Eric and all,
That’s really interesting. I’m really having fun with this oximeter. I have been closing comparing my results to Sebastian’s on his site
http://www.webvideo.nu/freediving/features/breathhold.html . My holds are not nearly as long as his for three reasons. First I’m not as good with a PR of only 6:00, 2nd I’m not doing nearly the proper preparation and warmup he did, and second I’m not in the nice relaxed state of lying down.
Instead I’m at a desk and watching the watch, the heart rate, and the O2 readings and writing it all down. I purchased the inexpensive Nonin Onyx (all in one) unit, which from reading the info is suppose to have the latest technology and is very accurate, but there is no recording feature – so it just me and my pencil until I can get someone to do it for me.
And interesting comparison to Sebastian’s results is my O2 drops faster than his at first to a maximum of 5% less at 4:00 min, but my heart rate is lower through out and at 3:00 min it reaches a max lower of 42%. At 4:30 my O2 is only 2% lower than his, but my heart rate is still 31% lower. I’m hoping this trend continues to where my O2 doesn’t fall as fast and is eventually higher than his at later times, because my metabolism is less and using less O2.
If this theory is true it will be consistent with my experiences. When I have a good hold I will go through a hard struggle phase with some pretty good contractions, but then things get better and I feel like I am in a zone. If I’m in a pool with a spotter they get pretty concern that I have reached my limit much earlier than my true limit is. It also is consistent with the loss of heat and blood to my extremities I experience.
Eric what is your heart rate at 4:30 or 5:00? How does it affect your O2 use? Anyone else?
Don
PS Rik and Ben thanks for the info on CO2 tolerance. The really cool thing about an oximeter is it helps you determine what your limiting factors are. If you are stopping your holds at 70 –80% O2 than the limiting factor is not low O2, but instead CO2 tolerance and mental control. I would love to have the ability of Eric Fattah and Sebastian to take it to the limit!