Bruce Johnson is a soft-spoken man who's drawn to extremes.
He once camped on the edge of a soaring cliff in Argentina, with 40-mile-per-hour winds threatening to blow his tent away. "Like sitting behind a jet plane," he says.
As a scientist at the Mayo Clinic, Johnson has gone to some of the most forbidding places on the planet (including the South Pole) to explore one question: "What are the extremes that the human body can endure?" Monday, he takes his quest to Mount Everest.
Johnson, 54, is leading a team of scientists to "the promised land," as one colleague calls it, to study the extraordinary ways the body can change on the highest mountain on Earth.
In Nepal, Johnson and his colleagues will trek on foot for 10 days, to an elevation of 17,500 feet, to set up a Mayo outpost at Everest's base camp.
"We're bringing 1,300 pounds of medical equipment on the backs of yaks," said Johnson. "We're essentially creating a remote laboratory up there."
As part of the research, Mayo scientists will get up close and personal -- very personal -- with the members of an expedition cosponsored by National Geographic, the North Face and Montana State University. The plan is to hook everyone, climbers and staff, up to tiny sensors that will track their heart rates beat by beat. They'll test their oxygen levels, blood and urine. Even their sleep will be measured; if they wake up after a nightmare, the scientists will know it.
With luck, Johnson will return with a mountain of data -- and some lessons that could benefit patients with heart disease and other chronic conditions.