Thanks, SeaRat! Your AIR-1 data was terrific. Luis' points about flow vs. inhalation resistance not being equivalent to a WOB loop are appropriate, but it's still fascinating data.
I just have to comment on the above. 50 bpm is only hyperventilation when it's not driven by demand. The decreases in oxygenation are driven by the pH change in blood from respiratory alkalosis, if you blow off too much CO2 by hyperventilating. The blood oxygenates okay, but can't offload to the tissues as well when the pH is alkaline. There's also some vasoconstriction that happens when CO2 drops. A big deal in neurosurgery.
But in max effort exercise, your CO2 production is huge, and you need to breathe that much to both acquire O2 for your tissues and to blow off CO2 to preserve normal pH (not including whatever lactic acidosis you acquire from anaerobic metabolism by being unable to breathe enough for the exercise load). So in the hypothetical "big Navy diver", my presumption was that he was breathing 50bpm because he had to. Sorry I didn't make that clear.
"Enough for the USN" was really just a cryptic reference to their standards for military regulator testing at extreme depth and max RMV. Again, sorry for not explaining myself. I certainly agree with the risk to the out-of-shape fat guy outstripping his ability to oxygenate his tissues! Long live drift diving!
Doc
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