And what about people like David Blaine or Tom Sietas? Sietas held his breath underwater for over 22 minutes (world record). I know they train for it like months and even years, but doesn’t holding your breath = no oxygen to brain?
Permanent brain damage apparently occurs just after 4 minutes of lack of oxygen to the brain, so why are freedivers left generally unscathed after 8 or 10 minutes without air?
In: Biology
In the simplest explanation: Holding your breath does NOT mean no oxygen to brain.
Oxygen doesn’t suddenly stop being transported to your brain just because you held your breath. Oxygen is held by the blood and transported to your brain. This is ongoing even when you hold your breath, it takes some time before all the stored oxygen in your blood is used up when you stop breathing and stop restoring oxygen to the blood.
Oxygen is transported to the brain through the blood. You suffer brain damage after there is NO oxygen being transported to it – which means all the oxygen stored in the blood has been used up. How much oxygen your blood is able to store and long it takes for your body to finish using all the stored oxygen is what affects how long you can hold your breath safely.
People train to be able to store more oxygen in their blood, and also use oxygen slower.
People who can hold their breath for 10+ minutes basically means the oxygen supply in their blood is enough for their brain to have access to oxygen for 10+ minutes BEFORE the oxygen runs out.
They breathe funny before diving to oxygenate their blood to an extreme level.
In other words they take some extra oxygen with them, bound to red blood cells, and have trained to use it sparingly.
Also 4-6 minutes is like most of those sort of specs, just an average, not a rule.
Your blood has oxygen in it.
Tonight’s homework, one page, double spaced about hemoglobin
There’s a super interesting video for this. If you’ve got an hour to spare I highly recommend you check out James Nestor. https://youtu.be/aH9boP9pksM
Adding to what other people said, only a minuscule amount of the oxygen in the air we breathe is used in the body. That’s why CPR works, there is still a significant amount of oxygen in exhaled breath that can be breathed into another person for oxygen.
So it takes a while until the body actually needs “fresh” oxygen/until it runs out.
Easy ELI5 boils down to one thing, adaptation. They’ve got factors working for them in their body plus they practiced a lot so their bodies adapted.
Everyone else has given great answers, but I’d like to give a simple analogy that may make sense.
We all know a car needs gas to run, just like the brain needs oxygen. Deprive an engine of gas, and it will eventually coast to a stop. If you’re in a moving car, and it runs out of gas, you only have a limited time before it stops moving. This is why cars have gas tanks.
The body is similar – divers take a whole lot of deep breaths before they dive, which is similar to a car filling up with gas. And when they dive, they use up the oxygen stored in their blood like a car uses up the gas in its tank.
The blood running out of oxygen is similar to the car running out of gas – once it’s gone, there’s a time limit. For a moving car that means coming to a stop, and for a human that means brain damage.
My dad smoked almost his whole life, starting from a very young age. In his 40s he could hold his breath under water for about 4 or 5 minutes. I’ll be 40 this year, never smoked a single cigarette and can only hold my breath under water for about a minute tops.
When you read that people cannot survive more than 4-6 minutes without oxygen, it means just that, zero oxygen in the body for that amount of time. It is also referring to normal situations. You can increase the oxygen level in your body by deep breathing. You can slow the exiting of oxygen from your body by slowing breathing and being very still. With practice you can get up to the numbers you mention. Also, some bodies are better and more suited to doing this feat. There are differences between people who are born and live in higher altitudes to those from lower altitudes.
Oxygen doesn’t travel faster than the speed of light. It diffuses through your body and takes time.
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