Does Running High Mileage Make You More Prone to Illness?

I got a horrible cold a couple of weeks ago.  I say it was horrible, but it was probably only ordinary.  I just seem to never get sick--except a couple of times a year during my marathon training cycle.  I work at a preschool and wipe noses all day, but I only get one or two colds a year.  When I do get them, they are bad. I am weak and sleep a lot at the beginning, along with feeling a tickle in my nose that means the cold is on its way.  Next, I have a few nights of bad congestion and can't sleep.  I lose my voice for a couple of days as the dreaded drainage occurs.  Finally, I have a chest cough for a few more days.  All in all, it is over a week of some pretty miserable symptoms.

I decided to look on the internet for articles about how runners seem to get more infections when they are running higher mileage.  This article does support the claim that running high mileage makes you more susceptible to illness.  From the article, "Although moderate exercise may help protect athletes from sickness, training for too long at too high an intensity appears to make athletes more susceptible to illness.  Laboratory research shows that athletes exercising at a high intensity for 90 minutes or more experience a steep drop in immune function that can last up to 24 hours."

Maybe more concerning was an article I found trying to make a connection between runners and higher rates of cancer.  This article called "Can Too Many Miles Make You Sick?" presents the idea that running high mileage affects runners at the cellular level, even drawing a possible link to runners and cancer, though nothing has been proven yet.

I guess I am a little bothered by all of this, thinking that something I am doing to be more healthy could actually be making me more susceptible to being sick.  Colds are one thing, but cancer?  

It was during the week that I was sick with my cold that Dink Taylor, owner of Fleet Feet Sports and avid runner here in Huntsville, was hospitalized for what he later learned was a stroke.  If you know Dink, you know that he is the last person you would think this could happen to.  He is in excellent shape and runs all of the time.  I think it made many runners in our area stop and realize that, even though we are trying our hardest to be healthy and physically active, sometimes that is not enough.  We are not immune to things; we are not building a wall around ourselves from germs and cancer and strokes.  We are trying to be healthy, for ourselves and for our kids, we are trying to be an example to others, and we are doing something we enjoy all at the same time.  And sometimes that has to be enough.