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Author Topic: How can the brain cope with the low oxygen experienced by free-divers?  (Read 7390 times)

Rich Vogt

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Rich Vogt asked the Naked Scientists:

Hello Naked Scientists!

I am a great fan of your show.  I'm a PhD student working in Montreal, Canada, and I listen to your show every week while working in the lab. 

I recently read an article about free diving, and was astonished to learn that champion divers can hold their breath for up to 6.5 minutes!  I understand that they can train their muscles to cope with the lack of oxygen, and that they are eventually able to reduce their resting heart rate to an impressive degree. 

What I was wondering is how the brain copes without oxygen for so long without becoming damaged, and if the brain can be trained in the same way to cope with apnea?
 
Thanks!

Richard

What do you think?
« Last Edit: 28/12/2009 12:35:07 by chris »


 

Offline Karen W.

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I have sleep apnea and this is a good question... I hope someone comes along who can shed some light on the question!
 

Offline Karen W.

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It seems to me that I was having lots of memory trouble as well a dysfunction in cognitive abilities having trouble keeping things straight and sometimes jumbled thoughts.. and with more uninterrupted sleep I have felt more mentally aware and able.. I really do believe this is due to the influx of air where previously I was not getting it... It was adding to deplete oxygen from my heart also which has reeked havoc with me.. My machine has helped me to think better during the day and feel less spacey. which is nice.. I am able to think more clearly for sure..

I would think , just my opinion that over time they might also suffer some cognitive disruptions that may be very mild or insignificant at first, but I would guess in the long run, may cause some cognitive damage!
 

Offline EatsRainbows

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kind of an old thread, but i know that athletes frequently train at high altitudes, this forces the body to produce more red blood cells which increases oxygen carrying capacity of the blood and thereby increases stamina under circumstances, such as heavy training, when oxygen cannot be supplied to the muscles fast enough.

People who live in the himalaya, for example, have no trouble whatsoever coping with low oxygen levels. Evidently their bodies are 'trained' to cope. They do not get symptoms of altitude sickness such as fluid build up in the lungs and swelling of the brain.

Another thought, I have  scuba diving license and i seem to recall my instructor saying something about free divers somehow 'tricking' their brain and lungs into thinking that oxygen levels are high enough by the repetitive short, fast breaths they take before diving. Im pretty sure that what forces us to feel the need to breath has to do with carbon dioxide levels in the blood being too high in contrast to oxygen levels, but somehow this breathing method fools the system and its actually very dangerous.

sorry thats a bit vague... but theres my two cents on the matter!
« Last Edit: 26/12/2009 03:21:10 by EatsRainbows »
 

Offline yor_on

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I think what you are thinking of when it comes to high altitude living is genetic differences Rainbow.
Something Something :) As for free diving, the brain seems to have enough neurons to survive for quite some time without us becoming noticeably 'different'. I'm sure there are cell death involved when you stay that long but the same could be said when you drink alcohol, both kill braincells.
« Last Edit: 27/12/2009 23:11:38 by yor_on »
 

Offline EatsRainbows

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I wonder if these genetic differences of high altitude dwellers could be a case of biological fitness as relative the environment? That is to say, i wonder if their physiology would be advantageous at a lower altitude also? Or perhaps there is some cell death or negative effects to these 'altitude survival' adaptations and it is merely advantageous in the given situation? I suppose that could likely be the case..... however i have read some references to high altitude dwelling and training being GOOD for ones health, humph   :-\

Regardless, it is true that athletes train at high altitudes as it does increase both haemoglobin levels and also the degree of lung expansion possible
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At altitude there is a decrease in oxygen hemoglobin saturation. In order to compensate for this, Erythropoietin (EPO), a hormone secreted by the kidneys, stimulates red blood cell production from bone marrow in order to increase hemoglobin saturation and oxygen delivery
http://en.wikipedia.org/wiki/Altitude_training

However:
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For example, it has been shown that athletes performing primarily anaerobic activity do not necessarily benefit from altitude training as they do not rely on oxygen to fuel their performances.
http://en.wikipedia.org/wiki/Altitude_training
But i couldn't see an explanation as to why. Surely if there is increased haemoglobin, the blood can therefore hold more oxygen, therefore the supply would continue to the brain for longer? Perhaps though, the quantity of oxygen in the blood does not offer any 'time' extension, only quantity increase within the same time? therefore it would not apply to free divers? does anyone know? I think i can say i am now confused!  ??? lol



This is what I was thinking of before:
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Before diving, performance-oriented freedivers hyperventilate to a certain degree, resulting in a lower level of CO2 in their lungs and bloodstream.[3] This postpones the start of stimulation to the breathing centre of the brain, and thus delays the warning signals of running out of air. As the oxygen level of the blood is not increased by hyperventilation, this is very dangerous and may contribute to shallow water blackout and deep water blackout
http://en.wikipedia.org/wiki/Free-diving
« Last Edit: 28/12/2009 03:13:53 by EatsRainbows »
 

Offline yor_on

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"There are two types of anaerobic energy systems: 1) the high energy phosphates, ATP adenosine triphosphate and CP creatine phosphate and, 2) anaerobic glycolysis.

The high energy phosphates are stored in very limited quantities within muscle cells.

Physical activities that last up to about thirty seconds rely primarily on the former, ATP-PC phosphagen, system. Beyond this time both aerobic and anaerobic glycolytic metabolic systems begin to predominate." Anaerobic_exercise

Yeah, free divers seems to play with death. I saw that they have people going down with them just to make sure that they don't drown down there. Some of the most advanced free divers seems to exist here in Sweden (Bathing with the polar bears one assumes?:)  Freediving
 

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