By Corrine Malcolm,
CTS Ultrarunning Coach
You’re right, you’re not going to “freeze your lungs”… however, exercising and competing in extreme environmental conditions can have a long lasting negative impact on your lung health. Every winter runners flood my social media feed covered in various forms of human icicles, temperatures flash across the screen “0F” “-16F” “-36F”, wind chills dropping the skin temperature lower. Every winter I cringe and have to ask, “at what cost?” Is there a specific purpose to be gained, aside from “proving your own toughness”, by slogging out the miles as temperatures dip below zero?
Of course, you may live in a cold, wintery place. I myself grew up in Northern Wisconsin and routinely had school canceled growing up when the temperatures would dip, almost every February, to -35F. Growing up as a cross-country skier, winter and cold were an unavoidable part of my childhood. In college I studied exercise and environmental physiology and watched my teammates struggle with “skiers’ cough”, which for some turned into what we thought at the time was asthma. I began to wonder, what does happen to our lungs as we train and race over time? The answer is an increased risk for developing a hyper-reactive airway, or what is now called exercise induced bronchospasm (EIB), what was originally called exercised induced asthma.
Exercise Induced Bronchospasm
I like to think of EIB as an overuse injury of the lungs. The cells that line your lungs are incredible, and they have an amazing capacity to repair themselves quickly. However, this repeated injury-repair cycle is responsible for adaption and structural change that is not always positive. When you exercise your ventilation rate increases, and when combined with another variable like cold and/or dry air (note that the issue with extremely cold air is that it is extremely dry), you cause water to evaporate from the airway surface liquid that makes up the lining of your bronchioles at a rate your body cannot keep up with. This drying causes a shift in the osmotic gradient, or the movement of liquid, of the cells lining your airway, which stimulates the release of inflammatory mediators. These inflammatory mediators, like histamine, can influence the smooth muscles of the bronchioles, causing constriction, mucus build-up, and edema (swelling) (1).
Now, this is a slow and progressive problem. One day of running in extreme cold does not guarantee a lifetime of breathing issues. However, continued training in extreme environments does heighten your risk. There are certainly factors that may predispose you for developing EIB, including; high intensity activities, history of asthma, allergies, a history of atopy (or being hyperallergric, and allergic rhinitis (an allergic reaction to airborne allergens) (5). Additionally, the environmental conditions you regularly train and race in are known risk factors, including cold air, dry air, high pollen counts, pollution, insecticides, fertilizers, wildfire smoke, chlorination, car exhaust, etc (5).
Risks Over Time
As I mentioned above, this airway inflammation and airway limitation appear to progressively worsen over a season and over a lifetime in many endurance athletes, with 90% of the asthmatic population and 20% of the general population reportedly developing EIB (1,2, 5). You might be thinking to yourself, so that one time run is probably okay, and honestly you might be right. However, what we gathered in the lab on skiers was that even after a single week of training or racing in single digit temperatures all of the skiers in the study suffered a varying decrease in measures of expiratory volume (amount of air you can forcefully exhale), which could translate to a decrease in performance.
That’s right, if not for your general health, do it for your performance. The demands we place on our pulmonary system as endurance athletes is immense, sometimes so much so that we exceed the capacity of that system. The repeated drying of your airway surfaces over time can cause a thickening of those membranes (2). This causes a reduction in our ability to combat the evaporation of the liquid surface of our airways (1) so that your airways become more sensitive to irritants over time. This makes EIB progressive in nature, and ultimately leads to a ventilatory limitation during performance as a result of those permanent airway-structure changes due to frequent environmental exposure (3,4).
Protecting Your Lungs
So what can you do to protect your lungs? As my yoga teacher told me this past fall as the Bay Area was inundated by smoke from forest fires just north of us, “It’s a time to listen to your body, not your ego.”
Move your intervals inside.
If you can avoid doing intervals outside when the temperatures dip into the single digits, do so. It’s not so much the running that is the issue but the increased breathing rate during intervals that can cause the problem. It’s for that very reasons that the international ski federations do not allow races to take place if temperatures are below -4F to try to limit exposure of the athletes. Think of this as improving the quality of the work you are able to do.
Invest in a mask.
A Buff will not do. A Buff is great at protecting your skin from cold air, wind, and sun exposure. What it cannot do is effectively warm the air you are inhaling. There are relatively affordable masks designed exactly for the purpose of training and racing in extreme cold. AirTrim, made popular by Scandinavian skiers, is a great product.
Shorten the total duration.
Part of the lung equation is a combination of how hard you are working and how long you are working. Along with moving the hard work inside when the temperatures dip below zero, think about shortening your total workout length. Cold exposure is harder on your body metabolically (you have to stay warm after all) and so your typical run will have a higher stress load on your system.
Corrine Malcolm has a B.S. in Health and Human Performance, and she is a Masters candidate in Biomedical Physiology. In 2016, she won the USATF 50 Mile Trail Championships and represented the US at IAU Trail Running World Championships. It is her passion to combine two of her loves, science and sport, as a coach for CTS.
- Rundell, K., & Jenkinson, D. (2002). Exercise-induced Bronchospasm in the Elite Athlete. Sports Medicine, 583-600.
- Kippelen, P., Fitch, K., Anderson, S., Bougault, V., Boulet, L., Rundell, K., Malcolm, S., & Mckenzie, D. (2012). Respiratory health of elite athletes- preventing airway injury: A critical review. British Journal of Sports Medicine, 471-476.
- Sheel, A., Macnutt, M., & Querido, J. (2010). The pulmonary system during exercise in hypoxia and the cold. Experimental Physiology, 422-430.
- Boulet, L. (2012). Cough and upper airway disorders in elite athletes a critical review. British Journal of Sports Medicine, 46(4), 417-21.
- Molis, M. A., & Molis, W. E. (2010). Exercise-Induced Bronchospasm.Sports Health: A Multidisciplinary Approach,2(4), 311-317. doi:10.1177/1941738110373735