1. Department of Human Physiology, University of Oregon, Eugene, Oregon;
2. Oregon Heart and Vascular Institute, Echocardiography, Springfield, Oregon;
3. University of Lausanne, Department of Physiology and Institute of Sports Sciences, Lausanne, Switzerland;
4. Altitude Research Center, University of Colorado Anschutz Medical Campus, Denver, Colorado; and
5. Department of Biology, University of Colorado, Colorado Springs, Colorado