10 ms·

Pushing the Limits of Extreme Breath-Holding

73 points by uptown 9y ago

poster123 9y ago
How is this anything other than dangerous and stupid?
- imglorp 9y ago
  For static apnea, I think they're talking about laying on the surface of a shallow pool with a spotter standing next to them. The free diving--where they do this at depth--is what kills people.
  - jobigoud 9y ago
    I'm curious, what does the spotter do? How does one know there is a problem? I assume at high levels the competitors are able to lower their metabolism and heart rate, etc. What are alert signs, are they monitoring brain activity?
    - mogoman 9y ago
      Generally you lie in the water in a wetsuit for buoyancy. The spotter holds on to you to make sure you don't float out to sea (in our case). They also check on you by prompting you to give an "okay" indication (by lifting a finger every 30 seconds or so). One danger of being under water is that you can pass out even after you've taken a breath of fresh air, so the spotter also is there to make sure you are good in the few seconds after you come up.
  - fabrice_d 9y ago
    What kills people is inadequate security measures, not depth diving vs. static apnea in a pool. There have been very few (I think only one) deaths during freediving competitions, where protocols are used to guarantee the security of the athletes. Remember that you don't die of a black out, you die of drowning because you inhale water during a black out. As said in another comment, the black out is a protective mechanism when you run low on oxygen, but the breathing reflex is triggered by high CO2. Freedivers train both to sustain low oxygen (by doing long breath holds) and high CO2 (by doing repeats of shorter ones). Monitoring a static apnea is pretty simple if you just pay close attention: when a black out happens, the diver will usually release a lot of air for instance, and pulling them out of water before they drown is what you do. Then you slap them to wake them up :) In open water competitions, these days divers are tethered to the dive line, announce their target depth and can't go past it. They also announce an expected dive time which is used to plan the start of the safety divers. These safety divers escort the athlete on the end of the dive up (sometimes, as deep as from 30m), staying close enough to grab them if needed, but never touching them (that would disqualify as assistance). There is also a counter weight in place to bring up everything quickly in case something goes wrong deep. Issues are usually happening close to the surface (let's say in the last 10-15m); deep blackouts are very rare and usually a consequence of other problems like being disoriented if you get a ruptured eardrum. Recreative freediving is a wonderful activity with very little risk if you just use a buddy system and don't push the limits beyond what both of you can do. It's good for you body and your mind!
    - YeGoblynQueenne 9y ago
      The problem is that you can't hold your breath if you black out. So if you black out while submerged you're in grave danger, even more so if you're some 30m down (then you're as good as dead). Even if you have a buddy while this happens and they manage to grab you and drag you out instantly, then start CPR the moment you're on the surface there's nothing guaranteeing you're going to survive.
      - apetrov 9y ago
        Actually the rescue procedure is straightforward https://www.deeperblue.com/rescue-procedures-for-freediver-black-out/ https://www.deeperblue.com/rescue-procedures-for-freediver-b... so if there is a trained buddy watching your back you gonna be fine. PS you don't need CPR to recover from blackout.
        YeGoblynQueenne 9y ago
        That link literally says exactly what my comment says. That if you black out on the surface, then, OK, but if you black out in the water then laryngospasm will protect you from inhaling water for a bit (under a minute), but then it will end, at which point you'll inhale water and CPR will become even harder. etc. etc.
        fabrice_d 9y ago
        Sure, but if you have a buddy, a minute is more than enough for a rescue. I did it a couple of times from about 10m and it is a bit stressful but I got free beers in the end :)
        YeGoblynQueenne 9y ago
        Sounds like fun. Maybe drown-and-get-rescued should be introduced as a new sport.
        YeGoblynQueenne 9y ago
- DuckyC 9y ago
  Didn't you read the part where they compare it to any other sport? “Apnea is not different from many other sports, in the sense that practice at a high level often leads to deleterious impacts on human physiology,” he said. “Think about alpinists going to Mount Everest, climbers, gymnastics, marathon runners—every sport has its drawbacks when performed at the élite level.”
  - nmeofthestate 9y ago
    Yes, I thought that was smugly dismissive of the fact that these guys were brain damaged. In more mainstream sports where brain damage is a problem, it at least isn't met with "meh".
    - YeGoblynQueenne 9y ago
      For a list of examples, mostly contact sports, see the Wikipedia article on Chronic Traumatic Encephalopathy: https://en.wikipedia.org/wiki/Chronic_traumatic_encephalopathy https://en.wikipedia.org/wiki/Chronic_traumatic_encephalopat... Most documented cases have occurred in athletes involved in contact sports such as American football, wrestling, ice hockey, rugby, and soccer.[1] Other risk factors include being in the military, prior domestic violence, and repeated banging of the head.[1]
      - Stratoscope 9y ago
        Mobile friendly quote: > Most documented cases have occurred in athletes involved in contact sports such as American football, wrestling, ice hockey, rugby, and soccer.[1] Other risk factors include being in the military, prior domestic violence, and repeated banging of the head.[1]
      - pmoriarty 9y ago
        "Traumatic" is the key word there. There are different sorts of brain damage, and traumatic brain damage (the kind from impact) is only one kind. I am not a doctor, but I wouldn't be surprised if brain damage due to hypoxia (low levels of oxygen in the brain) is not considered "traumatic" brain damage, and so wouldn't be on that list.
- xutopia 9y ago
  I did 3m06s in a pool, very much like those apnea competitions. I had a spotter and people around me in case something went wrong. For me the idea of controlling my body and mind to do such a feat felt like a huge accomplishment. It requires fighting off reflexes, relaxing my muscles and reducing my thoughts to the bare minimum so as to use the least oxygen possible. Control and determination are tested and it feels great to overcome these things. I stopped practicing apnea because I didn't have any data on how it could affect my brain negatively but I still am very proud of my accomplishment. Also before I started I couldn't swim a full lap underwater without coming up for air but now I can do it without any problem.
  - postsantum 9y ago
    It seems Guillaume Néry's career haven't damaged his brain. Of course, this is a single data point, but he has been freediving for twenty years https://www.deeperblue.com/what-does-a-freedivers-brain-look-like/ https://www.deeperblue.com/what-does-a-freedivers-brain-look...
  - xyhopguy 9y ago
    used to do this during swim practice. unbelievably relaxing and amazing how far you can swim without a breath with a slow buildup. we used to go up to 4 lengths aka 100m
    - 0xdeadbeefbabe 9y ago
      What stroke? Seems like you'd choose a minimal stroke.
      - fabrice_d 9y ago
        If you are without fins, a long relaxed breaststroke is what you do.
      - xyhopguy 9y ago
        just freestyle, nice and relaxed. swimming distance isnt the best measure though, some people are more/less efficient than others.
- YeGoblynQueenne 9y ago
  Freediving is actually a lot of fun. I freedive with flippers in the summer and I could probably do twice as well in duration and distance if I really tried- but I'm always worried I might pass out underwater and die in the middle of a dive. And that woulnd't be very fun, now would it? There's lots of recreational activities like that that people start doing because they're very pleasant, then they start getting all competitive about them and take it all to extremes where the only reward is knowing you can beat the competition. That's kind of sad, really, and completely misses the point of doing something for enjoyment. But I guess it's the prevailing culture. We value being the best at something more than we value life itself.
  - indubitable 9y ago
    You don't find it ironic in that you're judging people for what they find enjoyable and arguing it misses the point of doing something for enjoyment? I receive immense pleasure and enjoyment in improving at things -- something I assume is probably an evolutionary imperative. Bettering ourselves is fun. Competing is fun. Bettering ourselves while competing is absurdly fun.
    - YeGoblynQueenne 9y ago
      Fun is one thing. Dangerous is another. Edit: btw, I think it's fine to "judge" people. My judgement, if that's what it is, can't really affect anyone's life, or actions and they're not even addressed to any particular individual. You might even say they're actually my, you know- opinions.
      - indubitable 9y ago
        Sure, but in reality opinions are the one thing we ought scrutinize the most, right? Facts are either true or false, but are unchanging at given any moment in time. Opinions are not necessarily true or false, but can and arguably should constantly change. So perhaps seeing things from anothers eyes might lead you to consider your own opinion in another way. And if not then of course that's also fine. To each their own!
- kls 9y ago
  Personally I don't consider it either, it's humans pushing the edge of what is humanly possibly which is something we always do. It's what makes us unique. That being said, static apnea is actually pretty safe, there is a spotter with the person the whole time. Competition free diving is fairly safe as well, as they have divers stationed at different depths who spot for black out and have spare air. I don't freedive, but given that I am an avid spearfisher I do apnea training to hit deeper depths and to be able to hunt longer at depth. It is probably the most dangerous of any of the apnea related sports but still relatively safe if you do it correctly, which means having a inflatable buoyancy device, a knife and practicing one down 2 up where one diver goes down, another follows down half way a minute later and one stay at the surface as a spotter. Not only does this provide aid in the event of a blackout but it also provides spotters for sharks. Another issue with safety is setting a reasonable limit, in static apnea in a pool I can hold for over 5 minutes, but when I am spearfishing I set my clock to 4 minutes, 3 if I am going to 100ft or deeper no matter what is going on, when the time runs out I am surface bound. Once trained it easy to ignore hypoxia and spend another 30 seconds chasing a fish but that can be the difference between life and death. The average human can hold enough oxygen in their lungs to stay conscious for over 6 minutes, the CO2 reflex is what get's them, so if one keeps their dive below 4 minutes as a safety margin the chances of black out are minimized significantly. It becomes dangerous and stupid when people start to throw away those safety mechanisms in a quest to cut corners and push further. A good example is we where diving a wreck last summer, I was at about 70ft, my cousin was down to 45 2 minutes after I went down. I lined up on a huge Pompano and it started swimming away from me, I pursued for about 20 seconds and it had stopped and turned broadside to me, I needed to close 30 ft. to take the shot but I was already past the 4 minute mark by a few seconds. When you are in that situation it's easy to get tunnel vision on the goal and go for it, but then if the fish moves again you are in this game of just a few more seconds. Anyways, I broke off, flagged my cousin to descendand showed him where the fish was, I went up, took the spotter position, the spotter depended to 45 and I took the spotter position on the surface. My cousin ended up with a prize Pompano and bragging rights, but we all got to ride home on the boat and listen to him go on and on about lining up the shot, at that's the point with proper safety procedures everyone get's to enjoy the ride home.
  - lovemenot 9y ago
- YeGoblynQueenne 9y ago
  It gets worse: Competitive diving: During competitions in breath-hold diving, most divers hyperventilate extensively and determine the duration of their breath-hold by means other than the hypercapnic ventilatory drive. Some seem to react to hypoxia via the urge to breathe, while others actively decide to abort the breath-hold when vision starts to falter, described as 'greyout' (personal communication with elite divers). From: https://www.diversalertnetwork.org/files/UHMS_DAN_2006_Breath-hold_Workshop_Proceedings.pdf https://www.diversalertnetwork.org/files/UHMS_DAN_2006_Breat... (Chapter 2, Physiological mechanisms involved in the risk of loss of consciousness during breath-hold diving; pg 27).
nickpsecurity 9y ago
Here's a Popular Science article I read a long time ago on this where the author gets to experience free diving: https://www.popsci.com/scitech/article/2003-06/one-dive-one-breath https://www.popsci.com/scitech/article/2003-06/one-dive-one-... Although, my first exposure to the topic was a movie called The Big Blue about a free diver pushing himself to and past his limits. Had Jean Reno in it. Just found out it was Luc Besson's movie, too. https://www.youtube.com/watch?v=82onGmBx9ZM https://www.youtube.com/watch?v=82onGmBx9ZM
- dmitriid 9y ago
  I remember holding my breath when watching that movie. Thank you for reminding about it!
matt_wulfeck 9y ago
> Blaine’s trick was to breathe pure oxygen prior to his demonstration, delaying the point at which his blood chemistry went critical. You can do something like this yourself! This used to be one of my favorite pool tricks when younger at the pool with friends. Simply hyperventilate for ten or fifteen seconds then go for it. You’ll be amazed how easy it is to stay under water for a few minutes.
- gyrgtyn 9y ago
  That's how you pass out
  - mason55 9y ago
    That's how you drown. The feeling you get when you're running out of air is not because you are low on oxygen, it's because you have too much CO2. By hyperventilating you lower your CO2 levels to a point where you can run out of oxygen before you start to feel that suffocation response. Then you pass out underwater and quietly die before anyone realizes you're gone. Here's a good graph showing what happens: https://en.wikipedia.org/wiki/Freediving_blackout#Shallow_water_blackout https://en.wikipedia.org/wiki/Freediving_blackout#Shallow_wa...
- mannykannot 9y ago
  This is a dangerous practice when free diving. One non-intuitive risk is that as you ascend, the partial pressure of the remaining oxygen in your lungs decreases on account of the reducing pressure, and this can lead to a shallow-water blackout. While the decreasing partial pressure happens with or without hyperventilating, the risk is much greater if you have been able to extend your dive and draw down your oxygen reserve. Hyperventilating does not significantly increase your oxygen saturation, which is around 98% if you are healthy, and it does not add more oxygen in your lungs; its effect is to decrease your CO2 concentration, suppressing the involuntary breathing reflex. http://freediveuk.com/the-dangers-of-hyperventilation-when-freediving/ http://freediveuk.com/the-dangers-of-hyperventilation-when-f...
- pacaro 9y ago
  The normal consensus in the free diving community is that meditation is more effective that hyperventilating, there is more to gain by reducing your heart rate than by increasing the amount of oxygen in your blood, hyperventilating tends to raise the heart rate In my experience most people can hold their breath for about a minute if they push out of their comfort zone and, with a modicum of practice, three minutes is attainable. For me, being able to hold my breath for three minutes while doing nothing, translates to being able to swim underwater for nearly a minute, or reach a depth of about 45’ without weights.
kazinator 9y ago
The record is held by the first homo sapiens who asphyxiated. Tens of thousands of years and counting!
clort 9y ago
I'm a bit confused by the breath-hold where they breathed pure oxygen. The article claims that because they only started with oxygen in their lungs, that is all absorbed and nothing left by the end. But, where does the carbon dioxide go in this case? Your body is producing it, and it normally transitions from the blood into the lungs, to be exhaled. why doesn't it do that if there is only oxygen in there?
- thope 9y ago
  Correct me if I'm wrong, but maybe the carbon dioxide you exhale comes from the air you inhale. No air in, no carbon dioxide out.
  - jdblair 9y ago
    Correction: https://en.wikipedia.org/wiki/Respiration_(physiology) https://en.wikipedia.org/wiki/Respiration_(physiology)
    - thope 9y ago
      Ok thank you, I also found a short answer[0]. It seems the carbon comes from the conversion of glucose; that is, from food. [0] http://www.smh.com.au/news/big-questions/we-breath-in-oxygen-and-breath-out-carbon-dioxide-where-does-thecarbon-come-from/2008/06/06/1212259085199.html http://www.smh.com.au/news/big-questions/we-breath-in-oxygen...
  - jjoonathan 9y ago
    Your metabolism looks like a combustion process: O2 + hydrocarbons -> CO2 + H2O. The carbon comes from food you ate. If you aren't breathing out CO2, you're either not metabolizing or you're storing the "burned" carbon in an undesirable metabolic byproduct (e.g. lactic acid).
AElsinore77 9y ago
This is quite interesting -- tangentially related, is anyone aware of studies of the long term effects of sports which include blood chokes (constricting carotids)? These might include Judo, Brazilian Jiu Jitsu, as well as modern MMA and submission grappling. In these cases, there may be plenty of oxygen in the blood, but the blood flow to the brain is being restricted causing loss of consciousness.
tasty_freeze 9y ago
One thing I find fascinating is that when you hold your breath long enough and your body is forcing you to breath, your lungs still hold plenty of oxygen. If you exhaled into an empty bag, then inhaled that air back into your lungs, that reflex would be quelled for awhile. Of course after each cycle the O2 content would drop an CO2 would rise and the period of each cycle would get shorter.

73 points by uptown 9y ago

poster123 9y ago

How is this anything other than dangerous and stupid?

imglorp 9y ago
For static apnea, I think they're talking about laying on the surface of a shallow pool with a spotter standing next to them. The free diving--where they do this at depth--is what kills people.
- jobigoud 9y ago
  I'm curious, what does the spotter do? How does one know there is a problem? I assume at high levels the competitors are able to lower their metabolism and heart rate, etc. What are alert signs, are they monitoring brain activity?
  - mogoman 9y ago
    Generally you lie in the water in a wetsuit for buoyancy. The spotter holds on to you to make sure you don't float out to sea (in our case). They also check on you by prompting you to give an "okay" indication (by lifting a finger every 30 seconds or so). One danger of being under water is that you can pass out even after you've taken a breath of fresh air, so the spotter also is there to make sure you are good in the few seconds after you come up.
- fabrice_d 9y ago
  What kills people is inadequate security measures, not depth diving vs. static apnea in a pool. There have been very few (I think only one) deaths during freediving competitions, where protocols are used to guarantee the security of the athletes. Remember that you don't die of a black out, you die of drowning because you inhale water during a black out. As said in another comment, the black out is a protective mechanism when you run low on oxygen, but the breathing reflex is triggered by high CO2. Freedivers train both to sustain low oxygen (by doing long breath holds) and high CO2 (by doing repeats of shorter ones). Monitoring a static apnea is pretty simple if you just pay close attention: when a black out happens, the diver will usually release a lot of air for instance, and pulling them out of water before they drown is what you do. Then you slap them to wake them up :) In open water competitions, these days divers are tethered to the dive line, announce their target depth and can't go past it. They also announce an expected dive time which is used to plan the start of the safety divers. These safety divers escort the athlete on the end of the dive up (sometimes, as deep as from 30m), staying close enough to grab them if needed, but never touching them (that would disqualify as assistance). There is also a counter weight in place to bring up everything quickly in case something goes wrong deep. Issues are usually happening close to the surface (let's say in the last 10-15m); deep blackouts are very rare and usually a consequence of other problems like being disoriented if you get a ruptured eardrum. Recreative freediving is a wonderful activity with very little risk if you just use a buddy system and don't push the limits beyond what both of you can do. It's good for you body and your mind!
  - YeGoblynQueenne 9y ago
    The problem is that you can't hold your breath if you black out. So if you black out while submerged you're in grave danger, even more so if you're some 30m down (then you're as good as dead). Even if you have a buddy while this happens and they manage to grab you and drag you out instantly, then start CPR the moment you're on the surface there's nothing guaranteeing you're going to survive.
    - apetrov 9y ago
      Actually the rescue procedure is straightforward https://www.deeperblue.com/rescue-procedures-for-freediver-black-out/ https://www.deeperblue.com/rescue-procedures-for-freediver-b... so if there is a trained buddy watching your back you gonna be fine. PS you don't need CPR to recover from blackout.
      - YeGoblynQueenne 9y ago
        That link literally says exactly what my comment says. That if you black out on the surface, then, OK, but if you black out in the water then laryngospasm will protect you from inhaling water for a bit (under a minute), but then it will end, at which point you'll inhale water and CPR will become even harder. etc. etc.
        fabrice_d 9y ago
        Sure, but if you have a buddy, a minute is more than enough for a rescue. I did it a couple of times from about 10m and it is a bit stressful but I got free beers in the end :)
        YeGoblynQueenne 9y ago
        Sounds like fun. Maybe drown-and-get-rescued should be introduced as a new sport.
        YeGoblynQueenne 9y ago
DuckyC 9y ago
Didn't you read the part where they compare it to any other sport? “Apnea is not different from many other sports, in the sense that practice at a high level often leads to deleterious impacts on human physiology,” he said. “Think about alpinists going to Mount Everest, climbers, gymnastics, marathon runners—every sport has its drawbacks when performed at the élite level.”
- nmeofthestate 9y ago
  Yes, I thought that was smugly dismissive of the fact that these guys were brain damaged. In more mainstream sports where brain damage is a problem, it at least isn't met with "meh".
  - YeGoblynQueenne 9y ago
    For a list of examples, mostly contact sports, see the Wikipedia article on Chronic Traumatic Encephalopathy: https://en.wikipedia.org/wiki/Chronic_traumatic_encephalopathy https://en.wikipedia.org/wiki/Chronic_traumatic_encephalopat... Most documented cases have occurred in athletes involved in contact sports such as American football, wrestling, ice hockey, rugby, and soccer.[1] Other risk factors include being in the military, prior domestic violence, and repeated banging of the head.[1]
    - Stratoscope 9y ago
      Mobile friendly quote: > Most documented cases have occurred in athletes involved in contact sports such as American football, wrestling, ice hockey, rugby, and soccer.[1] Other risk factors include being in the military, prior domestic violence, and repeated banging of the head.[1]
    - pmoriarty 9y ago
      "Traumatic" is the key word there. There are different sorts of brain damage, and traumatic brain damage (the kind from impact) is only one kind. I am not a doctor, but I wouldn't be surprised if brain damage due to hypoxia (low levels of oxygen in the brain) is not considered "traumatic" brain damage, and so wouldn't be on that list.
xutopia 9y ago
I did 3m06s in a pool, very much like those apnea competitions. I had a spotter and people around me in case something went wrong. For me the idea of controlling my body and mind to do such a feat felt like a huge accomplishment. It requires fighting off reflexes, relaxing my muscles and reducing my thoughts to the bare minimum so as to use the least oxygen possible. Control and determination are tested and it feels great to overcome these things. I stopped practicing apnea because I didn't have any data on how it could affect my brain negatively but I still am very proud of my accomplishment. Also before I started I couldn't swim a full lap underwater without coming up for air but now I can do it without any problem.
- postsantum 9y ago
  It seems Guillaume Néry's career haven't damaged his brain. Of course, this is a single data point, but he has been freediving for twenty years https://www.deeperblue.com/what-does-a-freedivers-brain-look-like/ https://www.deeperblue.com/what-does-a-freedivers-brain-look...
- xyhopguy 9y ago
  used to do this during swim practice. unbelievably relaxing and amazing how far you can swim without a breath with a slow buildup. we used to go up to 4 lengths aka 100m
  - 0xdeadbeefbabe 9y ago
    What stroke? Seems like you'd choose a minimal stroke.
    - fabrice_d 9y ago
      If you are without fins, a long relaxed breaststroke is what you do.
    - xyhopguy 9y ago
      just freestyle, nice and relaxed. swimming distance isnt the best measure though, some people are more/less efficient than others.
YeGoblynQueenne 9y ago
Freediving is actually a lot of fun. I freedive with flippers in the summer and I could probably do twice as well in duration and distance if I really tried- but I'm always worried I might pass out underwater and die in the middle of a dive. And that woulnd't be very fun, now would it? There's lots of recreational activities like that that people start doing because they're very pleasant, then they start getting all competitive about them and take it all to extremes where the only reward is knowing you can beat the competition. That's kind of sad, really, and completely misses the point of doing something for enjoyment. But I guess it's the prevailing culture. We value being the best at something more than we value life itself.
- indubitable 9y ago
  You don't find it ironic in that you're judging people for what they find enjoyable and arguing it misses the point of doing something for enjoyment? I receive immense pleasure and enjoyment in improving at things -- something I assume is probably an evolutionary imperative. Bettering ourselves is fun. Competing is fun. Bettering ourselves while competing is absurdly fun.
  - YeGoblynQueenne 9y ago
    Fun is one thing. Dangerous is another. Edit: btw, I think it's fine to "judge" people. My judgement, if that's what it is, can't really affect anyone's life, or actions and they're not even addressed to any particular individual. You might even say they're actually my, you know- opinions.
    - indubitable 9y ago
      Sure, but in reality opinions are the one thing we ought scrutinize the most, right? Facts are either true or false, but are unchanging at given any moment in time. Opinions are not necessarily true or false, but can and arguably should constantly change. So perhaps seeing things from anothers eyes might lead you to consider your own opinion in another way. And if not then of course that's also fine. To each their own!
kls 9y ago
Personally I don't consider it either, it's humans pushing the edge of what is humanly possibly which is something we always do. It's what makes us unique. That being said, static apnea is actually pretty safe, there is a spotter with the person the whole time. Competition free diving is fairly safe as well, as they have divers stationed at different depths who spot for black out and have spare air. I don't freedive, but given that I am an avid spearfisher I do apnea training to hit deeper depths and to be able to hunt longer at depth. It is probably the most dangerous of any of the apnea related sports but still relatively safe if you do it correctly, which means having a inflatable buoyancy device, a knife and practicing one down 2 up where one diver goes down, another follows down half way a minute later and one stay at the surface as a spotter. Not only does this provide aid in the event of a blackout but it also provides spotters for sharks. Another issue with safety is setting a reasonable limit, in static apnea in a pool I can hold for over 5 minutes, but when I am spearfishing I set my clock to 4 minutes, 3 if I am going to 100ft or deeper no matter what is going on, when the time runs out I am surface bound. Once trained it easy to ignore hypoxia and spend another 30 seconds chasing a fish but that can be the difference between life and death. The average human can hold enough oxygen in their lungs to stay conscious for over 6 minutes, the CO2 reflex is what get's them, so if one keeps their dive below 4 minutes as a safety margin the chances of black out are minimized significantly. It becomes dangerous and stupid when people start to throw away those safety mechanisms in a quest to cut corners and push further. A good example is we where diving a wreck last summer, I was at about 70ft, my cousin was down to 45 2 minutes after I went down. I lined up on a huge Pompano and it started swimming away from me, I pursued for about 20 seconds and it had stopped and turned broadside to me, I needed to close 30 ft. to take the shot but I was already past the 4 minute mark by a few seconds. When you are in that situation it's easy to get tunnel vision on the goal and go for it, but then if the fish moves again you are in this game of just a few more seconds. Anyways, I broke off, flagged my cousin to descendand showed him where the fish was, I went up, took the spotter position, the spotter depended to 45 and I took the spotter position on the surface. My cousin ended up with a prize Pompano and bragging rights, but we all got to ride home on the boat and listen to him go on and on about lining up the shot, at that's the point with proper safety procedures everyone get's to enjoy the ride home.
- lovemenot 9y ago
YeGoblynQueenne 9y ago
It gets worse: Competitive diving: During competitions in breath-hold diving, most divers hyperventilate extensively and determine the duration of their breath-hold by means other than the hypercapnic ventilatory drive. Some seem to react to hypoxia via the urge to breathe, while others actively decide to abort the breath-hold when vision starts to falter, described as 'greyout' (personal communication with elite divers). From: https://www.diversalertnetwork.org/files/UHMS_DAN_2006_Breath-hold_Workshop_Proceedings.pdf https://www.diversalertnetwork.org/files/UHMS_DAN_2006_Breat... (Chapter 2, Physiological mechanisms involved in the risk of loss of consciousness during breath-hold diving; pg 27).

nickpsecurity 9y ago

Here's a Popular Science article I read a long time ago on this where the author gets to experience free diving: https://www.popsci.com/scitech/article/2003-06/one-dive-one-breath https://www.popsci.com/scitech/article/2003-06/one-dive-one-... Although, my first exposure to the topic was a movie called The Big Blue about a free diver pushing himself to and past his limits. Had Jean Reno in it. Just found out it was Luc Besson's movie, too. https://www.youtube.com/watch?v=82onGmBx9ZM https://www.youtube.com/watch?v=82onGmBx9ZM

dmitriid 9y ago
I remember holding my breath when watching that movie. Thank you for reminding about it!

matt_wulfeck 9y ago

> Blaine’s trick was to breathe pure oxygen prior to his demonstration, delaying the point at which his blood chemistry went critical. You can do something like this yourself! This used to be one of my favorite pool tricks when younger at the pool with friends. Simply hyperventilate for ten or fifteen seconds then go for it. You’ll be amazed how easy it is to stay under water for a few minutes.

gyrgtyn 9y ago
That's how you pass out
- mason55 9y ago
  That's how you drown. The feeling you get when you're running out of air is not because you are low on oxygen, it's because you have too much CO2. By hyperventilating you lower your CO2 levels to a point where you can run out of oxygen before you start to feel that suffocation response. Then you pass out underwater and quietly die before anyone realizes you're gone. Here's a good graph showing what happens: https://en.wikipedia.org/wiki/Freediving_blackout#Shallow_water_blackout https://en.wikipedia.org/wiki/Freediving_blackout#Shallow_wa...
mannykannot 9y ago
This is a dangerous practice when free diving. One non-intuitive risk is that as you ascend, the partial pressure of the remaining oxygen in your lungs decreases on account of the reducing pressure, and this can lead to a shallow-water blackout. While the decreasing partial pressure happens with or without hyperventilating, the risk is much greater if you have been able to extend your dive and draw down your oxygen reserve. Hyperventilating does not significantly increase your oxygen saturation, which is around 98% if you are healthy, and it does not add more oxygen in your lungs; its effect is to decrease your CO2 concentration, suppressing the involuntary breathing reflex. http://freediveuk.com/the-dangers-of-hyperventilation-when-freediving/ http://freediveuk.com/the-dangers-of-hyperventilation-when-f...
pacaro 9y ago
The normal consensus in the free diving community is that meditation is more effective that hyperventilating, there is more to gain by reducing your heart rate than by increasing the amount of oxygen in your blood, hyperventilating tends to raise the heart rate In my experience most people can hold their breath for about a minute if they push out of their comfort zone and, with a modicum of practice, three minutes is attainable. For me, being able to hold my breath for three minutes while doing nothing, translates to being able to swim underwater for nearly a minute, or reach a depth of about 45’ without weights.

kazinator 9y ago

The record is held by the first homo sapiens who asphyxiated. Tens of thousands of years and counting!

clort 9y ago

I'm a bit confused by the breath-hold where they breathed pure oxygen. The article claims that because they only started with oxygen in their lungs, that is all absorbed and nothing left by the end. But, where does the carbon dioxide go in this case? Your body is producing it, and it normally transitions from the blood into the lungs, to be exhaled. why doesn't it do that if there is only oxygen in there?

thope 9y ago
Correct me if I'm wrong, but maybe the carbon dioxide you exhale comes from the air you inhale. No air in, no carbon dioxide out.
- jdblair 9y ago
  Correction: https://en.wikipedia.org/wiki/Respiration_(physiology) https://en.wikipedia.org/wiki/Respiration_(physiology)
  - thope 9y ago
    Ok thank you, I also found a short answer[0]. It seems the carbon comes from the conversion of glucose; that is, from food. [0] http://www.smh.com.au/news/big-questions/we-breath-in-oxygen-and-breath-out-carbon-dioxide-where-does-thecarbon-come-from/2008/06/06/1212259085199.html http://www.smh.com.au/news/big-questions/we-breath-in-oxygen...
- jjoonathan 9y ago
  Your metabolism looks like a combustion process: O2 + hydrocarbons -> CO2 + H2O. The carbon comes from food you ate. If you aren't breathing out CO2, you're either not metabolizing or you're storing the "burned" carbon in an undesirable metabolic byproduct (e.g. lactic acid).

AElsinore77 9y ago

This is quite interesting -- tangentially related, is anyone aware of studies of the long term effects of sports which include blood chokes (constricting carotids)? These might include Judo, Brazilian Jiu Jitsu, as well as modern MMA and submission grappling. In these cases, there may be plenty of oxygen in the blood, but the blood flow to the brain is being restricted causing loss of consciousness.

tasty_freeze 9y ago

One thing I find fascinating is that when you hold your breath long enough and your body is forcing you to breath, your lungs still hold plenty of oxygen. If you exhaled into an empty bag, then inhaled that air back into your lungs, that reflex would be quelled for awhile. Of course after each cycle the O2 content would drop an CO2 would rise and the period of each cycle would get shorter.