As an (ex) XC runner who has done thousands of miles in the cold and snow, the word "normally" in that article's pivotal sentence, "This can cause the smooth muscle in the airway to narrow, reducing the athletes’ ability to breathe normally" is a bit of a stretch. It's like saying these athletes all have "exercise-induced tachycardia" because their heart rate goes up when they compete. Responding to dry, cold air with narrowed airways is normal. I don't dispute that some respond to it worse than others and need medication to come back to the default response, but it's easy to stretch that diagnosis and take salbutamol until you're
better than the baseline.
My lungs are currently in the annual process of acclimating to the newly cold fall air. Every year for decades I've been running in October and there are a couple weeks when the temperature crashes from the last encore of summer at 60F/15C seemingly overnight to frosty mornings and 40F/5C runs and the leaves change. I can feel that my legs are fine but I'm breathing harder than usual, and I can literally see on my Garmin that my average pace has decreased but my heart rate is unchanged or elevated. By November my VO2 max will be up a bit and my pace will be mostly back to normal.
Does it feel like I'm breathing through a slimy straw on those first frosty mornings? Yes. Am I in danger of asphyxiating from it? No, and I think that's a critical distinction - some of my friends are, they should use an inhaler to counteract their body's over reaction to the conditions. Can I get over it without medication? Yes. Would I be faster if I had blood salbutamol levels of 800 ug/L instead of 0 and an unrestricted airway? Yes, whether I used it in training to work out at a higher level than I otherwise could, raced with it, or both.
I'd be interested in an analysis of those cross-country skiers if they compared the mucus and muscle response of the undiagnosed and diagnosed athletes with and without their inhalers. Do an EVH test and take an ultrasound of the larynx/trachea to measure smooth muscle constriction and mucus production after 15 minutes on the treadmill at 68F/20C and 50% RH, open the door and do it at 32F/0C and 5% RH, then take a hit of an inhaler and do both again (with appropriate breaks between tests). It could also be interesting to look at the responses of non-winter-sport athletes transplanted from warmer climates versus those who have been working out in those conditions for a few months.
It would be hypocritical not to admit that I occasionally take a pseudoephedrine throughout the fall because my nasal mucus membranes get more productive when raking dusty leaves or running through fields of ragweed - which is, again, pretty normal. To me, the main difference is that suffering through the snot doesn't lead to overcoming it, it's just gross and annoying.
