W. Larry Kenney, Ph.D., FACSM, is a professor of physiology and kinesiology and the Marie Underhill Noll Chair in Human Performance at The Pennsylvania State University. He received his bachelor's and master's degrees in biology from the Indiana University of Pennsylvania, and his doctorate in physiology from Penn State. Kenney has done extensive research in the area of aging and temperature regulation, including responses of older men and women to heat and cold stress and dehydration. He has published over 250 scientific articles and book chapters and has lectured around the world on these topics. Kenney has been active in the American Physiological Society and the American College of Sports Medicine (ACSM), serving as president of ACSM in 2003-04. He has also served as chair of the Gatorade Sports Science Institute and senior editor of the 5th edition of ACSM's Guidelines for Exercise Testing and Prescription and is the primary author of the best-selling textbook, Physiology of Sport and Exercise.