Hyperventilation before a burst of metabolism
Richard Cavell
During a burst of energy (such as a fight), most people will use up their
oxygen reserves pretty quickly. They then run on anaerobic metabolism.
Arterial pO2 can be artificially raised by breathing oxygen concentrations
that are higher than that found in air (as in a paramedic supplying oxygen
by mask), or by hyperventilation.
It occurs to me that oxygen therapy before a burst of metabolism could well
delay the switch to anaerobic metabolism, and delay an oxygen debt. Has
anyone tried this?
Surely I'm not the first person to think of this. So why don't Olympic
swimmers walk out to the blocks with scuba tanks attached to their faces?
Harry Mofo
>Surely I'm not the first person to think of this. So why don't Olympic
>swimmers walk out to the blocks with scuba tanks attached to their faces?
Scuba tanks are filled with air, not oxygen, so it would make them look silly and probably hurt their neck too.
--
Harry
Carey Gregory
Since someone else has already pointed out that scuba tanks are filled
with air, not oxygen, I'll merely add that the primary effect of
hyperventilating is to blow off CO2. It doesn't raise O2 levels
significantly. There's not much a normal, healthy person can do to
significantly increase their O2 saturation. Even breathing pure O2
has a minimal effect.
Steve Harris
That's true when resting, but it may not be true if you've got a severe
V'/Q' mismatch. Also, you can always raise your SpO2 a little with pure O2
breathing, as even normal lungs have bit of "physiologic" shunt. At sea
level you'll see you SpO2 go from 94% or so in a young person to 99.
If you've hit your anaerobic threshold it can be for a number of reasons,
and one of them can be that you've hit O2 delivery limits due to inability
to let your venous sats (which you never see with a pulse oxymeter) fall any
further and still extract O2. You can up that a bit by O2 breathing to
slightly increase your arterial content, and thus delivery, even if your
arterial Sats are good on air and your shunt is no worse than normal. You
don't affect it much, but 5% can be felt. You can see this effect on
endurance sports at even medium altitudes (like 4000 feet) even though these
aren't enough to affect resting SpO2 much in a healthy person.
BTW, if you'll pardon the personal subjective observation-- scuba tanks
aren't always filled with air, even for shallow sport diving. In fact I
typically dive EAN ("nitrous") when I can get it (which is most of the
time), and that's anything from 32 to 40% oxygen (this helps a bit on
nitrogen loading so you can stay at moderate depths like 70 ft for longer,
without needing decompression stops). It happens not untypically that after
a dive I have to do heavy ocean swimming against current or through kelp
beds to get back to a dive boat, and I can tell you that it certainly feels
easier to do breathing 40% O2 from my reg and tank, than it does air through
a snorkel. So much that I've given up even taking a snorkel. And this is at
sea level (exactly!) where I'm sure my sats are fine on air. Of course, the
endurance difference is subjective and certainly not double blind. Still, I
believe I can tell the difference between air and nitrox on surface swims.
(Divers typically surface with enough reserve gas for half an hour of
surface swimming). I once did a shallow dive on a tank of 50% oxygen which
I'd gotten by mistake from boat O2 fill error. Swimming back after that
one, I felt like Mark Spitz. It was only later that I put two and two
together.
For the Olympics there's no way anything you could put in a 40 lb pressure
tank would increase an elite athlete's swimming capability enough to
compensate for that much extra weight and drag-- even if it was legal under
Olympic rules, which I can hardly imagine it would be.
SBH
--
I welcome email from any being clever enough to fix my address. It's open
book. A prize to the first spambot that passes my Turing test.
Steve Harris
>BTW, if you'll pardon the personal subjective observation-- scuba tanks
>aren't always filled with air, even for shallow sport diving. In fact I
>typically dive EAN ("nitrous") when I can get it (which is most of the
>time), and that's anything from 32 to 40% oxygen (this helps a bit on
>nitrogen loading so you can stay at moderate depths like 70 ft for longer,
>without needing decompression stops
Drat my spellchecker. That's "nitrox" not "nitrous."
Carey Gregory
>That's true when resting, but it may not be true if you've got a severe
>V'/Q' mismatch.
And how many "normal, healthy" people do you suppose have such a
severe mismatch? ;-)
Steve Harris
That was phrased badly. Even if you're healthy and young you can go from 94
to 99% at rest on O2. And on exersize you may run less than 94% since that
normal shunt will be giving you badly desaturated venous blood (50% or even
less). Finally, the normal physiologic shunt and your A-a gradient all
increase with age. So those "master's class" olympians will get more from
the enriched O2 than the younger athletes.
Gee, now that I think about it, I got so much kick from 50% nitrox that I
ought to do some oxymetry on myself after heavy exercise to see if *I'm*
desaturating on exertion ;( I know I'm fine at rest, but maybe I have
some PAH or a small PE or something nasty that I haven't picked up. I really
could be in much better shape for my age-- it's not like I routinely run
marathons-- so I have lots of room to hide a little pathology.
Richard Cavell
> hyperventilating is to blow off CO2. It doesn't raise O2 levels
> significantly. There's not much a normal, healthy person can do to
> significantly increase their O2 saturation. Even breathing pure O2
> has a minimal effect.
I'm not talking about haemoglobin saturation, but the absolute partial
pressure of oxygen within the blood. This can, sure as hell, go to double
the normal value with oxygen therapy.
Andy
NANGANANGANANGANANGANANG
<giggle>
"Steve Harris" <sbha...@ix.RETICULATEDOBJECTcom.com> wrote in message
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apt76
"Richard Cavell" <richar...@mail.com> wrote in message
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This may be true, but what would it accomplish? The PaO2 may very well
increase (although I doubt it would DOUBLE??), reflecting more O2 dissolved
in plasma.
But O2 dissolved in plasma would STILL represent such a miniscule proportion
of O2 delivery to the tissues that, IMHO, I doubt it would enhance
performance or alter subsequent cellular metabolism in any way.
CBI
"Richard Cavell" <richar...@mail.com> wrote in message
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The problem is that almost all the oxygen is carried on hemoglobin and very
little is dissolved in solution. Doubling a very small number leaves you
with another very small number.
--
CBI, MD
"Believe those who are seeking the truth; doubt those who find it."
-Andre Gide