David Blaine set a world record on April 30 by holding his breath under water for 17 minutes, 4 seconds.

JOHN TIERNEY ESSAY

GRAND CAYMAN ISLAND - A breath-holding experiment, conducted recently at a swimming pool on Grand Cayman Island, was being run by Ralph Potkin, a pulmonologist in Los Angeles who is a researcher trying to understand the human propensity for going without air.
This ability is not new - it involves an ancient reflex shared with dolphins and other mammals - but it has only recently been rediscovered, thanks largely to the sport of free diving. Using just their lungs, free divers have kept going deeper and holding their breath longer than anyone expected.
“The empiric results have consistently exceeded theoretical predictions,” Dr. Potkin said. He is the team physician for the United States free-diving team, whose members were training at Grand Cayman Island along with David Blaine, the famous magician, who was training to break the world record for breath-holding.
A century ago, Houdini was celebrated for being able to hold his breath for three and a half minutes. Today even a novice can quickly learn to last longer than that, as I discovered under the tutelage of Kirk Krack, the free-diving coach who has been training Mr. Blaine for his worldrecord attempt.
Researchers in the 1960s calculated, based on lung capacity and the effect of water pressure, that humans could not dive deeper than 50 meters. Today free divers are going down more than 180 meters and returning in apparently fine shape. Most of the time.
Dr. Potkin said one of the most common and sometimes fatal dangers of free diving is a blackout - and one of the reasons you should not try any prolonged breath-holding unless someone like Mr. Krack is supervising.
“Divers rarely get into trouble at depth,” Dr. Potkin said. “But as the diver approaches the surface, the decreasing water pressure causes a drop in pressure of the oxygen in the brain. If the level in the brain gets too low, it’s like a switch: lights out.”
The natural impulse to stop holding your breath (typically within 30 seconds or a minute) is not because of an oxygen shortage but because of the painful buildup of carbon dioxide.
Mr. Blaine has been concentrating on lowering his oxygen consumption by slowing his metabolism, partly through diet and partly through relaxation. In a test by Dr. Potkin, Mr. Blaine on command quickly lowered his heart rate by 25 percent.
“David seems to have a phenomenal ability, like Buddhist monks, to control his body,” Dr. Potkin said.
When Mr. Blaine began his breath-hold in the pool, his heart rate during the first minute fell to 46 from 81, a drop that was not entirely his own doing. Immersing the face in water produces a protective action in humans similar to that in dolphins, seals, otters and whales. Called the mammalian diving reflex, it quickly lowers the heart rate and then constricts blood vessels in the limbs so that blood is reserved for the heart and the brain.
By exploiting that reflex, free divers can remain active underwater for more than four minutes, and much longer if they remain still. The world-record holders have exceeded nine minutes after filling their lungs with ordinary air, and more than 16 minutes after inhaling pure oxygen.
As part of his training, Mr. Blaine was hooked up to electrodes and monitored by Dr. Potkin. Mr. Krack was in the pool with him watching for danger signs, like blue lips. Mr. Blaine remained motionless until he heard he had hit 16 minutes.
He emerged and broke the surface at 16:09 - stopping, as he’d planned, just shy (by five seconds) of the Guinness World Record for pure-oxygen apnea.
“It felt pretty good,” Mr. Blaine said . “I wasn’t even there most of the time. I imagined being deep in the ocean.”
Any pain during the 16 minutes?
“Not even a little bit,” he replied.
On April 30, Mr. Blaine officially broke the world record when he held his breath for 17 minutes and 4 seconds in front of Guinness judges.
No one is sure of the long-term neurologic effects of such prolonged apnea, Dr. Potkin said, but his examination of Mr. Blaine (including the subsequent results from blood tests) did not turn up any problems or abnormalities.
“Many doctors still don’t realize the body can tolerate prolonged apnea so well,” Dr. Potkin said. “My hope is to understand the process so we can apply the lessons to help people with heart and lung disease and neurological problems.”