I tried a regime ( not very scientific ) last year with exhale holds, and didn't get good results ( in as much as experience counts - no blood measurements were taken ).
I was training in advance of a competition. My regime was along the lines of 2 minute hyperventilations, followed by a variable exhale hold.
These were all performed out of the water. The exhale included reverse packing, and the duration ranged up to about 2 mins or so.
I started to feel a bit unwell after about a week or so, and eventually caught a cold virus. I gave up that line of training, and reverted to Pelizzari / Solomon's 'A' & 'B' static tables instead.
The competition did not go well either ( apart from the CW ). Five months later I entered another comp where I trained much less, and rested more. I achieved much better results that time, particularly in static.
My concern with the exhale training, as I was not using a saturation monitor, was that I could be doing damage at the cellular and immune level. There's a bit more about it on
this blog entry, but you'll have to read around the other rubbish about cameras and computers.
