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lung volume during statics

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Apnea Carp
Oct 11, 2003
I have noticed something interesting when doing dry statics, and don't know how to explain it. When I do a static, I take a really deep breath and do 2 or 3 packs. At this point, my lungs are completely full - nothing else fits! When I finish the static, about 4 minutes, sometimes the first thing I do is breathe in, before releasing the air I'm holding. Where has the extra space come from? Have I really used that volume of oxygen?! I definitely don't release any air during the static.

Hope someone can help :)

Same experiance. I think things are just stretching a bit. Anybody got a more interesting explaination?

Sorry for my English ;-).
I suppose that phenomenon may be caused by fact that your body uses oxygen during static. Your organism uses oxygen and produces carbon dioxide. And I think that volume of used oxygen is larger than volume of produced carbon dioxide.
I think that is possible. Try following experiment:
Take a candle, glass jar (jar has to be higher than candle) and sort of bowl... Put candle in the center of the bowl. Next put some water into the bowl and lit the candle. Take the jar, rotate it upside down and cover the candle. The candle will use oxygen and produce carbon dioxide. And you would be able to see that water from the bowl start to fill the jar. Finally the water, will fill approx. 20% of jar’s volume. So – as you can see – the water fills space that was filled by oxygen.
I think that something similar occurs in your lungs. You use oxygen that is reason that you feel “free space” after static.
I hope you was able to understand my English ;-)
See ya.
Something doesn't seem right about that. The O2 doesn't go anyplace. Each molecule changes from O2 to CO2 by combining with carbon. Can that reduce the volume by 95%? Is CO2 20 times the density of O2?
I've noticed the reduction in lung volume but, always thought it was the stretching, never measured it.
But in example with jar - 02 doesn't go anywhere as well. Just combine with C!!! Same situation.... It doesn't reduce volume by 95%!!!! Water fills about 20% of jar's volume... Have you tried experiment??;)
best regards, andrzej
I do remember seeing the experiment but, I'm still confused Andrzej. If the O2 becomes CO2, why doesn't CO2 take up the same amount of room that the O2 did. The 95% referred to the fact that 79% of the glass is filled with N2, the 21% O2 goes away and the CO2 produced doesn't take up any/much space.
Yes volume is lower after breathhold.
It can be that CO2 is more dense. Air is also matter and matter can be of more or less density.

Try this: hyperventilate + breath oxygene - hold your breath.
After some 10 minutes you will clearly see, feel that you have less air left. It is actually said that the sinking volume is what limits this kind of breathholds - after some 20 minutes your lung can reach RV. So I have heard.

You are right Bill. My fault. I sat down and wrote reaction. If you take 0,54 g of carbon and you burn if with 1L of oxygen you will get 1L of carbon dioxide.
You was right Bill.
I forgot about one thing. We have to remember that burning candle produces also H20.
Simple reaction:
C57 H110 O6 + 81,5*O2 --> 57*CO2 + 55*H20

(C57 H110 O6 - is a substance that a candle is made of. I don't know its English name)

So – some oxygen changes into water. And I think that’s the reason that the water is “sucked” into the jar.
I suppose that humans body produces H2O too.
See ya.
Your knowledge of chemistry is far better than mine. Thanks for the work.
Thanks for the chemistry - I think the human body does produce H2O, so this might explain the change in volume. I am doing a science foundation course and therefore have access to pure O2, but the university staff would probably not be very happy to find me experimenting with the effects of O2 on breath-holding. :naughty Maybe they wouldn't mind so much if I drew a nice graph of the results! ;)

I found out the equation for the use of glucose (the body's main fuel):

C6H12O6 + 6O2 -----> 6CO2 + 6H2O

The H2O would probably remain in the tissues, and once the air in the lungs is saturated, some of the CO2 would build up in the blood and tissues, so this would explain the decrease in volume.

When you produce CO2, much of the CO2 will dissolve in the blood plasma and body water (see CO2 compartment hypothesis thread). CO2 which is dissolved in the body water and blood doesn't take up any volume in the lungs. This is one reason for the decrease in lung volume during statics.

However, your respiratory quotient also determines how much your lung volume will decrease with time. If you are burning 100% carbs, then RQ=1.00, and for every O2 molecule burned, one CO2 molecule is formed. If you are burning pure fat, RQ = 0.7, and for every O2 molecule burned, only 0.7 CO2 molecules are formed. Thus, when burning fat as fuel, your lung volume will shrink more and faster than when burning carbs.

Eric Fattah
BC, Canada
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