allowances, as 'denounced' by the presence of larger (but not large) skin folds.  

Correspondingly, unlike before, when body fat was secondary if one aimed to improve performance, the simultaneous seek for both performance and decreased body fat due to cultural reasons propitiates stricter regimens that naturally lead to deprivations.

Overtraining syndrome is the representative dysfunction of the decreased performance as the final result of dysfunctional adaptive processes, that may also occur under states that are not necessarily labeled as a specific diagnosis. 

Despite the description of BSA, OTS better represents the model of burnout syndrome in athletes, in particular regarding the lack of simple, frank and ubiquitous markers or mechanisms that explain, the challenges to perform a correct diagnosis, and the high individuality of the clinical, biochemical combination of manifestations. From a more comprehensive analysis, athletes with OTS present features equivalent to those in the recently recognized burnout syndrome. 

In addition, overtraining syndrome represents the complexity of when the adaptive models in athletes get disrupted.

Overtraining syndrome is also the representative example that one-size-fits-all is by far the most inappropriate approach to athletes. The inappropriateness of the excessively protocoled assessment as the only tool to diagnose more complex syndromes can be extended to general population. While attempts to fit overtraining syndrome into few patterns of presentation failed due to its complexity, a more accurate comprehension of overtraining syndrome may have been precluded. 

Overtraining syndrome is the demonstrative representation that the lack of overt biochemical abnormalities does not necessarily mean lack of dysfunctions; on the contrary, dysfunctions tend to be harder to be detected because of the complexity of the non-obvious alterations. And indeed, when we go deeper in the analysis, and only after a multiple-comparative analysis, we realize that dysfunctions do exist, but they are hidden by the previous optimizations that these parameters underwent in this population of athletes. Perhaps, its complexity associated with several types of "unexplained complains" including those in joints and muscles have spread its common yet inappropriate employment of diagnosis of overtraining syndrome in clinical practice. 

The early stages of overtraining syndrome, termed as functional (FOR) and non-functional overreaching (NFOR), represents the continuum that this syndrome undergoes before its end-stage, and demonstrates that overtraining syndrome is resulted from persistent  ignoring of the signs of alert that occur through repeated episodes of overreaching, in the sake of an objective, masked by massive motivation that eventually becomes toxic and. The non-turning back point from which athletes develop overtraining syndrome occurs when conditioning processes and adaptations to sport become dysfunctional, which trigger multiple novel pathological pathways that start a process of self-destroying, that are extremely burdensome and effortful to overcome. At least one episode of overreaching has occurred in virtually all patients, and does not necessarily represent an alert sign when it occurs singly and is fully addressed. 

The recent lessons from the novel insights in overtraining syndrome allow to reframe overtraining syndrome from a simplistic understand of the triggers as being excessive training to a complex sum and web of interactions of dysfunctional changes that occur in response to a sum, respective intensities, and synergistic interactions between deprivations. Conversely, from the historical learning to the future perspectives, the comprehension that oversimplified attempts to explain the pathophysiology of overtraining syndrome will always be unsuccessful is key, since overtraining syndrome is the result of the exactly opposite: complex interactions that consequently lead to complex dysfunctions with a pitch of enigma.

The swell version of overtraining syndrome is the representation of the necessary improvements that need to be performed on the methodology and design of the research on the endocrinology of physical activity and sport, since inconsistent findings on hormonal responses in healthy athletes, as well as the lack of determination of sports-, sex-, age- and conditioning level-specific hormonal and metabolic findings prevented the disclosure of abnormalities in these respective systems in overtraining syndrome, once the basis for comparative analyses was undetermined. 

The book will introduce you to a completely novel, more comprehensive view on overtraining syndrome that moves from a training-centered  to an athlete-centered perspective. A practical approach that will help you understand, by a step-by-step explanation, uncomplicating this inherently complicated disease.

This book brings the scientific background to demonstrate that overtraining syndrome should not be assessed as a distinct disorder, and also proposes the concept of Paradoxical Decontioning Syndrome (PDS) as an expression that better reflects the central characteristic of overtraining syndrome.

In conclusion, this book goes beyond. Beyond the classical view on overtraining syndrome, which naturally encompasses a broader range of aspects. Beyond the classical and somewhat biased characterization of athletes suspected of overtraining syndrome. Beyond overtraining syndrome per se. And beyond the classical proposed mechanisms for OTS, since the growing understanding that overtraining is the end of a pathological process that comprises several other related conditions are making these deprivation-derived, LEA-generated and burnout-related dysfunctions progressively indistinguishable between them, while the specific location of the line that divides between physiological and pathological is becoming blurrier. 

We learned to respect the timing of training. Now we need to learn to respect our limits. And listen to them. 


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