Dangerous exercise: lessons learned from dysregulated inflammatory responses to physical activity, 2007, Dan Michael Copper et al

Abstract
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.

Dangerous Exercise
The usual balance between the pro- and anti-inflammatory exercise responses is occasionally upset, however, and when it is, disease may result. In the following, we review several examples of failed homeostatic inflammatory responses to exercise.
LINK

 

What is clear from the existence of dangerous exercise is that the immune responses caused by exercise are real and robust. Like pharmaceutical therapies, prescribing exercise as therapy, an activity that is gaining in acceptance throughout the medical community, must be predicated on understanding the risks and benefits of exercise as thoroughly as possible. Only in this manner can the “right” dose be achieved. Finally, a greater understanding of dangerous exercise is likely to yield new knowledge that is useful not only in the context of exercise physiology but also in shedding new light on the role of the immune system as it adjusts to daily life perturbations such as physical activity.

 

For what it is worth, I sent posted this e-letter on the journal site back in 2010. Unfortunately I think the journal got rid of the e-letter facility at some stage but it’s available here:
https://pubpeer.com/publications/BF94AFF65C364FAE33466B0FB15A22

This is a paper I’ve cited in some of my publications.

 

Any therapy that is shown to be helpful for normal, generally healthy individuals can be harmful to those with abnormalities. Doctors should be trained to be aware of and accepting of such abnormalities. We're not all identical clones of the subjects in whatever study tested the therapy.

 

Exercise can be dangerous but I am not sure this is a particularly good paper to illustrate the point. The stuff in the abstract is mostly wrong or the sort of speculation you would expect from someone who doesn't know much immunology. It comes from a unit devoted to exercise. It doesn't make the simpler point that exercise is good for healthy people to keep healthy but not for ill people and there probably shouldn't be any exercise medicine units.

 

Reminds me of reports decades ago about long distance women runners who become too thin via not replacing calories lost in exercise, and stopped menstruating and if prolonged, lose bone mass, among other things.