The mechanism prevents people from holding their breath until they suffocate

Basically, humans cannot hold their breath until they suffocate, or even faint. So how does the body do this?

There are several areas of the brain that work to help people breathe. “First is the motor cortex,” said Anthony Bain, associate professor in the Department of Kinesiology at the University of Windsor, Canada. When it senses that a person is not breathing, it transmits signals to the respiratory center – the root part of the brain – spinal cord. This part controls muscles that allow people to breathe such as the diaphragm, the main muscle that helps inflate and deflate the lungs, and the intercostal muscles, which lie between the ribs and help expand the chest with each breath.

The second area is a network located toward the brain stem, the pre-Bötzinger complex, which acts as the body’s respiratory pacemaker. Even when a person is not breathing, this respiratory pacemaker is still running, trying to help the person breathe.

In addition, the body has chemical receptors that monitor oxygen and CO2 levels. They consist of two groups: central chemoreceptors and peripheral chemoreceptors. The central group of chemical receptors, located in the brain, primarily respond only to CO2, Bain said. The peripheral chemical reflex group is located in the neck, near the larynx. They react to CO2 and also low oxygen levels when a person prolongs their breath-holding period.

Finally, there are receptors in the lungs that detect stretch as the lungs inflate and deflate. When a person holds their breath and their lungs stop expanding, “alarm bells” begin to sound. When any of the above systems detects an abnormality, it sends a stress signal to the respiratory center in the brain, which will do everything it can to restart the breathing process.

Trained divers can hold their breath until they are about to faint. They are trained to bypass the signals sent by chemical receptors and cause oxygen levels to drop much lower than normal people. They only breathe when they feel they are about to lose consciousness. The record for holding your breath underwater without using oxygen during preparation is nearly 12 minutes.

One way for both trained and untrained people to increase their breath-holding time is to introduce more oxygen into the body, either by hyperventilating or inhaling pure oxygen. In fact, this is sometimes used in certain medical imaging procedures, when the patient needs to lie still for long periods of time. “You can give them 100% oxygen, and then, in some cases, they can hold their breath for up to five minutes,” Bain said.

This is also how the Guinness World Record for holding your breath was set. In 2021, Budimir Sobat, a Croatian free diver, held his breath for 24 minutes and 37 seconds.

The extra oxygen makes peripheral chemoreceptors think everything is fine. But even when they are disabled, the body still has backup mechanisms to make a person breathe before passing out. “This makes sense from an evolutionary perspective. Breathing is extremely important. Therefore, it makes sense that there is redundancy in the systems to force the body to continue breathing,” Bain explained. .