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Hi Jason,
On Tue, 13 Dec 94 12:18:22 GMT J Shepherd wrote:
>
> The absolute production of CO2 is metabolism related - since
> this is not depth related, the amount of CO2 remains the smae regards of
> depth (since you are breathing out, the ppCO2 in you lungs at 40m, 80m
> or 0m is the same). This backs up to your brain, where the CO2
> equilibrates into the wet bits of your brain and alters the pH. The is
> picked up.... somewhere, and increases drive and the breathing reflex
> (i.e. I gotta do something, and the something is breathe - if you can't
> breathe you still gotta do something so you panic).
>
> You don't *need* to in terms of O2 intake, but in terms of
> metabolic by product, you do want to...
Does this mean that if you run out of air @ depth & if you don't
breath (obviously), if you have a 'will of iron' you will feel like shit, but
won't blackout due to O2 starvation as quickly at depth as on the surface ???
I once held my breath for 3 mins....relaxed & sitting in an armchair.
"Why ?" you may well ask. I'm not sure I have a good answer, apart from just
seeing if I could. It felt pretty awful & I would have hated to even do 1
minute
underwater. (I'm sure we will now have a flood of people saying they can do it
for even longer... :-) )
Anyway on the Discovery Channel a couple of days ago they showed one of
the 'free divers' snorkelling down to 80 metres....without a weight to speed
him
down, nor with extra bouyancy to bring him back up....pretty impressive !!!
With extra weight to get down & a bouyant ascent the limit set was 120 metres.
This is considerably more than the guys portrayed in the "Deep Blue" film set
in
the 60's. Anyway, as an aside they stated that the record for breath-holding
under water in a swimming pool was 7 minutes (!) I presume that in doing this
the 'pain barrier' of CO2 build-up is overcome & that the real limitation is O2
blackout. If so, could the same person hold his breath for 28 minutes @ 30
metres, where the ppO2 is 0.8 bar. This doesn't seem likely ..!! Hence are
you
correct in your original supposition or are there other factors to be
considered ?
Regards, Steve M.
ps..no real practical use to any of this...just the product of a
rambling mind...but then isn't 90% of the techdiver listserver ?? *This* is
the
time to don my asbestos suit..! :-)
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