On June 8, 2009, Stéphane Mifsud set a new "static apnea" world record: 11 minutes 35 seconds. The 37-year-old Frenchman beat the previous record by a full 1 minute and 23 seconds, setting a very high bar for future competitors. Static apnea is what most of us would call "holding our breath," the sort of thing you might have done at age 12 to prove you're cool. I was your classic last-to-be-picked kid when it came to team sports, but when it came to breathing, I could literally hold my own. My record stands at over three minutes — not quite in the same league as Mifsud.

The rules for competitive static apnea are pretty straightforward: You simply hold your breath underwater for as long as possible, no pre-competition oxygen allowed. This differs from the Guinness World Record rules, which allow the use of oxygen in preparation, enabling competitors to essentially double their period of breathlessness.

On average, we take about 12 breaths per minute. Exertion causes the body to automatically speed up that rate, while deep relaxation or meditation slows it down. If we consciously hold our breath, something happens at about the one-minute mark that causes us to take another breath. That "something" is still debated among researchers. Until recently, the usual reason given was that our urge to breathe is triggered by the increase of carbon dioxide in our blood. As we metabolize oxygen, we produce carbon dioxide. At a certain CO2 to O2 ratio, the brain's survival mechanism kicks in and we breathe, whether we want to or not. The odd thing about this explanation is that our lungs typically hold sufficient oxygen for about four minutes, so why do we need to breathe much earlier than that?

More recently (as discussed in the April 2012 issue of Scientific American), it's been speculated that involuntary inhalation may have more to do with messages sent to the brain by the diaphragm, which is tightened when we breathe in. After it has been contracted for what the brain deems is too long, breathing just happens.

The debate over what causes our involuntary urge to breathe has implications for "free divers" who descend deep in the ocean without SCUBA apparatus. They typically hyperventilate immediately before diving, which lowers the level of carbon dioxide in the bloodstream. Together with our innate "mammalian diving reflex" — which automatically lowers our rate of heartbeat and constricts our capillaries when we're underwater — this allows them to dive deep and long. The world depth record for "constant weight apnea without fins" stands at more than 300 feet deep!

Hyperventilation can, however, be fatally dangerous, since it fools the body into thinking it does not need oxygen by artificially lowering CO2 bloodstream levels ("hypocapnia") without increasing the amount of oxygen in the body. This low-oxygen condition of cerebral hypoxia can cause a person to pass out. If that happens underwater, the victim drowns quietly without any warning signs. Free divers aren't the only ones at risk in water. Hyperventilation prior to breath-hold pool laps can lead, rather easily, to this dangerous condition.

Nature gave us our breath reflex for a reason, and bodies can only tolerate being overridden by minds to a limited extent. Whether you're a free diver, a lap swimmer or a kid trying to prove your courage: Never hyperventilate!

Barry Evans (barryevans9@yahoo.com) believes our current land-based existence is a brief two-dimensional hiatus between emerging from the oceans 400 million years ago and adapting to living in space.