Monday, February 15, 2010

Dangerous Exercise

Dangerous exercise: lessons learned from dysregulated inflammatory responses
to physical activity

Dan Michael Cooper, Shlomit Radom-Aizik, Christina Schwindt, and Frank
Zaldivar, Jr.

J Appl Physiol 103: 700-709, 2007.
First published May 10, 2007;

Pediatric Exercise Research Center, Department of Pediatrics, University of
California, Irvine, California

Exercise elicits an immunological "danger" type of stress and inflammatory
response that, on occasion, becomes dysregulated and detrimental to health.
Examples include anaphylaxis, exercise-induced asthma, overuse syndromes,
and exacerbation of intercurrent illnesses. In dangerous exercise, the
normal balance between pro- and anti-inflammatory responses is upset. A
possible pathophysiological mechanism is characterized by the concept of
exercise modulation of previously activated leukocytes. In this model,
circulating leukocytes are rendered more responsive than normal to the
immune stimulus of exercise. For example, in the case of exercise
anaphylaxis, food-sensitized immune cells may be relatively innocuous until
they are redistributed during exercise from gut-associated circulatory
depots, like the spleen, into the central circulation. In the case of
asthma, the prior activation of leukocytes may be the result of genetic or
environmental factors. In the case of overuse syndromes, the normally
short-lived neutrophil may, because of acidosis and hypoxia, inhibit
apoptosis and play a role in prolongation of inflammation rather than
healing. Dangerous exercise demonstrates that the stress/inflammatory
response caused by physical activity is robust and sufficiently powerful,
perhaps, to alter subsequent responses. These longer term effects may occur
through as yet unexplored mechanisms of immune "tolerance" and/or by a
training-associated reduction in the innate immune response to brief
exercise. A better understanding of sometimes failed homeostatic
physiological systems can lead to new insights with significant implication
for clinical translation.

inflammation; innate immunity; leukocyte; asthma


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[Tom: Somebody summarised this to me with the following "take-home" points:
- exercise is a major stimulus of the immune system
- very little research done on exercise in chronic inflammatory states (p.
705) (which CFS likely has some components of)]


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