Thursday, April 23, 2009

FRC statics and depth training

Here in The Netherlands there are not many lakes over 30 meters deep. The deepest one I know of is 52 meter deep. My max. depth so far is just 43 meters but with the recent successes in the pool I'm sure I will go deeper not to long from now.

Inspired by Eric Fattah's very impressive FRC dives at the Vertical Blue competition in the Bahamas I decided to practice my equalisation skills a bit more by dives on half full lungs the next period. Last year I did 21 meters on FRC and this year, with more ease, I equalled that plus I did 28 meters where I'm not sure if I took the exact same amount of air with me. Anyway, making progress with equalisation and having much more relaxed abdominal muscles and diaphragm.

I have done some FRC statics to get a feeling of where I stand at the moment. These are some stats...

FRC static dry
1 exhale:
2:56 83% SpO2%
2:52 87%
3:07 83%
2 exhales:
3:13 82%
4:20 74%
1 exhale:
4:05 73%
3 exhales:
4:32 64%
2 exhales:
3:40 75%

FRC static in the pool (SpO2% unknown)
2 exhales:

So 4:32 dry, 4:11 wet.


  1. Hey Eric, what oxymeter are u using ? (i'm thinking of getting one my self) as far as i know there readings stop being accurate around 75%.

    I also didn't understand the exhales, what do you mean 3 exhales ? is that an indication of the extent of your exhale ?

    any ways its always a pleasure and interesting to read your posts.

  2. Hi Eric, nice blog. I like to read it. I appreciate that you write it in English despite it id not your mother language.

  3. With 1xexhale I mean that for the last two minutes I do tidal breathing and than one exhale, inhale, relax and hold. With 2x exhale I do another inhale and exhale prior to the hold.

    The oximeter is an Onin Medical, looking similar to this one.

    The document says it is indeed accurate 70-100%, but I find that it goes down way beyond 70%. Perhaps 50% can mean 47% or 53% but on average it gives a good indication. Yes I know vasoconstration can make these fingertip oximeter drop very low while the brain has ample oxigen. I never use it to push to a certain value, just as an indication afterwards. I find it very useful and it always corresponds nicely with the hypoxic feeling I have after the static. Plus on no-warmup statics it time and time again shows me what a sissy I am when I am unable to get the oxygen saturation down to hypoxic levels.

  4. Hi MR,

    Thank you. It's good to practice English from time to time. I always try to put one word in my posts that I need to look up first. And BTW I make heaps of spelling mistakes in Dutch to, and of that I am really ashamed. :-)

    I am curious, who hides behind the letters MR?


  5. Hi Eric,

    Thanks for the post. Interesting to read. So all the dives in your table are with half lungs full?

    I don't want to discourage you but I once did a test at the hospital with the same nonin device you have at my finger and a professional machine attached to my forehead and my earlope.

    The results were so much different! Even without a warmingup there was already more then 10% difference. And after the warmup the difference was more then 30%. Vasoconstriction of course, as you describe it.

    So I don't find it strange that you can't get your oxygen saturation that far down without any warmups. People who do over 8 minutes in static aren't sissy... And now I think of it, nobody who freedives is a sissy... ;)

    Good luck with training.

  6. Hi Jorg,

    Yes they're all with half full lungs and about 2 minutes tidal breathing in between holds.

    I didn't know it was as much as 30%. I should try to do some tests with other equipment. But the point really is that the results of my oximeter seems a good indication between trainings. Next time I'll do the same training, I would compare the SpO2% of the first hold against the first one of the training I posted here. At the moment it's about 83% at 3:00 , 73% at 4:00 and 64% at 4:30 and perhaps fifty-something% at 5:00 .
    I will try to do 5 minutes between today and a year or so.