Extreme athlete offers medical lessons

At Brigham and Women's Hospital, a group of doctors last week gathered around the ''most physiologically gifted athlete in the world," and watched her breathe.

It was a multistep process, beginning with an exhale that forced nearly all of the oxygen out of her midsection. Her stomach reemerged and bulged slightly as she filled her lungs from the bottom up. She expanded her rib cage to allow in more air. And finally she gulped in short ''packing" breaths.

By the time world champion free diver Tanya Streeter was done, she had inhaled 50 percent more air than a normal person her size, and captivated several dozen doctors who were interested in learning lessons from her endurance.

This lung capacity is part of what allows Streeter to do something no one else in the world can do -- plunge 400 feet under water on one gulp of air and return under her own power. At the bottom of her dive, the pressure on her chest shrinks each of her lungs to the size of a potato.

By the time she has returned to the surface, she has held her breath for nearly four full minutes. Exactly how her body can stand it, nobody knows -- not even Streeter.

''My interest in the science and physiology really comes from the fact that I don't quite understand why I can do what I can do," said Streeter who was featured in Sports Illustrated Women in 2001 as the ''most physiologically gifted athlete in the world."

''In my sport, your body is your equipment, so if you understand your equipment better, you'll perform better."

To doctors, her abilities make her perfect for studying how the body responds to extreme stress.

Divers often temporarily experience irregular heartbeats, known as cardiac arrhythmias. Because blood rushes to their chests to equalize the pressure, their lungs sometimes start to fill with blood fluid -- a condition known as pulmonary edema. But they can bounce back from these syndromes, which in most people would be symptoms of a serious disease.

By studying divers, doctors can research these stress-induced health problems, as well as get insight into how the bodies of these athletes adapt and survive such extreme conditions.

''You can learn a lot about how the body normally functions, but also how it malfunctions in certain diseases," said Dr. Massimo Ferrigno, an anesthesiologist at Brigham and Women's who has enlisted Streeter to be studied both in actual ocean dives and in a water-pressure simulator known as a hyperbaric chamber. Beginning this summer, if they're able to secure funding, Ferrigno will hook Streeter up to monitors that measure her heart rate, blood pressure, chest volume and pressure, and the amount of air exhaled when she surfaces.

Last week, he brought her to the hospital to talk to his anesthesiology students and other clinicians, hoping to spread his excitement about the research.

''Tanya," he said, ''defies conventional wisdom."