# freediving



## Bigg J (Nov 7, 2007)

I've been reading and watching videoswith freediving andspearfishing and what not. And then I read about shallow and deep water blackout. How do people freediving to whatever depth prevent that?


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## [email protected]IP (Mar 20, 2008)

Being in good shape helps alot...it happens most when people do too many dives in a row or if they are tired from wresting with a fish or current or something like that.


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## Mike aka FishWerks (Oct 22, 2007)

> *overNunder (11/15/2008)*I've been reading and watching videoswith freediving andspearfishing and what not. And then I read about shallow and deep water blackout. How do people freediving to whatever depth prevent that?




Here is some info from the US Navy Dive Manual; 

"Breath holding and Unconsciousness. Most people can hold their breath approx-

imately 1 minute, but usually not much longer without training or special

preparation. At some time during a breath holding attempt, the desire to breathe

becomes uncontrollable. The demand to breathe is signaled by the respiratory

center responding to the increasing levels of carbon dioxide in the arterial blood

and peripheral chemoreceptors responding to the corresponding fall in arterial

oxygen partial pressure. If the breath hold is preceded by a period of voluntary

hyperventilation, the breath hold can be much longer. Voluntary hyperventilation

lowers body stores of carbon dioxide below normal (a condition known as hypoc-

apnia), without significantly increasing oxygen stores. During the breath hold, it

takes an appreciable time for the body stores of carbon dioxide to return to the

normal level then to rise to the point where breathing is stimulated. During this

time the oxygen partial pressure may fall below the level necessary to maintain

consciousness. This is a common cause of breath holding accidents in swimming

pools. Extended breath holding after hyperventilation is not a safe procedure."



A couple of other thoughts, be healthy, know you body and your limitations. Work up to deeper and more frequent dives and always dive with a buddy or some sort of team. Hope this helps.


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## Evensplit (Oct 2, 2007)

Training and experience help and don't push your limits, but there's no guarantee that it won't happen on any given dive.Always have a safety diver on the surface.


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## Bigg J (Nov 7, 2007)

Right on, thanks guys.


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## Clay-Doh (Oct 2, 2007)

Kinda the same principle as the "sleeper" wrestling move.....cut off oxegen, overtoxify the body with CO2, and you are "voluntarily" putting yourself in a sleeper.


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## jan1974 (Apr 17, 2008)

Always freedive with a buddy and never hyperventilate. Freediving blackouts are the point which a diver may lose consciouness due to one or more conditions.Lack of oxygen,lack of blood flow or an increase in carbon dioxide.



The urge to breathe is triggered by rising carbon dioxide (CO2) levels in the blood.Hyperventilation artificially depletes this (CO2) causing a low blood carbon dioxide condition. After hyporventilation during the freedive your CO2 level is very low. Your body delay the urge to breathe and leaves the freediver susceptible to loss of consciousness from hypoxia(lack of oxygen) in your body.So when you hyperventilate you just extend your dive by closing down the body's natural breathing mechanism, not by increasing oxygen load.This is very dangerous,because you don't have any or minimal urge to breathe during your freedive.And as soon as your level of oxygen drop down to some critical limit, "click" and you lossing consciouness. Then you wake up in your buddy's arms,if you have one,very surprised what happened,because you felt so good on your dive and did'nt know it's coming. If no buddy, you gonna sink all way down to the bottom and drown. There is around 50-80 fatal freediving-spearfishing accidents around the world every year.It makes it most dangerous sport in the world.





I personally experienced two blackouts.The first one was on 160ft dive I blacked out just 5 ft below the surface and second one was in the pool during dynamic apnea(swimming distance underwater) both in the freediving competition with a safety divers,so it was'nt a big deal.



How to avoid a blackout? My suggestion is: never hyperventilate(in most cases SWB is due hyperventilation)

never dive without a buddy(with some freediving experiences)

your surface interval between dives should be at least 2-3 times

longer than your dive time. for example: you spend underwater 1 min on your 

freedive then you resting 2-3 min on the surface.



http://www.deeperblue.com/ here you can find a lot of answers about freediving.







Freedive safe JAN


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## Bigg J (Nov 7, 2007)

Thanks guys


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