Holding your breath may not be the flashiest feat of athleticism, but performing it at its highest level is still incredibly impressive, especially since it's something we've all done, and can all relate to. The limits to which some can push breath control, in fact, are more impressive than most people probably know.
Over the weekend, a 32-year-old free diver named Nicholas Mevoli died when testing those limits, attempting a record-setting free dive of 236 feet. He dove for three minutes and 38 seconds, and returned to the surface under his own power. He lost consciousness shortly thereafter, and was soon pronounced dead. It was a tragic end to an incredible human achievement: While three and a half minutes might seem like an eternity to hold your breath while swimming, what Mevoli did was actually far more notable than that. As a diver descends, water pressure forces human lungs to contract rapidly, reducing the amount of air they can hold. It's impossible to say how those three and a half minutes translate above water, but in context, they are astonishing.
The current record for pure breath-holding is 22 minutes, set by Stig Severinson in May of last year. And you probably remember David Blaine sitting in a bubble for 17 minutes 4 seconds. That is far longer than the 30 or 40 seconds most of us can hold for, to a really phenomenal degree. In a lot of ways, that gap between the average person and the elite is even more impressive than the exponential rate of increase in the world record—it was just over three minutes a century ago—as compared to marginal gains in something like the 100 meters. You run 100m far slower than Usain Bolt, in other words, but not 40 times slower, which is how most of us would stack up to Severinson. The mere fact that Blaine, a magician, would choose the feat as a "trick" nudges up against the disconnect: the maximum human capacity for holding your breath is long enough that it seems like magic. So how does that happen?
For divers, nature helps; all mammals have what's called mammalian diving reflex, which allows them to survive without air for longer periods of time while underwater. (This is why you'll occasionally hear a story about someone surviving for astonishing amounts of time after having fallen into an icy pond.) Training can help, too. One of the problems with holding your breath, it turns out, isn't exactly the lack of oxygen as much as it is the buildup of carbon dioxide; your blood acidifies when carbon builds up from lack of breathing. Training can slow the rate of this acidification, and also lead blood vessels to direct blood away from areas like the hands and feet and reroute it to the brain, and other crucial organs.
Just what does that training look like? General fitness helps, obviously. The basic method is what you'd think it is: hold your breath for as long as you can, exhale slowly, and repeat. (More than a few reps of this in a single session can be harmful.) The other main concern is learning how to relax. Keeping your muscles and especially your mind from firing helps conserve oxygen and keep your heart rate deflated. Still, you should expect to pass out during training, and in general it's dangerous to try this alone.
Regular training and relaxation don't get you into world record territory, though. Before record-setting attempts, divers and breath holders are allowed to hyperventalliate on pure oxygen, and will take as much into their lungs as possible. Obviously, it helps to have massive lungs to make the most of this. For that, there is something called lung packing. This consists of inhaling the very largest breath possible, and then, without exhaling, puffing your cheeks full of more air and attempting to force that air down into your lungs. You are literally stretching out your lungs so that they can hold more air. The average human female has a capacity of four liters, and the average male six liters. Endurance training can increase those numbers, but only slightly. Lung packing, however, can add up to three liters to a person's lungs. One diver named Herbert Nitsch even has a reported 14-liter capacity.
Would having bigger lungs be an advantage for other athletes, like a basketball or football player? It's actually hard to say. VO2 is the measurement of how quickly the body can process and use oxygen, and is separate from lung capacity. The two are (generally) linked, in a way that would make it difficult for a person's VO2 capacity to surpass lung capacity; however, grow the lungs, and who knows. At the very least, it might prove advantageous for someone to try expanding their lungs if they will be playing in notoriously high altitude places, like Denver or Mexico City. This is because a person's lungs are sized to process enough oxygen to power the muscles, but at high altitude, more air is required to transport the same amount of oxygen. Increased lung capacity would help limit the effects of altitude.
Still, that might not be the best idea. The thing is, lung packing isn't exactly the safest thing in the world. For one, there is a body of research suggesting that lung explosion (rupture) is a legitimate risk. For another, uhm, it might deform you. Cyclist Miguel Indurain has massive lungs for a non-diver (8 liters), and they were reportedly large enough to displace his stomach, which gave him a "trademark" paunch.
Chances are you won't need to hold your breath for 20 minutes in your lifetime, or even 5 minutes. But the capacity to improve how long you can hold it now into something that seems, on the surface, totally unrealistic remains fascinating.