You may have noticed that when you dive, you can hold your breath for much longer than when you simply try to hold your breath in the open air. If you have ever had this sensation, you can be sure that you are not imagining it. This phenomenon does exist, and not only in humans, but also in other mammals. At first glance, it seems illogical, given that in water, the chest experiences much higher pressure. But in fact, the reason is not the pressure, but the fact that our body begins to work differently in water and saves oxygen.
People can hold their breath longer underwater than in the open air. Photo source: ferra.ru
What changes in the body when we dive into water
The effect in question is called the mammalian diving reflex, or response. When mammals, including humans, dive into water, various physiological changes occur in their bodies. Why does this happen? There is no definitive answer to this question. Presumably, the signal for the body to “switch modes” is sensory information that is transmitted to the brain from the trigeminal nerve. Simply put, the body begins to work differently when the face becomes wet.
As soon as the brain receives the corresponding signal, the person stops breathing, while the heart rate decreases, and peripheral vascular resistance increases. Because of this, eddies are formed that slow down the blood flow. Due to the decrease in heart rate, the load on the heart decreases, as a result of which the organ begins to need oxygen to a lesser extent.
When a person dives into water, the heartbeat slows down, the blood flow slows down, and other changes in the body occur. Photo source: people.onliner.by
In addition, the body tries to preserve oxygen reserves for the most important organs, such as the brain and heart. To do this, blood is diverted from inactive muscle groups. It is not difficult to guess why the body takes all these measures – the goal is to preserve life. That is, some adaptation to new environmental conditions occurs in the water. By the way, thanks to them, even a person who cannot swim can save his life if he acts correctly in the water.
What happens to the body when a person does not breathe
When a person holds their breath, the level of carbon dioxide in the blood begins to rise, and at the same time the level of oxygen decreases. Due to the increase in carbon dioxide, a strong desire to inhale arises. Usually, it appears after 30 seconds.
Once the carbon dioxide in the blood reaches a certain threshold, the chemoreceptors begin to react to these changes and send an “alarm signal” to the brain. As a result, at this point the urge to breathe becomes even stronger and increases. At some point, the desire to breathe becomes so strong that a person is unable to control it. As a result, the diaphragm, that is, the respiratory muscle, involuntarily contracts and the person begins to breathe. Therefore, as we have already said, it is impossible to suffocate simply by holding your breath.
Usually, an untrained person cannot hold their breath for longer than 60-80 seconds. Photo source: sitewebok.ru
How long can a person hold their breath underwater
When an untrained person holds their breath, after a while they involuntarily stop and take a breath. This usually happens after only 60-80 seconds or even earlier. A trained person, that is, after certain exercises, can hold their breath for a much longer time.
The current record is 24 minutes 37 seconds, set by freediver Budimir Shobat in 2021. Let us remind you that freediving is underwater swimming without oxygen tanks, that is, holding your breath.
But even an experienced freediver needs special training to hold his breath for such a long time, namely hyperventilation of the lungs with pure oxygen. That is, a person breathes oxygen before diving underwater. This helps prevent or at least delay the involuntary breathing reflex. Thus, hyperventilation of the lungs allows people not to breathe underwater for up to 20 minutes or even longer, as Budimir Shobat did. By the way, actress Kate Winslet did not breathe underwater for more than 7 minutes after hyperventilation during the filming of Avatar: The Way of Water.
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Surely you immediately had another question – how long can an untrained person not breathe underwater without preliminary hyperventilation of the lungs? The result is much lower, but also impressive – the current record is 11 minutes 35 seconds. What should you do to learn to hold your breath for a long time?
In fact, this does not require anything complicated – you just need to train daily, that is, not breathe. According to some scientists, daily breath holding on inhalation not only has a training effect, but is also an excellent means of relaxation.