Guidance from Stephen Seiler.Every day.

Stephen Seiler, PhD, is an American-born exercise physiologist and Professor of Sport Science at the University of Agder in Kristiansand, Norway, where he has worked since 1997 and previously served as Dean of the Faculty of Health and Sport Sciences and Vice-Rector for Research and Innovation. He earned a master's in exercise science at the University of Arkansas (1987) and a PhD in kinesiology — exercise physiology and biochemistry — at the University of Texas at Austin (1995). Over more than two decades studying cyclists, rowers, cross-country skiers, orienteers, and distance runners, he became internationally recognized for quantifying training-intensity distribution in elite endurance athletes — work that catalyzed research on the "polarized" model, in which roughly 80% of training is done at low intensity and 20% at high intensity. He is a Fellow of the American College of Sports Medicine, a founding editorial board member of the International Journal of Sports Physiology and Performance, a former executive board member of the European College of Sport Science, and a research consultant to the Norwegian Olympic Federation. He has authored more than 100 peer-reviewed papers alongside as many popular-science articles.