Flavio Cadegiani - Overtraining Syndrome in Athletes: A Comprehensive Review and Novel Perspectives

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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 syndrome, changes in training patterns towards periodization, avoiding excessive training, was expected to mitigate this syndrome. However, periodization of training sessions as the only intervention unexpectedly failed to reduce the incidence overtraining syndrome. Indeed, looking backward, the identification of excessive training 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 triggered overtraining syndrome remained unsolved.

While the majority of elite athletes experience at least one episode of overtraining syndrome, the growing number of non-professional athletes that practiced sports at extremely intense levels, resembling professionals, with concurrent rigid practices and living patterns, led to an increase of overtraining syndrome incidenceand 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 expression 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 overtraining 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.