Markers of excessive exercise

Can J Appl Physiol. 1999 Feb;24(1):66-73. doi: 10.1139/h99-007.


Overtraining is of serious concern to long-distance runners and will affect 65% of them at some time in their competitive career. The clinical presentation is nonspecific but the classical symptoms include fatigue, mood disturbances, frequent upper respiratory infections and injury, and a decrease in performance. Dysfunction of the hypothalamic pituitary axis from repeated stress, of a physical or nonphysical nature, represents the most likely pathogenesis of this condition. There is no single biological marker that is diagnostic of an overtrained state; however, several parameters deserve further study. The time to volitional fatigue on a cycle ergometer at an intensity of 110% of the individual anaerobic threshold represents a possible laboratory test. Salivary IgA holds promise as a useful immunoligical marker of the overtrained state and further research is needed to determine the validity of plasma glutamine as a blood marker. The most promising tool at present is a measure of the athlete's mood state, and several psychological tools can be used for this purpose.

Publication types

  • Review

MeSH terms

  • Athletic Injuries / physiopathology
  • Biomarkers*
  • Fatigue / physiopathology
  • Humans
  • Immune System / physiology
  • Mood Disorders / physiopathology
  • Physical Education and Training*
  • Respiratory Tract Infections / physiopathology
  • Running / physiology*
  • Running / psychology
  • Stress, Physiological / physiopathology


  • Biomarkers