Can Exercise Make You Sick?

Created by: Pete Shuster on

Impact of Excessive Exercise on Immune System

A common perception exists that overtraining will cause athletes to become ill. In fact, results from a survey conducted by the Gatorade Sports Science Institute show that nearly 90 percent of 2,700 high school and collegiate coaches and athletic trainers believe that overtraining can compromise the immune system and make athletes sick.

There is a term to associated with the question: can exercise that can make you sick?  It is called overtraining syndrome (OTS). Symptoms include:

  • Decreased athletic performance
  • Fatigue
  • Elevated heart rate
  • Muscle and joint pain
  • Blood pressure changes
  • Sleep disturbances with or without night sweats
  • Loss of appetite
  • Thirst
  • Increased susceptibility to and severity of illness, colds, and allergies
  • Flu-like symptoms
  • Swollen glands
  • Gastrointestinal disturbances
  • Depression
  • General apathy
  • Irritability
  • Inability to concentrate
  • Decreased libido
  • Increased sensitivity to environmental and emotional stress

Febbraio et al. in American Journal of Physiology - Cell Physiology. Published 1 April 2001: Vol.280 no.4 concluded: "Neuroendocrine hormones have been shown to regulate the immune response, and direct neuroimmune communication occurs . Proinflammatory cytokines activate both the hypothalamic-pituitary-adrenal axis and the sympathoadrenergic system, both of which exert potent anti-inflammatory actions that limit production of proinflammatory cytokines. Incubation of whole blood with epinephrine or norepinephrine decreases IL-6 and TNF-α production. Furthermore, administration of cortisol at levels comparable to those in the present study decreased LPS-stimulated IL-1, TNF-α, and IL-6 production. In the present study, cells spontaneously producing IL-1α and IL-6 ceased production after exercise, and the amount of TNF-α produced by each cell was reduced postexercise. In addition, cells produced less cytokine upon stimulation postexercise. Because there was an increase in the concentration of plasma epinephrine, norepinephrine, and cortisol postexercise, it is possible that these hormones had a role to play in decreasing cytokine production."

Your immune system, when healthy, works in a prefect harmony of signaling and feedback loops. When dysregulated by OTS, it can make you sick. When designing or making changes to your exercise program, be safe and be well.