Home > Uncategorized > Galen Rupp’s revenge: allergies in marathon runners

Galen Rupp’s revenge: allergies in marathon runners

December 1st, 2011

It’s pretty well established that heavy training — the type you might do to prepare for a marathon — can reduce immune function a bit, leaving you more susceptible to colds. Same thing with the race itself, which can trigger a temporary lowering of immune function: it’s well documented that runners have an elevated risk of catching an upper respiratory tract infection (URTI) in the week or so after a marathon.

Except… are those symptoms (e.g. congestion, cough, watery eyes, sneezing, “nasal discharge”) really the result of URTIs? In a new paper in Medicine & Science in Sports & Exercise, a group of mostly British researchers suggest an alternate explanation: allergies. And they provide some intriguing data to support this claim. They studied 208 runners who ran the 2010 London marathon. Before the race, the runners completed an allergy questionnaire and did a blood test to look for reactions to common inhaled allergens (like pollen). After the race, they filled out questionnaires daily for 15 days describing any possible URTI/allergy symptoms. The key results:

  • 47% of the runners suffered from the symptoms of an apparent URTI after the marathon (i.e. they reported symptoms on at least two days in a three-day period during the 15-day follow-up).
  • The researchers also surveyed non-runners who were living with the runners in the study; only 19% of the non-runners reported URTI symptoms during the period, which (the researchers say) argues against the symptoms being due to an infectious disease like cold or flu.
  • 40% of the runners had some form of allergy, based on either the questionnaire or blood test — and the allergy questionnaire was a “significant predictor” of the whether the runner would suffer URTI symptoms after the race.

So what’s going on here? According to the researchers:

The shifting of breathing during exercise from nose to combined mouth and nasal breathing results in a greater deposition of airborne allergens, and unconditioned air, to the lower airways.

They go on to note that these symptoms may be associated with asthma, but that, “worryingly,” few of the runners were being treated pharmacologically for asthma — which they attribute to the fact that asthma meds are restricted by the World Anti-Doping Association. Given that the average finishing time of their subjects was slower than five hours, I find this an extremely strange argument to make! They go on to recommend that recreational runners should be screened for allergies and consider treatment.

I think this is a really interesting topic. It’s been known for a long time that endurance athletes (particularly winter athletes) are far more likely to suffer from conditions like exercise-induced brochoconstriction (basically exercise-induced asthma symptoms) than the general population. Why is this happening? What makes athletes’ airways more sensitive? Is it the airways being dried out by large volumes of air passing through? Is it particulate matter being inhaled and damaging airways? Or is it allergens that are causing inflammation due to all the deep breathing? It would be great to see more research looking into these questions.

That being said, I think this study has some pretty important limitations. I found the presentation of the data to be a bit lacking — it’s very hard to get a precise sense of just how different the allergy and non-allergy groups were, to see how strong the data really is. But the more fundamental issue is simple: selection bias. The subjects “were recruited randomly during the 4-day registration exhibition before competing in the 2010 London Marathon.” So which people would be more likely to agree to fill out a questionnaire about allergies and give a blood sample for allergy testing? Probably people who have, or believe they have, allergies. So when the results tell us that a very high proportion of runners have some indication of allergies, that doesn’t necessarily hold true for all runners!

Still, a thought-provoking paper: maybe the famous “post-marathon cold” isn’t quite what we thought.

  1. John
    December 4th, 2011 at 01:41 | #1

    This reminds me of a few years ago at the age of 45 I’d try to get under 6 mins in the mile again at summer all-comers meets here in the Sacramento area. The meets were held at a all weather track venue, but a Field Turf infield. It was hot and it smelled like tires. For a few days after the meet, my throat would burn. At first I thought it may be ozone but the air quality for those days, in that area were low. I researched a bit at the time but precious little exists on air quality studies associated with Field Turf on hot days. Any recent studies? Thanks

  2. Bman
    December 4th, 2011 at 02:14 | #2

    @alex – 2 notes:
    1. Albuterol (salbuterol) is no longer restricted by WADA if taken as an inhalation (at least for swimming… I assume for running as well). Also, drugs like Singulair are not prohibited by WADA either.
    2. I doubt the airways are being dried out as swimmers, even in winter, breathe in very humid air and tend to be very susceptible to URTIs.

    I personally doubt allergies, even asthma. I have had asthma (which, surprisingly, is going away the past few years). It is not the same. I have also gotten many, many URTIs, and they go away. Though asthma can go away over the course of years, it is not likely to come and go so fast (and as I said, the symptoms are not the same).

  3. chuck
    December 6th, 2011 at 15:09 | #3

    is it possible marathon runners eat a lot of food that can cause a hystamine response?

  4. Bman
    December 6th, 2011 at 20:00 | #4

    @chuck – that’s an interesting thought. my first thought was no, as it seems so directly linked to bouts of really hard training. but then i realized that during really hard training calorie consumption goes up dramatically, and the composition of the diet also tends to change (with a higher percentage of carbs).

    i am still sure that the harder training, in combination with the immune system suppression that goes along with getting really beat up from the hard training, must at least be a set up for the URTIs. if food is involved, it likely is only because the compromised immune system is not working properly.

  1. December 2nd, 2011 at 14:10 | #1
  2. December 20th, 2011 at 19:05 | #2