I know the O2 trainer is not a mask, I said as much a few posts back. And none of these devices have anything to do with altitude training, regardless of the claims by their purveyors.
The "O2 trainer" works on the same principle as masks, they all restrict your air intake and make it harder to breathe. Not your O2 intake. It ain't rocket science. I couldn't find anything on-line about the O2 trainer specifically, other than promotional videos done by its maker. I tend not to trust those.
The only objective info. is a few studies, the most recent I could find in 2016. It's cited in the fox news piece, which is IMO a good critique on all similar devices.
My response was to Scott. I just took your post as well because it did have the article about the typic.
