Hi Lydia. Surprising as it may seem with the slightest bit of training you can hold your breath a lot longer than you think. It isn't overly pleasant at first but you do get better at it over time and get more used to the sensations. The first thing to probably mention is that the unpleasant contractions that most people associate with really needing to breath are not caused by low oxygen but rather high carbon dioxide. It's a warning system of course developed over time through evolution which is there to encourage us to breath but it's not directly associated to critically low oxygen levels (low oxygen levels have little warning - you pass out which is of course not a good thing to a freediver so you do have to take the contractions seriously but with training you can go further. Secondly is being as efficient as possible. When underwater you'll see most good freedivers trying to be as efficient as possible. In competitive deep freediving once they achieve negative buoyancy (normally between 20 - 30 metres for an unweighted diver, shallower for those who are) they will relax and go into the glide or freefall stage of their descent. The idea is to move as little as possible because contracting muscles of course consumes oxygen. Even generally swimming around the more relaxed you can be, the longer you can stay down. Thirdly is something we call the mammalian dive reflex or MDR. This is particularly evident in swimming mammals like whales or dolphins when they descend, sometimes in the case of the sperm whale to extremely deep depths and stay there for quite long periods. Not just minutes but 10's of minutes. Their MDR kicks in which slows the heart beat even more and causes a few more physiological reflexes all of which aid it's ability to be more efficient without oxygen. All mammals actually have this reflex although it is more developed with whales in particular. We have it too and immersion in water of the face helps switch it on. If it's cold water then the effect is even more pronounced with some of the nerves in our facial area. That's just some of the reasons. You'll find some discussions about this online, particularly on freediving channels if it interests you. If you are interested in learning more then I recommend doing a freediving course through organisations such as SSI, AIDA or Apnea Australia (if you live in our part of the world). Thanks for the compelling question:).
Early in 2013 we went to Port Willunga to freedive the historic shipwreck the Star of Greece
How can people hold their breath for so long?! :O
Hi Lydia. Surprising as it may seem with the slightest bit of training you can hold your breath a lot longer than you think. It isn't overly pleasant at first but you do get better at it over time and get more used to the sensations. The first thing to probably mention is that the unpleasant contractions that most people associate with really needing to breath are not caused by low oxygen but rather high carbon dioxide. It's a warning system of course developed over time through evolution which is there to encourage us to breath but it's not directly associated to critically low oxygen levels (low oxygen levels have little warning - you pass out which is of course not a good thing to a freediver so you do have to take the contractions seriously but with training you can go further.
Secondly is being as efficient as possible. When underwater you'll see most good freedivers trying to be as efficient as possible. In competitive deep freediving once they achieve negative buoyancy (normally between 20 - 30 metres for an unweighted diver, shallower for those who are) they will relax and go into the glide or freefall stage of their descent. The idea is to move as little as possible because contracting muscles of course consumes oxygen. Even generally swimming around the more relaxed you can be, the longer you can stay down.
Thirdly is something we call the mammalian dive reflex or MDR. This is particularly evident in swimming mammals like whales or dolphins when they descend, sometimes in the case of the sperm whale to extremely deep depths and stay there for quite long periods. Not just minutes but 10's of minutes. Their MDR kicks in which slows the heart beat even more and causes a few more physiological reflexes all of which aid it's ability to be more efficient without oxygen. All mammals actually have this reflex although it is more developed with whales in particular. We have it too and immersion in water of the face helps switch it on. If it's cold water then the effect is even more pronounced with some of the nerves in our facial area.
That's just some of the reasons. You'll find some discussions about this online, particularly on freediving channels if it interests you. If you are interested in learning more then I recommend doing a freediving course through organisations such as SSI, AIDA or Apnea Australia (if you live in our part of the world). Thanks for the compelling question:).