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Be careful out there

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Well-Known Member
Aug 7, 2001
I have such experience concerning emptylung statics that BO might be easier to get when using hyperventilation (for example one of my friend did BO at about 2.45 with empty lung static. His normal static PB is 5.06)

Also O2% in blood drops quite quick comparing normal statics (measured with the two differend O2 meter). So if you do that in the water be extra carefully and never do it alone (remember compared to normal statics BO:s there will be no ventilation out when BO comes, only in when time goes far enough).

Best rgds,

- kimmo
Thanks Kimmo,

Words of wisdom, no doubt.

I want to share an important peice about blacking out:

Your partner can sometimes take as long as 30 seconds before they look like they are going out. KEEP WATCHING YOUR DIVE PARTNER AFTER THEY SURFACE!
Notice if they are putting the snorkle back in etc.
People who are blacked out will still give you the "OK" sign.

The physiology is this:

it takes about 3-5 heartbeats to get O2 saturated blood from the lungs to the brain.
the act of breathing uses O2
"samba" uses even more O2 and very little O2 gets in the lungs when your diaphragm muscle is spasming

I have watched divers who have given me the OK sign (with their feet on the bottom of the pool) start to sink under the water after breathing for about 15 seconds.

Please watch closely, your partner is counting on you.
Last edited:

You are absolutely right Octo,

In measurements which I made (conserning O2 saturation in the blood while static apnea) I also found out that O2% still drops about 15-30 seconds even the breathing have been started. And the drop angle is same as it is in the end of the static apnea before breathing.
So I suppose that the most critical freediving moment is just after apnea when breathing again :)

- kimmo
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