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Thread Status: Hello , There was no answer in this thread for more than 60 days.
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We pee deep. Ew!
Sep 24, 2002
I was chatting w/ someone recenty and they mentioned that they knew someone who would stay underwater for "a long time" by breathing out air into a pocket and then breathing it back in. After thinking about this a bit, I concluded that it might be plausible. Dangerous, but plausible. I figured I'd run this past folks to see if my reasoning is correct.

Before reading any further, note that this technique, if it works, is probably a great way to black-out and die.
- Don't try this at home
- Don't get all clever "try it at the local public pool instead".

Water absorbs Co2 pretty readily. If you breathed out into a pocket that had a large surface area, wouldn't some of the Co2 diffuse into the surrounding water? Could enough Co2 diffuse in this way to suppress the breathing urge a bit? What if you used "bubbling" to overcome surface tension, increase area etc. Basically, this would be a crude re-breather that didn't need sofnolime ... For the limnologists out there, could you actually pick up some O2 if you did this little circus act in the metalimnion of a lake with a positive heterograde profile (note: I have no clue what this means)?

The rate of diffusion should go up with depth (assuming area remained constant) and also go up with rising levels of CO2 since both factors increase partial pressure of CO2. Since CO2 diffuses into water at 18x the speed of O2, the loss of O2 should be small in comparison to the loss of CO2 (note, Co2 is 22x more soluble than O2, but the larger molecule size slows down the rate of diffusion -- the assumption here is that the CO2 dffusion will not change the concentration of the body of water in any significant way).

Doest the act of breathing itself satisfy the urge a bit, even if there is no net change in gas composition? I realize here that breathing may have an undesireable effect of raising the heart rate, overall metabolism etc, but that is a little beside the point...

It seems clear that this technique, even if there is any merit to it, would not help a champion apneist stay under longer, since the reduction in blood pH helps with tolerating low Co2 levels. However, it seems like it might allow someone who is CO2 "intolerant" to stay under longer than they could otherwise.

I just want to repeat that if this worked, it would be extremely dangerous because the increased comfort level would be deceptive and the reduced Bohr effect would increase the likelihood of passing out -- so I'm asking this question from a theoretical viewpoint and not advocating it as a useful technique. I just thought that it was an interesting idea, and I wondered if my rationale was right.
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Years ago it was shown that re-breathing into a plastic bag significantly reduced the breathing reflex, and scientists could not explain the phenomenon.

Eric Fattah
BC, Canada
I think that something related to the "plastic bag" idea is somehting the you mentioned a while back, and that involves inhaling solely through packing.

I find this excruciating, even if I pack fast enough that I know that the rate is inhalations is close to normal breathing. In that post, you mentioned that it "massively blunts the breathing reflex" and I agree.

Maybe the rhythm of breathing is one of the feedback mechanisms that the body uses and stimulating that feedback path satisfies the breathing urge, while suppressing it causes the bodly to (over time) pay less attention to that feedback mechanism.

10x for the reply!
My thoughts (for what they are worth):

One REGULAR breath uses around 10% of the O2 that was in the air - this is why CPR works. Only the surface area of the lungs is
capable of absorption, even then, only in the avlioli. The rest of the O2 never comes in direct contact and is unchanged.

Breathing out into a bag and rebreathing the air gives you another fresh lungfull..... but.....
most people are thinking... ok..10% each breath = 10 breaths at 100% right?
The same air being depleated to 90% usable after the first breath is NOT 80% after the second.

The same volume of air keeps going in but the % of O2 is lower. The lungs dont absorb 10% O2 automaticly, they just happen to
because thats how much Oxy was touching them on that breath. there is the same amount of air the second time, but the amount of O2 is reduced, so you cant get a full 10% on the second breath.
Each time it gets worse. well.. you knew that.....

But for 3 or 4 quick breaths it will give you a couple extra minutes if you are relaxed enough. a couple does not mean several!
So dont call me a fool if you die ok? ok....

Now..... has anyone heard of "recycled breathing"?
Suposedly some musicians and pearl divers have this "lost art"
that enables them to purge air from their lungs without exhaling. this passes the air over the surface SEVERAL times to keep the alvioli enriched, and to use every possible ounce from each breath.
err.....Are you supposed to swallow it and burp it back up?
or just puff it into your cheeks?
I've tried both... just to see if it was actualy possible.
both options left me popping up to the surface quickly (and I usualy stay down for quite a while.)

technique is supposed to be similar to those tibetan "throat singers" who can produce multiple notes at the same time
Anyone with information or theory... chime in
I don't know if what you mean is the same as "circular breathing" which is used by wind instrument players. This consists of first blowing out through the mouth, then filling the cheeks with air and breathing in through the nose while blowing out the air from the cheeks. It allows very long notes to be played, which could not be done on one breath. Useful for playing the trumpet, but for freediving :confused:

As far as I know, the technique of Tibetan throat singers has nothing to do with circular/recycled breathing, as it involves singing a very low sustained note while giving resonance to much higher notes above it. Again, for freediving :confused:

Ok, gotcha....
Im working off second or third hand info here. Heard from various sources.
Yeah... circular breathing not so great for diving...

But supposedly pearl dives in Edo - tokyo- used RECYCLED BREATHING a thousand ago..... that in combination with holding breath thay could stay under a VERY long time.
I saw something on TV about it a LONG time ago....
I dont know if was nova or nature... or one of the BBC shows they
import for us sometimes..... i wish i could find out where i saw it.
then Id only get funny looks HALF the time... heh heh
I've always wondered what the purpose of contractions are--perhaps to increase the BP in the brain? Or, perhaps they are a sort of re-cycled breathing where the body is trying to move the air around the alveoli.

Eric Fattah
BC, Canada
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efattah- that's funny, I was going to write almost exactly the
same thing.
Well...... breathing into a bag sounds kinda boring....
I remember hearing a LONG time ago, that the worlds record for the longest underwater kiss was ..... 11 or 15 minutes.....17?
I cant remember.... prob 11....... but it been a while. It could have changed.
sheeesh...... Ive had too many gilrfriends who were the type that was afraid to get their hair wet....... literaly....
But it would be fun to try and break the record.
Anyone willing? (wink wink)
Hehe.. This thread brings back memories. My friend and I used to play with a rescue doll in the pool. A very easy plastic design doll.. It had a small hole on the head and a big hole at the bottom.. We would sink the doll and breathe air into it as we held the finger over the small hole at the top.. Then we would suck the air out of the doll and re-breath it.. And when we filled it with much air we could stay under for many minutes that way..
a few years ago while using SCUBA in a swimming pool, I used my BCD as a rebeather for maybe 1 or 2 minutes. The idea was to try this to see if it could work in the event of a regulator malfunction during a real dive when a minute or 2 of "creative" use of the equipment on hand would save me from the results of stupidity of poor dive planning. Even though I was in a shallow pool, the breathing seemed to work OK but the amount of CO2 remains to be the question at hand.
I've thought about using bcd air in case of an out of air emergency also, how did it work? I figure if it comes to needing
the bcd air you are REALLY hurting.
it was is a controlled setting, I'm sure in a near panic situation it would have a few problems, but I'm sure the one or 2 breathes one take would help for a little bit of time. Dalton's law and the concentration of CO2 would come into play with greater depths. Now the the use of pony bottles or spare air, a diver shouldn't have to use a BCD as a rebreather.
I see you are from Dana Point Ca, last year I was activated in the reserves and spent several months at Camp Pendleton which is close to where you are. How is the diving in that area?
i practice around halloween with masks that have the breathing holes blocked while trick or treating or handing out candy(usually the latter) rebreathing the same air for many minutes. i get semi contractions even though i'm breathing because the air is no good in the mask and the feeling is like i'm holding my breath not in my lungs but in the mask. i'm not alone on halloween so if i passed out my friends would help me.
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