1. From the Department of Kinesiology and Applied Physiology, University of Colorado at Boulder (P.P.J., L.F.S., G.A.K., D.R.S.); the Department of Medicine, University of Colorado Health Sciences Center, Denver (L.F.S., R.A.Q., D.R.S.); the Clinical Research Center, Franz Volhard Clinic at the Max Delbrück Center, Medical Faculty of the Charité, Humboldt University, Berlin, Germany (J.J.); and the Autonomic Dysfunction Center, Vanderbilt University, Nashville, Tenn (J.R.S.).