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Gauging Hyperventilation

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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New Member
Feb 25, 2002
I have been doing some wondering lately about the merits and dangers of mild hyperventilation. The standard response is that the effects hyperventilation are variable and that makes it dangerous. I have been able to notice significant differences in the number of rapid breathes that it takes to get mildly hyperventilated, ie a little light headed. When I am warm, ultra relaxed and in the zone 3 breathes gets me there. If I am cold, or not fully relaxed, etc, it takes more than a dozen.

My question is this. Could you gauge where you are at in O2 consumption rate by the number of rapid breathes it takes to get light headed. Then relax again and use that info to decide on a number of rapid breathes that will be safe for the next dive. I can understand that having a set number, say 4 breathes, would have a variable effect (as shown above) and thus be dangerous, but could the test and adjust method be safe and consistent?

Flame away,
The urge to breathe is not triggered by too little O2, but but by
a high level of Co2.

If you hyperventilate, you flush a lot of CO2 out the body,
but you only take up O2 for a portion of this time.

More sense: You can flush out more O2, than you can take up O2,

If you hyperventialte, you make your body think you have more O2 than you actually have.
You then hold your breath, and you still feel ok because you have flushed out a lot of the CO2, and in the mean time, your O2 level has dropped to a dangerous level....

it is then when a blackout sneaks in like a thief in the night !

I hope this makes a bit of sense to you.
Sure, I understand the issues with lowering C02 and why it increases the danger of black outs. That said, many people still advocate performing a couple rapid breathes before going down. I don't think anyone says to actually hyperventilate.

My point is that I partly agree with the idea of taking a couple of rapid breaths. It does, mean you are at a lower 02 level for a certain C02 level, but the advantage is that you then have a reduced mental stress buildup and also lowered physiological response. Benefit is that you remain calmer towards the end of the dive, your heart rate does rise up as much and thus use less 02. Obviously overdoing this leads to black out. What I have noticed is that in certain cases when warm and very relaxed, that even 3 or rapid breathes will give me a mild hyperventilation reaction (light headed) vs other times when I can barely get anything off of a dozen rapid breathes.

My hypothesis is that your body is generating C02 back into the lungs at a certain rate. When warm, relaxed and detached your metabolism is very low and muscle 02 usage is low. In this case the C02 rate going back into the lungs is low. So for a set breathing pattern, ie your breath up, you end up having a set flow rate of fresh air into the lungs to clear out this C02. But since C02 production is low, you end up with the overall percentage of C02 being low. Hence, only a couple of breathes cause mild hyperventilation. In contrast, when cold or not totally relaxed your C02 rate from blood into the lungs is higher. But, if your breathe up is exactly the same then the percent C02 in the lungs ends up being higher.

It seems like the goal for both performance and safety would be to start each dive with the actual percent C02 in the lungs at a consistent value. If your breathe up is successfully saturating your blood with 02 then you end up having consistent corellation between what you sense, raised C02 levels, and your dropping 02 levels. Therefore I think it may make sense to do few or no rapid breathes when warm and extremely calm, but when metabolism rate is higher (cold, not relaxed, tired, etc) that you perform more rapid breathes before diving.

This is all fuzzy theory, but was hoping for some feedback from others.


I agree, that a few breaths makes is easier.
What works for me, is to find your 'limit' with no hyperventilation,
and when its time to perform, take 3-5 big fast breaths, and STOP
when the time says so, not when you feel like it.

I also get the same difference between cold and warm water.
The thing is, it depends on so many factors.
It is a day to day thing.

One would be able to get a standard, by doing this a lot of times,
and then analyze it afterwards.
Me thinks it will result in a few blackouts, so as long it is in a controlled enviroment, its ok. (errrr....im going to get it)

I see a blackout as part of the sport.
If it happens, it happens.
As long as you are prepaired for it, and you long to do it all the time.

To get back to the point.
I found that 3-5 big fast breaths does it for me.

Any other care to comment ?
Well guess lots of people will get it in the neck for this, for me personally up to 3 deep fast breaths increases my down time by approx 30 secs, is 30secs worth risking your life for? Answer that yourself.
Obviously any form of hyperventilation increases the risks of an already dangerous sport so be careful have a buddy and dont push anything.
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