When Lauren Earthman signed up for a research project studying the effects of altitude on the human body, she thought she knew what to expect. It would be tough, but Earthman—a freshman at the University of Oregon in Eugene—was a competitive 1500-meter runner, after all. Then, she climbed out of the oxygen-equipped bus that had carried her to an elevation of 5260 meters in the Bolivian Andes. She felt OK—until she had to walk up a set of stairs. Suddenly, even that simple action, she says, was “immensely more difficult” than what she was expecting… more
