Running in cold weather with asthma can suck the wind out of your training, literally and figuratively. I’ve battled asthma since my early teens; some days, it is so cold that I step outside and instantly can’t breathe. For many years, my training would taper off significantly in the winter due to my asthma.
Asthma makes your airways extremely sensitive, and cold air is one of the triggers that can cause the airways to spasm. When that happens, your whole chest tightens up and you cough, wheeze, and gasp for air. I would try running in the cold with my face covered and only my eyes exposed, but breathing was still a challenge. I’d find myself stopping and coughing a lot. My inhaler didn’t help much, and the cold weather usually won. It’s hard to enjoy running when it takes so much energy just to breathe.
The first few years I was into running, I would just take the winter mostly off. I didn’t have easy access to a treadmill in those years, and the downtime didn’t bother me. However, I would run the same spring half marathon every year, and for a few years in a row, my finish time was almost exactly the same. The lack of progress started to get frustrating. I could see that to get faster, I would have to avoid such a long break in training.