Overtraining Syndrome in Athletes: A Comprehensive Review and Novel Perspectives

346 Pages·2020·15.207 MB·English

by  Flavio Cadegiani

Overtraining
Syndrome in Athletes
A Comprehensive Review
and Novel Perspectives
Flavio Cadegiani
123
Overtraining Syndrome in Athletes
Flavio Cadegiani
Overtraining Syndrome
in Athletes
A Comprehensive Review and Novel
Perspectives
Flavio Cadegiani
Federal University of São Paulo
São Paulo
São Paulo
Brazil
ISBN 978-3-030-52627-6 ISBN 978-3-030-52628-3 (eBook)
https://doi.org/10.1007/978-3-030-52628-3
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To my mom, Ana Dorinda, who always
supported me.
To my dad, Flavio, for his unique way
of loving.
To my stepdad, Weber; stepmom, Mara; sister,
Pietra; my maternal grandparents, Maria del
Carmen and Mariano; and paternal
grandparents, Alice and Pietro, in memoriam.
To the athletes that participated in the EROS
study, who opened the doors to a new era in
understanding overtraining syndrome.
To the non-athletes that participated in the
EROS study, who opened the doors to the
cognizance of endocrinology and metabolism
in the healthy athlete.
To Prof. Dr. Claudio Kater, my PhD guide
and tutor forever, who supported me wherever
I wanted to go, providing me the most expert
opinions, and who has become the reference
of my professional and scientific life.
To my colleagues from the PhD program in
Clinical Endocrinology at the Adrenal and
Hypertension Unit, Department of Medicine,
Federal University of São Paulo, Brazil.
To all editors who gave me the chance to
publish my work, opening the doors to
the world.
To all reviewers who gave me true lessons
and guidance to never stop improving the
quality of what I publish.
To the team at my private clinic, who helped
me make last-minute changes and supported
me with all my non-professional tasks when I
was too busy researching and writing
this book.
To all my patients, who showed me how to
constantly improve my medical practice, and
who opened my eyes to the gaps in the
understanding of impaired athletes and
overtraining syndrome.
To all those who had no idea of what I was
writing—and may still not understand—but
encouraged me in this endeavor.
To my giant cats, Ken and Barbie, who
jumped on my hands while I was writing the
book and gave me their unconditional love
throughout this journey.
Preface
Overtraining syndrome is among the diseases with the largest prevalence in elite
athletes, but not limited to this group.
Its occurrence was first hypothesized when athletes began to present unexplained
decrease in 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 rise due to recommencement of the Olympics after the World War II (WWII)
and the Cold War, when performance in sports had unprecedented political weight.
Some athletes started to show a progressive loss of performance that responded
paradoxically to increase of training load, that is, the more they trained, the worse
they performed, and were unresponsive to recovery interventions.
This new paradox observed in some athletes was unsuccessfully investigated for
an extensive range of causes could also justify the underperformance.
A syndrome of unexplained underperformance in athletes then emerged, which
was strictly related to excessive training. Hence, the term overtraining syndrome was
intuitively coined, although only decades after the first descriptions of overtraining.
Once excessive training was assumed to be the sole trigger of overtraining syn-
drome, changes in training patterns towards periodization, avoiding excessive train-
ing, was expected to mitigate this syndrome. However, periodization of training
sessions as the only intervention unexpectedly failed to reduce the incidence over-
training syndrome. Indeed, looking backward, the identification of excessive train-
ing as the intrinsic factor that leads to loss of performance, as well as the underlying
mechanisms to justify reduction of physical capacity in response to over-exercising,
were not elucidated by that time, and the hypothesis that overtraining syndrome was
actually caused by overtraining was merely empirical.
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. End result, a gap in the knowledge of what really trig-
gered overtraining syndrome remained unsolved.
While the majority of elite athletes experience at least one episode of overtrain-
ing syndrome, the growing number of non-professional athletes that practiced sports
at extremely intense levels, resembling professionals, with concurrent rigid
vii
viii Preface
practices and living patterns, led to an increase of overtraining syndrome inci-
dence—and recognition.
The use of the term overtraining has spread among athletes, sports coaches, and
more recently in specific and general media. However, almost always this expres-
sion was used to describe conditions other than overtraining syndrome, while
unsubstantiated characteristics and manifestations alleged to be part of overtraining
syndrome that 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,
have become secondary in the context of the broad use of the term overtraining.
With general misuse of the term overtraining, the loss of significance of over-
training syndrome, and the reduction in scientific publishing on the field in the
1990s, those suffering from this condition remained underappreciated, which ended
the career of several professional athletes.
Fortunately, interest in this syndrome 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 of its actual characteristics, and the unexpected decrease of sports perfor-
mance has become central again.
However, unanswered questions regarding overtraining syndrome pathophysiol-
ogy, triggers, mechanisms, and effects, which have only been partially addressed by
classical theories, still prevailed.
In this context, several novel studies have recently had the opportunity to revisit
overtraining syndrome from a more comprehensive perspective, which comprised
wide, different aspects to be potentially correlated with the development of the syn-
drome, and did not limit the occurrence of overtraining syndrome to training
patterns.
Consequently, multiple novel findings have been unveiled, which provided
embodiment for novel insights and novel concepts that have 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 showed that overtraining syndrome resulted from
sum, respective intensity, and interactions between a combination of chronic depri-
vations and excessive efforts, including relatively insufficient caloric and protein
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 dysfunc-
tional (“maladaptations”), resulting in multiple hormonal, metabolic, immunologic,
inflammatory, and muscular abnormalities, which eventually lead to the main mani-
festations of overtraining syndrome, including mental and physical exhaustion,
pathological muscle soreness, loss of multiple abilities in physical performance,
Preface ix
increased predisposition to overall infections, and burnout-like signs and symp-
toms. 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 charac-
teristics is not limited to its intrinsic features. In a bigger picture, overtraining syn-
drome is highly representative of an ample and diverse range of aspects.
Overtraining syndrome is the representative dysfunction resulting from a society
that increasingly worships high performance in major aspects of life simultane-
ously—physical, intellectual, social financial, professional, sexual, and psychologi-
cally, 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 clus-
ter of diseases derived from multiple deprivations—deprivation of food, sleep, rest,
and indulgences—that generate a state of low energy availability (LEA) and conse-
quent chronic energy deprivation, which eventually induces a decrease of sports
performance and shares multiple similarities with burnout syndrome. These condi-
tions comprise the female athlete triad and its expanded concept of relative energy
availability of the sport (RED-S), the burnout syndrome of the athlete, and pseudoo-
vertraining and overtraining-like states.
Collectively, the multiple similarities allow to hypothesize that all these dysfunc-
tions may be different poles of a same, broader condition, which has been termed as
the “impaired athlete” although extensive research is needed to confirm this hypoth-
esis. Indeed, if athletes diagnosed with the female athlete triad or relative energy
availability of the sport 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 patho-
logical anthropological context that considers strict eating as a quality to be wor-
shiped, with an implicit sense of superiority of those that can fully control their
dietary patterns. From a societal perspective, the more implicit and camouflaged
version of eating behavior 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 decreased perfor-
mance as the final result of dysfunctional adaptive processes, which may also occur
under states that are not necessarily labeled as a specific diagnosis.
Despite the description of burnout syndrome of an athlete as a distinct condition,
overtraining syndrome better represents the model of burnout syndrome in athletes,
x Preface
in particular regarding the lack of simple, frank, and ubiquitous markers or mecha-
nisms that explain the challenges to perform a correct diagnosis and the high indi-
viduality 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.
From a comprehensive perspective, overtraining syndrome represents the com-
plexity of when 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 syn-
dromes can be extended to the 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
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 these parameters underwent in this popu-
lation of athletes. Perhaps, its complexity associated with several types of “unex-
plained complaints,” including those in joints and muscles, has 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), represent the continuum that this syndrome
undergoes before its end-stage and demonstrates that overtraining syndrome results
from persistent ignoring of the warning signs that occur through repeated episodes
of overreaching, for the sake of an objective, masked by massive motivation that
eventually becomes toxic. The point of no return, after which athletes develop over-
training syndrome, is reached when conditioning processes and adaptations to sport
become dysfunctional, triggering multiple novel pathological pathways that start a
process of self-destruction which is extremely burdensome and effortful to over-
come. 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 understanding 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 inter-
actions between deprivations. Conversely, from historical lessons to future perspec-
tives, the comprehension that oversimplified attempts to explain the pathophysiology
of overtraining syndrome will always be unsuccessful is key, since overtraining
syndrome is a result of the exact opposite: complex interactions that consequently
lead to complex dysfunctions with a pitch of enigma.