- What determines how long someone can hold a breath? People usually need to gasp for air long before their brain or body runs out of oxygen (the obvious limitation).
- Investigating what limits our control over breath holding has been difficult, but decades of research suggest that the diaphragm, which contracts to inflate the lungs, plays a key role.
- The best hypothesis is that the diaphragm sends signals to the brain about how long it has been contracted and how it is biochemically reacting to depleted levels of oxygen or rising levels of carbon dioxide. Initially those signals cause mere discomfort, but eventually the brain finds them intolerable and forces breathing to start again.
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Take a deep breath and hold it. You are now engaging in a surprisingly mysterious activity. On average, we humans breathe automatically about 12 times per minute, and this respiratory cycle, along with the beating of our heart, is one of our two vital biological rhythms. The brain adjusts the cadence of breathing to our body’s needs without our conscious effort. Nevertheless, all of us also have the voluntary ability to deliberately hold our breath for short periods. This skill is advantageous when preventing water or dust from entering our lungs, when stabilizing our chests before muscular exertion and when extending how long we can speak without pause. We hold our breath so naturally and casually that it may come as a surprise to learn that fundamental understanding of this ability still eludes science.
(Feel free to exhale now, if you haven’t already.)
This article was originally published with the title The Limits of Breath Holding.