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By Peter C.M. Molenaar, Richard M. Lerner, Karl M. Newell. Edited by Peter C. M. Molenaar. Karl M. Newell, PhD, is the Marie Underhill Noll Chair of Human Performance and Professor of Kinesiology and Biobehavioral Health at Penn State.
When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.