I am double vaxed+boosted, and I still wear a mask everywhere I'm required to which includes still going to the gym 3-4 times a week.

My gym has gone back and forth between masks being required or not with the case count. I know I've read everything about airflow being fine, and there being no reduced oxygen intake, but having worked out with and without a mask depending on location in the past 2 years I can attest anecdotally as somebody with no health problems that even if only anecdotal it is way more taxing/difficult to recover breath when working out with a mask on, and can be borderline anxiety/torture especially after very intense sets or cardiovascular effort.

It easily takes me at least a couple more minutes to recover my breath/rest in between very hard sets of heavy squats for instance as compared to when not wearing a mask.

As an aside, have you noticed any improvements from training with a mask on? Is it like how runners might train at high altitude, so when you come back to normal levels you are more efficient?

A good while back I looked at restrictors for training and my recollection is they didn't show any benefit in studies. Unclear why. They're a lot tougher than any respirator I've tried so I wouldn't expect the respirator to have any benefit that direction. Altitude tents apparently do work but are more trouble and risk than I'm comfortable with.

The only thing I could say is I have improved some at working out with a mask on, but it's still noticeable by a large margin more difficult to recover my breath/energy than without.

I don't think I've generally seen that transfer over to performance without one though.

Thank you