5 ms·

One reason Navy Seals need to be good at this is that they are swimming 50m underwater in one breath. When swimming while holding your breath, your brain is tel

One reason Navy Seals need to be good at this is that they are swimming 50m underwater in one breath. When swimming while holding your breath, your brain is telling you, stop, you're low on air, indeed, you can ignore than and swim the rest.

spearo77 11y ago
An interesting fact is that your brain has no idea how much oxygen you have left. What it can sense however, is a build up of CO2.
armitron 11y ago
The urge to breathe doesn't come because one is low on air, but due to CO2 buildup in the blood. Humans have no physiological detectors for blood oxygen levels, they can only detect CO2. Normally CO2 buildup response is calibrated to be "early" in terms of oxygen, but the calibration can change (e.g. through hyperventilation) which can lead to blackouts and drowning since blood oxygen levels can drop below ones needed to keep brain "on" before CO2 buildup response even registers. Ignoring the urge to breathe is definitely not a smart thing to do unsupervised unless one wants an early, watery grave. Your response is misleading in that it implies "mental toughness" (utter bollocks) or a skill that some people have more than others. If Navy Seals (or anyone else) do this for real, you can bet your ass they do it under strict supervision, when training/competing (e.g. BUDS).
- jo6gwb 11y ago
  There have been Navy SEALS who have died because of this: http://www.13newsnow.com/story/news/military/2015/04/24/incident-involving-special-forces-unit-at-little-creek-fort-story/26322507/ http://www.13newsnow.com/story/news/military/2015/04/24/inci...
jkot 11y ago
When swimming underwater, brain should not be telling or ignoring anything, it should be totally empty. Idle brain consumes about 25% oxygen, even more when it is being used.
- pc86 11y ago
  I would love to see a source for this that thinking about something uses more oxygen.
  - Phlarp 11y ago
    Just the act of thinking won't consume more oxygen, but thoughts can lead to physiological changes, like panic, that do consume more oxygen.
  - Phlarp 11y ago
    Just the act of thinking won't consume more oxygen, but thoughts can lead to physiological changes, like panic, that do consume more oxygen.
  - eric_h 11y ago
    a meditative state is definitely helpful in reducing the body's consumption of oxygen. I got my open water scuba certification many years ago from a former Navy SEAL. At the time, I was 4' 8" and weighed 85 pounds. The Navy SEAL was about 5' 10", 200 pounds. Every single dive we went on he used less than half the air that I used, and I used less air than the rest of the dive group (because I didn't need as much given my stature). He explained that he used a meditative style breathing pattern and simply remained very calm underwater. /anecdata
    - mapt 11y ago
      Your incorrect assumption is that you're supporting the same hardware with different software. Drastic changes occur with aerobic training and hypoxic stress in the red blood cell count & blood volume, blood pressure, heart stroke volume & lower resting heartrate. He has more muscles, more energy stored in glycogen in those muscles, and swims faster. The person you learned from was likely not physiologically capable of long dives when he first started, no matter his mentality. And nobody is capable of using a "meditative breathing pattern" while they're exerting themselves at the limit of their aerobic capabilities; He was farther from them than you were. There are likely other long-term adaptations we don't know about, specific to diving.

spearo77 11y ago

An interesting fact is that your brain has no idea how much oxygen you have left. What it can sense however, is a build up of CO2.

armitron 11y ago

The urge to breathe doesn't come because one is low on air, but due to CO2 buildup in the blood. Humans have no physiological detectors for blood oxygen levels, they can only detect CO2. Normally CO2 buildup response is calibrated to be "early" in terms of oxygen, but the calibration can change (e.g. through hyperventilation) which can lead to blackouts and drowning since blood oxygen levels can drop below ones needed to keep brain "on" before CO2 buildup response even registers. Ignoring the urge to breathe is definitely not a smart thing to do unsupervised unless one wants an early, watery grave. Your response is misleading in that it implies "mental toughness" (utter bollocks) or a skill that some people have more than others. If Navy Seals (or anyone else) do this for real, you can bet your ass they do it under strict supervision, when training/competing (e.g. BUDS).

jo6gwb 11y ago
There have been Navy SEALS who have died because of this: http://www.13newsnow.com/story/news/military/2015/04/24/incident-involving-special-forces-unit-at-little-creek-fort-story/26322507/ http://www.13newsnow.com/story/news/military/2015/04/24/inci...

jkot 11y ago

When swimming underwater, brain should not be telling or ignoring anything, it should be totally empty. Idle brain consumes about 25% oxygen, even more when it is being used.

pc86 11y ago
I would love to see a source for this that thinking about something uses more oxygen.
- Phlarp 11y ago
  Just the act of thinking won't consume more oxygen, but thoughts can lead to physiological changes, like panic, that do consume more oxygen.
- Phlarp 11y ago
  Just the act of thinking won't consume more oxygen, but thoughts can lead to physiological changes, like panic, that do consume more oxygen.
- eric_h 11y ago
  a meditative state is definitely helpful in reducing the body's consumption of oxygen. I got my open water scuba certification many years ago from a former Navy SEAL. At the time, I was 4' 8" and weighed 85 pounds. The Navy SEAL was about 5' 10", 200 pounds. Every single dive we went on he used less than half the air that I used, and I used less air than the rest of the dive group (because I didn't need as much given my stature). He explained that he used a meditative style breathing pattern and simply remained very calm underwater. /anecdata
  - mapt 11y ago
    Your incorrect assumption is that you're supporting the same hardware with different software. Drastic changes occur with aerobic training and hypoxic stress in the red blood cell count & blood volume, blood pressure, heart stroke volume & lower resting heartrate. He has more muscles, more energy stored in glycogen in those muscles, and swims faster. The person you learned from was likely not physiologically capable of long dives when he first started, no matter his mentality. And nobody is capable of using a "meditative breathing pattern" while they're exerting themselves at the limit of their aerobic capabilities; He was farther from them than you were. There are likely other long-term adaptations we don't know about, specific to diving.