[IronLung]

[quote=wes;639091 As far as the SA02 oxygen levels read out, they stay at around 98% for about 1/2 of the breath hold (this is when there is still plenty of 02 in the lungs). Then the 02 levels drop off slowly for the next 1/4 of the hold (this is where the rest of the 02 from the lungs is getting used up). Then for the last 1/4 of the hold the 02 level "plummets" (this is where the 02 from the lungs is pretty much used up and you are using up the 02 stored in the blood by the hemoglobin). [/QUOTE]

This sounds interesting. I wonder if it would be beneficial to do multiple breathhold up to the point where O2 levels "plummet" in the last quarter and stop right there? I.e. about 3/4 breath hold each time.