Training modalities: over-reaching and over-training in athletes, including a study of the role of hormones

Best Pract Res Clin Endocrinol Metab. 2003 Jun;17(2):191-209. doi: 10.1016/s1521-690x(02)00104-5.


Background: An imbalance between the overall strain experienced during exercise training and the athlete's tolerance of such an effort may induce over-reaching (OR) or over-training syndrome (OTS). OR is characterized by an unexpected drop in performance despite increased training load or may lead to OTS, a complex state of exhaustion and persistent fatigue.

Aim: As it is important to adapt training modalities to the athletes' needs, and as there is still a lack of objective parameters suitable for the prevention and diagnosis of OTS, we studied 11 male elite cyclists, analysing the impact of training modalities ('training high-living low'; 'training low-living low') on exercise performance as well as on variable hormonal responses in order to detect early and sensitive markers for OR and/or OTS.

Results: Although the variable hormones varied quite substantially among the two training groups, two ratios--free testosterone/cortisol (FTCR) and insulin-like growth factor-I/cortisol (IGF-I/C)--did not differ at all. This is important because athletes' final aim is to improve in an anabolic way. In addition, IGF-binding protein 3 (IGF-BP3) might be a useful screening factor for OR and OTS.

Conclusion: First, from a critical review of the existing over-training research, it must be concluded that there has been little improvement in recent years in the tools available for the diagnosis of OTS. Second, as variable training modalities do have a major impact on isolated hormones in circulation, hormonal ratios such as FTCR and IGF-I/C have to be calculated. These ratios might be useful parameters in the early detection of a imbalance between anabolic and catabolic metabolism.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Altitude
  • Bicycling / physiology
  • Biomarkers
  • Hormones / blood
  • Hormones / physiology*
  • Humans
  • Hypoxia / physiopathology
  • Physical Fitness / physiology*


  • Biomarkers
  • Hormones