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Novel insights of overtraining syndrome discovered from the EROS study
  1. Flavio A Cadegiani,
  2. Claudio Elias Kater
  1. Endocrinology, Universidade Federal de Sao Paulo, Sao Paulo, Brazil
  1. Correspondence to Dr Flavio A Cadegiani; superendocrinology{at}


Background Excessive training and inadequate recovery could cause ‘overtraining syndrome’ (OTS), which is characterised by underperformance and fatigue. The pathophysiology of OTS is unclear. We aimed to describe novel mechanisms and risk factors associated with OTS, and thereby facilitate its early identification and prevention, from a comprehensive joint qualitative analysis of the findings from all the four arms of the Endocrine and Metabolic Responses on Overtraining Syndrome (EROS) study.

Methods We compared the types and proportions of behavioural patterns of 67 evaluated parameters of OTS from 51 participants—athletes with OTS (OTS, n=14), healthy athletes (n=25) and healthy non-physically active controls (n=12). We performed overall and pairwise comparisons for statistically significant differences between the three groups (p<0.05).

Results A total of 44 (65.7%) markers exhibited significant differences between the three groups: 32 (72.7%) showed a loss of the conditioning effect of exercise (‘deconditioning’), 7 (15.9%) showed changes exclusive to OTS, 3 (6.8%) maintained the exercise-induced conditioning effects and 2 (4.5%) revealed an exacerbation of the adaptive changes to exercises.

Conclusion Our findings suggest that OTS is likely triggered by multiple factors, not restricted to excessive training, resulted from a chronic energy deprivation, leading to multiple losses in the conditioning processes typically observed in healthy athletes, as a combination of ‘paradoxical deconditioning’ processes, which explains the gradual and marked loss of physical conditioning found in OTS. We, therefore, suggest that the term ‘paradoxical deconditioning syndrome’ better represents the features of this syndrome.

  • fatigue
  • sports performance
  • sports endocrinology
  • hormones
  • paradoxical deconditioning syndrome
  • overtraining syndrome

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  • Presented at The results of the study are presented clearly, honestly and without fabrication, falsification or inappropriate data manipulation. Raw data can be obtained from the repository mentioned in the study.

  • Contributors FAC and CEK developed the central idea of the present manuscript. FAC performed the tests of the EROS study, compilated the data, analysed the results and participated in the discussions. CEK actively participated in the discussion, supervised and reviewed the results, helped with the final version of the manuscript and gave the last word before the submission.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Disclaimer No funding was provided for the study, as the materials were directly provided by: (1) DASA Diagnostics (São Paulo, SP, and Brasília, DF, Brazil), (2) Federal University of São Paulo (São Paulo, SP, Brazil) and (3) Corpometria Institute (Brasília, DF, Brazil).

  • Competing interests The results of the present study do not constitute an endorsement by ACSM. The authors declare no competing interests, including no professional relationships with companies or manufacturers who will benefit from the results of the present study. We did not directly involve patient and public (PPI) in this study, but the database used in the study was developed together with PPI, and a personalised feedback was given based on participant's expectations.

  • Patient consent for publication Not required.

  • Ethics approval The study was approved by the ethical committee of the Federal University of São Paulo (approval number: 1093965).

  • Provenance and peer review Not commissioned; externally peer reviewed.