for National Geographic News
Most mountaineers who traipse above elevations of 23,000 feet (7,000 meters) or so opt for bottled oxygen. It helps them stay alert and focused on reaching the summit, not to mention more fundamental objectives, such as returning to base camp alive.
At high altitude, oxygen is less dense. As Robert Schoene, an expert on high-altitude pulmonary medicine at the University of California, San Diego, noted, "In order to obtain the amount of oxygen that you need for energy combustion or generation, you need to breathe a lot more."
Ed Viesturs, a Seattle, Washington-based climber, is a rare exception. He has summitted, without the aid of supplemental oxygen, 13 of the 14 highest mountains in the world. The peaks rise more than 8,000 meters (26,250 feet) above sea level.
Next year Viesturs aims to summit the last unclimbed mountain on his list, Annapurna. The mountain rises 8,091 meters (26,545 feet) in the Nepalese Himalaya.
If successful, Viesturs will close the book on Endeavor 8,000, his quest to become the second person in the world, and the first American, to climb the 14 highest peaks on Earth without the use of supplemental oxygen.
"It was a challenge to see if I could climb mountains for what they are," Viesturs said.
Schoene said Viesturs's unique blend of physical characteristics and mountain savvy allow him to take on such a challenge: Physically, Viesturs has aerobic abilities on par with the world's elite athletes. Mentally, he's among the most efficient mountaineers in the business.
Viesturs got serious about mountaineering in the late 1970s while a college student at the University of Washington in Seattle.
"As I was climbing early on, I would notice at the end of the day that I performed better than the other folks I was with," he said. "I felt better during the climb, and as I went higher and higher, it wasn't as big a deal to me as to other people."
In 1997 Schoene performed a series of physiological tests on Viesturs and found the mountaineer has a high VO2 max, a measure of the amount of oxygen the body can take in and use each minute. Only world-class endurance athletes such as cyclist Lance Armstrong have a higher VO2 max than Viesturs, Schoene said.
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