That sounds reasonable, but even then it doesn't mean someone shouldn't wear a mask. Their performance would be decreased, but it doesn't mean that it would be medically dangerous (they would not have low blood oxygenation, for example).

I'm currently dating a 6th grade school teacher. She said when they returned to school with masks the kids were for sure more lethargic and even woozy more often than she had ever seen in her 10 years teaching. As masks were removed over time, it went away more and more.

There are lots of other explanations for that. For example, it could be confirmation bias. It could also be that a lot of the kids had long COVID and the effects are wearing off over time.

Makes sense, since we have zero proof of any real reason, let's go with the ones with even less obvious explanations.

Children and long covid? Children barely got covid in the first place... Long covid? In so many kids a teacher could notice? Give me a break.

It occurred to me that cycling primarily involves heart, lungs, and legs. You train all of them simultaneously, so they'll naturally have balanced performance. If you selectively impair one of the three, it will become a bottleneck. However, it seems to me that the lungs have the easiest job (e.g. cycling is easier than tasks like inflating balloons), so it should be possible to recover almost all the lost performance by training with the respirator on, bringing the lungs back into balance with the heart and legs.

What's the point of that when there's no need to wear a respirator in the first place?

The point is to acknowledge a limitation of my testing.