Long-Distance Running: Nothing to Sneeze At?

Posted by Filed Under: Health & Fitness, Science and Research

in the knowThere was an intriguing article in The New York Times recently about a study that had found a direct correlation between marathon training and an increased risk of skin cancer. The basic conclusion here is hardly surprising: Marathon runners spend a lot of time outdoors, often squeezing in runs during lunch in the peak sunlight hours, hence they’re more susceptible to melanoma. Fair enough.

But buried farther down in the story was a remark by one of the study’s authors that struck a false note with me.

Sun exposure may not be the only risk factor that distance runners face. The authors write that although there is no question that regular exercise is important to good health, there is good evidence that high-intensity training and excessive exercise can lead to suppressed immune function.

“This is quite well established,” Dr. Cristina M. Ambros-Rudolph said. “Many alterations in immune cell function have been noted at the cellular level in marathon runners. For example, there is the association between excessive exercise and immunosuppression reflected in the increased incidence and severity of upper respiratory tract infections in marathon runners after races.”

Now, I’m no doctor, but I can say that my own training experience and that of the folks I train with on a regular basis is exactly the opposite of what Ambros-Rudolph says is established science. Since I began running seriously about six years ago, I can count on one hand the number of times I’ve gotten the flu or a cold or anything more serious than a runny nose. The one time I did get the flu was the direct result of a flu shot, but I’ll even count that just to be a good sport.

I live in New England, where winter can last a solid five months, spring is a rumor and we get paid off for all of that fun with Julys and Augusts that rival anything you’ll find in Virginia or the Carolinas. So I’m not exactly training in a hyperbaric chamber here. And yet, neither I nor 99 percent of the guys I train with get sick on a regular basis. This is despite the fact that most of us have kids who at this time of year are little walking Petri dishes, sneezing, wheezing germ factories on legs.

Why this is, I’m not really sure. But my best guess is that as runners most of us lead very active lifestyles, maintain healthier diets than most of the U.S. population and are generally very health-conscious. We pop multivitamins, gulp down glucosamine and chondroitin and drink water by the gallon. All of which probably helps keep our immune systems humming.

But perhaps the good doctor wasn’t talking about us average folk. Note her characterization of marathon training as “excessive exercise.” (Clearly she’s been talking to my wife.) She may well be referring to elite athletes who log 100-plus miles a week on a regular basis. By even our liberal definitions, that probably qualifies as excessive. Still, I’d be willing to bet dollars to doughnuts that a rigorous study of say 100 or even 50 regular runners would produce results that are more in line with my experience than the doctor’s assumptions.

I’m just sayin’.

About Dennis Fisher

Dennis is an award-winning journalist and not-so-award-winning runner. His day job involves writing about technology, which is why he runs so much. A native of Virginia, Dennis is a veteran marathoner and road racer who has recently discovered the joy and broken bones of trail running. He trains with the Greater Boston Track Club and lives outside Boston with his wife and children.

  1. Joe Ely on December 12th at 3:38 pm

    Dennis and others at CRN:

    Wouldn’t this be an interesting “scientific” project for CRN this winter? I’m thinking out loud here…

    a. Post a list for runners to sign up to report illness or lack thereof between now and April 1.

    b. Send an email each week for them to report illness and # of miles logged.

    c. See what you find by April.

    d. If there is a grad student out there or even an undergrad looking for a project…this could be fun to do.

    Just thinking, as I look out my window, see drizzle and chill for the next few days here in N Indiana and getting antsy to go run!!

  2. Dennis on December 12th at 9:00 pm

    I like that idea a lot. I’m not sure the results would hold up to peer review in the medical journals, but I think they’d be really interesting. I’m up for it.

  3. Kilo on December 13th at 8:21 pm

    Since I started running a few years ago, I’ve noticed that a long run will stop a cold dead in its tracks for me. I get a sore throat or a stuffy head, I go run for an hour or so, and the impending cold is gone. I’ve even forgotten about that healing trick, gotten sick, suffered 3 or 4 days, then (tired of lying around) I gone for a long run and come home completely cured. It amazed me at first, and now it’s happened so many times that I am a firm believer that it works. I seem to be very susceptible to colds to begin with but the running keeps them from developing. Anyone else experience this? Short runs don’t help; it has to be at least an hour for me.

  4. Rob on December 15th at 11:58 am

    The immunosuppressive effect of hard training and racing is well described in the scientific literature. Ten seconds search at Pubmed got me a nice page full of citations. The top one was this, which largely supports your intuition:

    Malm. C. (2006) Susceptibility to infections in elite athletes: the S-curve. Scand J Med Sci Sports. 2006 Feb;16(1):4-6.

    The susceptibility to upper respiratory tract infections (URTIs) after physical exercise has been described with a J-shaped curve, suggesting protection from infections with moderate exercise and increased risk for URTI’s in elite athletes. Several factors such as time of inoculation, previous infections, pathogen exposure, other stressors than exercise etc. can influence infection outcome. Observed infections in athletes can, therefore, be either the result of increased susceptibility to a novel pathogen, or more severe symptoms of an already established infection. Moreover, the definitions of “strenuous” exercise and “elite” athletes are equivocal, making comparisons between studies difficult. Because absence of infections is inevitable to become and maintain status as an elite athlete, it is suggested that there is an S-shaped relationship between exercise load and risk of infections. To become an elite athlete one has to possess state-of-the-art physique, including an immune system able to withstand infections even during severe physiological and psychological stress.