Cam's Blog

January 30, 2010

Carbon dioxide purging and weightlifting

Filed under: Exercise, Weightlifting — cfranc @ 2:25 pm

A couple weeks ago I stumbled across a clip of David Blaine giving a talk at a TED (technology, entertainment and design) conference. In the clip he describes his attempts to hold his breath for extremely long periods of time. The gist of the talk is that, rather than create an illusion, he eventually discovered free-diving and learned several techniques which allowed him to significantly increase the length of time that he could hold his breath.

Blaine describes carbon dioxide purging at 6:54 in the clip; to purge one breathes deeply and quickly in an attempt to rid the body of as much CO2 as possible and ensure that the blood is fully oxygenated. When I saw this I immediately thought that CO2 purging might be useful for weightlifting. The body uses oxygen and the chemical compound adenosine-triphosphate (ATP) during muscular contractions to provide energy. This creates carbon-dioxide as a byproduct, which is then flushed from the muscles through the bloodstream and out of the body via the lungs. I reasoned that if the CO2 levels of the blood were low to begin with, then this might result in a more efficient flushing of carbon-dioxide and thereby aid ATP conversion.

It sounds like a reasonable enough hypothesis, but unfortunately I haven’t been able to find any information which supports it. In fact, some things that I’ve found seem to suggest it might not help at all, or potentially even have a negative effect on a lift. For starters, CO2 purging is really just a brief period of self-induced hyperventilation. Surprisingly, hyperventilation has nothing to do with a lack of oxygen, but rather a lack of CO2 in the bloodstream. This is why people in the throes of an attack of hyperventilation will breath into a bag: it captures the exhaled CO2 and allows the sufferer to breath it back. Wikipedia describes the effects of hyperventilation on the body as reducing

the carbon dioxide concentration of the blood to below its normal level, thereby raising the blood’s pH value (making it more alkaline), initiating constriction of the blood vessels which supply the brain, and preventing the transport of oxygen and other molecules necessary for the function of the nervous system.

Constricting blood vessels and a disrupted nervous system? Sounds disastrous for lifting. Moreover, this informative article on breathing during exercise states that most people stay fully oxygenated during exercise:

Physical training or increased fitness does little to improve the lung as a mechanical pump or gas exchanger, unlike the beneficial effects of exercise on skeletal muscles and the heart. Luckily, however, the limits of operation of the lungs normally far exceed the demands placed upon them. For example, at maximum levels of exercise, not only is full blood oxygenation maintained in normal subjects, but also ventilation has not reached a maximum: it can be increased further by volitional effort.

If this is true, it implies that the only benefit that CO2 purging might give is a more efficient cleansing of CO2 from the blood stream during muscle contraction. Purging won’t increase bloodstream oxygenation, because your body already has you fully stocked even during the most intense exercise (although it’s possible that the author is using the word “full” here to mean an adequate supply of oxygen for proper muscle function. In this case further saturation might be both possible and helpful).

My favorite part of weightlifting is the experimentation required to achieve maximum results. So, even in light of these facts, I’ve toyed around with CO2 purging for the past two weeks. Right before the last few sets of my heavy lifts I’d hyperventilate a bit, just two or three quick and deep breathes. Then I’d take one deep breath and start the set. I haven’t made a quantitative study of the experiment but, qualitatively, purging felt helpful. When I used this technique I always seemed to reach the end of my set strong, sometimes even cramming in an extra rep. It probably had a lot to do with psychology; perhaps by beginning the lifting ritual a few seconds earlier I was more focused by the time I actually began to work. Or maybe breathing like a bull ready to gore something gave me a bit of an adrenaline pump. In any case, I got the result I desired and felt good doing it.

I wouldn’t recommend purging to anybody already prone to hyperventilation. And I wouldn’t recommend taking more than one or two quick breathes, lest you run the risks of CO2 deprivation. For instance, if you feel light-headed after you purge then you’re probably doing too much. All that being said, some light experimentation with purging isn’t going to kill you. Ultimately you’ve got to find the techniques that work best for you, and for that you’ve got to get creative.



  1. My dad and I used to do this when I was a kid. We’d hyperventilate a bit and see how many lengths of a pool we could swim without coming up for air. It definitely helped and my dad was pretty good at it. I never knew why it worked…

    Comment by jbraj — January 30, 2010 @ 3:11 pm

    • Cool. If Percy does it then there must be something to it. I still don’t know what to make of it, really, but I’m going to keep testing it for a bit.

      Comment by cfranc — January 30, 2010 @ 3:29 pm

  2. After seeing the same episode on tedtalks i also am curious of the benefits of c02 purging. I was researching it’s possible benefit to singing. This forum is the only result i found. Pretty cool

    Comment by Eelnitsud — March 4, 2011 @ 6:49 pm

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