Interesting on your view of what a "proper runner" is. To me anyone who runs is a proper runner!
I can confirm that works in a different way, though; running (slowly) with untreated asthma basically altitude trained me, when they were doing the tests they found a very high level of red blood cells which was my body compensating, and when I got inhalers it fairly quickly dropped off again and was normal on the tests they did after that. That said, it did give me a bit of a kick of energy in the first few days of treatment!
It's unusual - to the point that it took doctors 3 months with some "cheating" by me[1] to work out what it was - but, perhaps relevantly, I developed asthma as a post-viral thing aged 38, I've not always had it - some sort of chest infection that seems to have caused lasting damage. Based on reports, some COVID patients will get the same thing, but fortunately if it is the same thing a preventer inhaler will "fix" it to allow activity to resume normally over time.
[1] I borrowed a spare inhaler off my sister and tried it. You're clearly not meant to do that, but the doctors were quite appreciative of my reports that it worked!![]()
Maybe competitive would have been a better word. But they use masks deliberately to restrict the amount of air into their lungs to make the body work harder not like in your case for medical reasons. The equvilent of a few extra weights at a gym or weights when swimming.