by The Fish

An incredible news story came out this winter about a Swiss freediver named Peter Colat who set the world record for holding his breath underwater at 19 minutes and 21 seconds! This length of time is astounding to any normal suburbanite, who generally starts to tremble after 30 seconds of “static apnea” as it is called.

Some understanding will bring this lofty feat a little closer to earth. Like any world-class competitor, men like Colat are very dedicated to their trade. Through good genes and intensive training, their bodies have become conditioned to adapt to extreme oxygen depravation. On top of this, they generally breathe pure oxygen for several minutes before taking the plunge, leaving their blood highly oxygenated. And if their bodies start to react poorly to the oxygen deprivation, they know the warning signs to look for – not to mention their team of experts and medical personnel on hand.

Achievements like this make great news stories, but could set the stage for tragedy if emulated.  “Who can hold their breath the longest?” is as common a pool-side competition as you’ll find. Usually a group of kids submerge only to shoot up less than a minute later gasping for air, the last of which to surface being the winner. But this seemingly harmless game sometimes leads to what is known as “shallow-water blackout,” where people lose consciousness underwater and often drown.

The blackout occurs because the body’s natural signal to take a breath comes from high carbon dioxide levels in the blood. In these cases, someone about to hold their breath underwater generally hyperventilates by taking several large breaths before going under. This artificially lowers the level of carbon dioxide in the blood. When the body starts to starve for oxygen, they don’t feel it because the body’s warning signal (high carbon dioxide levels) has been neutralized.

Shallow water blackout is deceptively dangerous for a few reasons. First, it’s not widely publicized or understood. Most people view pushing your lungs’ capacity the same as exercising a muscle. Second, before a person blacks out in these scenarios, they’re usually motionless anyway. So it’s hard for others to tell that there’s a problem. Third, oxygen depravation in these cases is rarely preceded by a strong feeling of discomfort. So there is nothing to warn you of danger.

The underwater world is a wonderfully fascinating place to test your limits. But it’s best to leave some limits to the experts.