That’s interesting- thanks for sharing!

This does bring up other questions - how cold is too cold? Is 10F ok, 0F, -10F?

What about climates that get cold, but remain relatively humid (like Great Lakes region in the US)?

From personal experience it’s tough to do hard intervals/long runs when weather dips below 10F due to multiple layers of clothing required (especially when it’s windy). You are also likely to pull a mask over your face/mouth when it gets too cold (which I suspect slightly warms up the air that you inhale).

Further personally I have not noticed a dip in performance in winter/spring when I used to run exclusively outside (if anything - I race better due to weather being colder than in summer).

I believe it, I mean look at all the cross country skiers that need to take Salbutamol. #kiddingnotkidding