Apnea Effects on the Brain

[Jimmy_Wales]

I recently became very interested in apnea training and obviously that led me to the free diving community. I have no plans to ever free dive but am fascinated with the mind-body control aspect of holding your breath.

Obviously blacking out underwater runs the risk of Hypoxic brain damage but I was wondering would any extended apnea have small effects on the brain? I've read that during breath holds, blood shunting keeps oxygen to the brain at a near normal constant. But to the layman it would appear that breath holds would obviously kill brain cells, they need oxygen to live right?

Does anyone have any insight on this?

 

[trux]

I've read that during breath holds, blood shunting keeps oxygen to the brain at a near normal constant. But to the layman it would appear that breath holds would obviously kill brain cells, they need oxygen to live right?

Does anyone have any insight on this?

You already answered your question yourself in the first sentence, so what exactly do you want to know more? If if is the mechanism, then look up the term "diving reflex" or "diving response" here on DB, or on the web.

It is more complex, but basically the brain is protected by the blood shunt as you have just written (thanks to periferal vasoconstriction), which then also avoids that the O2 in the blood is being spent by muscles or by non-vital organs. Then there is strong vasodilation of cerebral blood vessels, increase in blood pressue, increase of hematocrit (thanks to the contraction of the spleen), weaker affinity of hemoglobin to O2 (thanks to high CO2/low pH), allowing the brain to dip deeper into the stores and going safely into deeper desaturation, and several other effects.

Describing it all in details would take quite a bit of time, so I really recommend picking up some book about freediving, or browsing a bit the forum and the web for relevant information.

 

[Antoine]

Hi,
The New York Times published an article on the effects of regular breath-holding on people's brains.
The article quotes an Australian study where researches attempted to find whether breath-holding has any adverse impacts on the brain by conducting various tests on multiple freedivers. As far as I can remember, they did not find that frequent breath-holding had serious impacts on the functioning of the brain.
However, they do concede that they are still not entirely sure about the long-term impacts of breath-holding.
Here is the link:Is Breath-Holding Hazardous to Your Brain? - NYTimes.com
Hope this helps

 

[Kars]

It's lack of conclusion sounds like a plea for more research funding

 

[Antoine]

Yeh. But the main problem is that no one seems to have done any long term research...or mabey they have but are too scared to say to freedivers that according to research we'll all be kicking the bucket at below average ages from brain issues.:duh

 

[trux]

...or mabey they have but are too scared to say to freedivers that according to research we'll all be kicking the bucket at below average ages from brain issues.:duh

Yes, sure, just look at all those Japanese and Korean Ama divers who typically dive into their high 70's or even at 80 . Or check out the DB members like Bill Graham who dives the longer and deeper the older he is. The last time I remember he did 75m CWT on his 75 years. Hope we hear from him this year again with some PB.

 

[Kars]

Yes, sure, just look at all those Japanese and Korean Ama divers who typically dive into their high 70's or even at 80 . Or check out the DB members like Bill Graham who dives the longer and deeper the older he is. The last time I remember he did 75m CWT on his 75 years. Hope we hear from him this year again with some PB.

I would like to vote Bill Graham to be freediver of 2012!

 

[Antoine]

Those guys are amazing. Whilst at that age sadly many people are in nursing homes and have serious health problems, these guys get younger with age! I hope I'll be like them. I think, like many things in life and in freediving, its all about mental strength. Those who constantly persevere, those who never complain about getting old, those who never say never are those who live the longest and stay the fittest for the longest.

 

[TomW]

Hyperventillating before a dive is especially dangerous as the large change in ratio of O2:CO2 causes a change in the pH of the blood which in turn causes a constricting of the capillaries in the brain. This is the reason for dizziness, black-outs or incoherence during excessive deep-breathing/hyperventilation. Especially when coupled with any form of exertion or strain of a dive, it will lead to a greater risk of loss of consciousness or other problems while underwater.

 

[Antoine]

Freediving clearly can have some immidiate impacts on the brain functioning such as black-outs, confusion...etc However, what is still mostly unknown are the long-term impacts on the brain.