Humans can survive without food for three weeks, without water for three days, but without oxygen for barely three minutes. Responding to conditions at high altitude, respiration and heart rate escalate immediately, straining to deliver oxygen. The kidneys, sensitive monitors of our blood chemistry, react by secreting a hormone called erythropoietin (EPO), which stimulates the production of extra red blood cells in the bone marrow. These are the tractor-trailers that haul oxygen to the power plants (cell mitochondria). Put a lot more tractor-trailers on the highway and you'll be able to burn a lot more fuel, substantially boosting endurance and power. (More red blood cells is exactly what blood-doping and synthetic EPO injections create, hence the suppurating controversy in some sports, particularly road cycling.) Although going from sea level to the top of a fourteener will temporarily stimulate the kidneys to increase EPO production threefold, the importance of this increase to mountain climbing pales in comparison to increasing your blood oxygen level simply by breathing harder and faster—otherwise known as ventilatory acclimatization.
"A decade and a half ago, after studying the current literature, it occurred to us that there might be a way to get the best of both worlds," says Levine. "That is, have athletes live at moderate altitude, taking advantage of the improved oxygen transport system, but train at low altitude, where the extra oxygen would allow for maximal workouts."
With colleague James Stray-Gundersen, and funded by the U.S. Olympic Committee, Levine set out in 1989 to test his hypothesis. For seven years the team conducted multiple experiments with elite American endurance athletes—some living and training at moderately high altitude (Deer Valley, Utah, 7,200 feet), some living and training at sea level (San Diego), and some living at moderately high altitude (Deer Valley) but training at moderate altitude (Salt Lake City, 4,390 feet). In 1997 Levine and Stray-Gundersen published their findings in the Journal of Applied Physiology in an influential paper titled "Living High—Training Low."
"What we found then," says Levine, "and have confirmed in subsequent studies, is that athletes who live at moderately high altitude but train at low altitude can improve performance at sea level by 1 to 3 percent." In other words, living high and training low turns out to be a legal, natural, noninvasive form of blood doping. (Whether it is ethical or not is another, very complicated question.)
At about the same time, Heikki Rusko, a sports scientist from Finland, reported similar results, although his method of bringing endurance athletes up and down in altitude was dramatically different. Finland is as flat as the lakes that cover it, so Rusko built "nitrogen huts" to simulate high altitude. These huts reduced the availability of oxygen not by altering the atmospheric pressure, but by simply pumping in more nitrogen. Again, athletes increased their performance by 1 to 3 percent.
Which may not seem like much until you realize that in the 10,000 meters at the 1996 Olympics, the difference between the gold medal, won by Ethiopian Haile Gebrselassie in 27:07.34, and eighth place, taken by Rwandan Mathias Ntawulikura in 27:50.73, was less than 3 percent. The difference between Lance Armstrong's winning time in this year's Tour de France and that of the 100th-place finisher was also less than 3 percent.
"Put it this way," says Larry Kutt, owner of Colorado Altitude Training (CAT). "In the world of professional endurance athletics, 3 percent is the difference between being the best on earth, with all the fame and million-dollar contracts that that brings, and flipping burgers, trying to find time to train."
At least that's Kutt's claim. His company, capitalizing on Levine's research and Rusko's engineering, has begun to build something called a Colorado Mountain Room for professional athletes. As part of my preparation before heading off on an expedition to climb a notorious 20,000-foot peak, I spent about two weeks sleeping—or trying to—in a room jury-rigged with CAT equipment to simulate oxygen availability at varying altitudes. "No more driving up and down the mountain," promises Kutt. "We turn your bedroom into a nitrogen room—an oxygen-deprived environment in which you can sleep high–train low right in your own home."
I had contacted CAT, one of several U.S. companies now marketing oxygen-deprivation chambers for endurance athletes, at the suggestion of Peter Hackett, another of America's foremost altitude specialists. Hackett has published extensively on the pathophysiology of altitude-induced illnesses. He summited Everest on a medical research expedition in 1981, directed his own physiology research lab at 14,200 feet on Mount McKinley from 1981 to 1989, and is now president of the International Society for Mountain Medicine. I was interested in finding out whether such a device might be useful in preacclimatizing for a speed ascent of a high peak.
"It would be a worthwhile, if limited, experiment," Hackett said. "If you sleep in a nitrogen room every night for several weeks prior to departure, even if it doesn't make you climb any faster, it will definitely reduce your risk of AMS, HAPE [high-altitude pulmonary edema] and HACE [high-altitude cerebral edema]."