I've unfortunately been battling a cold since the turn of the year and so have not been running since I didn't want to make things worse by pushing either distance or intensity while under the weather. However, this forced break has given me time to reflect on running and illness.
|© 2009 Doug Savage|
Certainly, my individual experience is not enough to account for anything substantive so I decided to do a little research and, after a quick scan of the literature, it seems that there definitely might be some weight to the theory. Weidner and Sevier (1996) find that
"...regular, rigorous exercise increases both the incidence and severity of upper respiratory illness, yet the immune system appears to have a distinct level at which moderate exercise promotes optimum health."Essentially, it boils down to this:
Certain levels of exercise = GOOD
Too much or too strenuous exercise = BAD
Well, not bad, per se... but too much or too strenuous activity could risk increasing one's chances of getting sick. So... still not good, really.
How to mitigate? Unfortunately, for long distance runners and high intensity athletes, there's not much else to do beyond what anyone can do: keep stress to a minimum, wash your hands and get enough sleep (Brown, 2013; Reynolds, 2009).
However, the literature does say that moderate exercise or less-than-normal-intensity exercise while ill is fine, so long as the symptoms are confined to "above the neck" i.e. just a head cold (Brown, 2013; Laskowski, 2014; Reynolds, 2009; Weidner & Sevier, 1996). But - caution! If you push things while still sick, you'll probably stay sick or even make things worse (Laskowski, 2014; Reynolds, 2009).
There you have it. Mystery solved: running can contribute to illness. Also, I'm not crazy; getting sick while running is a thing!
Final note: when trying to decide whether or not to run when sick, the basic rule of thumb is - as in most other things when running - "let your body be your guide" (Laskowski, 2014). It knows what's best.
Brown, J. (2013, March 11). How Exercise Affects Immunity. Athletes’ Performance. Retrieved from http://www.coreperformance.com/knowledge/wellness/how-exercise-affects-immunity.html
Laskowski, E.R. (2014, March 6). Is it OK to exercise if I have a cold? Mayo Foundation for Medical Education and Research (MFMER). Retrieved from http://www.mayoclinic.org/healthy-lifestyle/fitness/expert-answers/exercise/faq-20058494
Reynolds, G. (2009, October 14). Phys Ed: Does Exercise Boost Immunity? The New York Times. Retrieved from http://well.blogs.nytimes.com/2009/10/14/phys-ed-does-exercise-boost-immunity/?_r=1
Weidner, T. G., &; Sevier, T. L. (1996). Sport, Exercise, and the Common Cold. Journal of Athletic Training, 31(2), 154–159. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1318446/pdf/jathtrain00018-0060.pdf