And once again this was a randomised controlled trial so your examples, as Brian pointed out, do not relate to the study we're discussing.

Also the snorkel example. A snorkel definately provides resistance. Absolutely no where near 50cmH20. Brian, as a man with experience of CPAP at 12cmH2O (not mmHg as you stated) knows that CPAP is much harder than a snorkel to breath out of but easier to breath in with. I also know that there's a massive difference.

So I imagine the difference between snorkel and 50cmH2O is a bit like me saying I've been doing arms at the gym today because I've lifted my coffee mug a few times.

The argument I think you're trying to make is based on sample selection. I agree that the magnitude of the effect will probably be different in elite highly trained underwater hockey players than in recreational swimmers. But again it's an RCT that seems to be reasonably controlled. So the effect will surely be smaller in elite UWH players but it might still be significantly better than what you do already. Brian pointed this out with his 3-4% argument.

Atapene. My side, remember? You Stirrer, you. (we used to be teammates and flatmates)