Nearly 200 studies have examined the impact that either acute or long-term exercise has upon cognition. Subsets of these studies have been reviewed using the traditional narrative method, and the common conclusion has been that the results are mixed. Therefore, a more comprehensive review is needed that includes all available studies and that provides a more objective and reproducible review process. Thus, a meta-analytic review was conducted that included all relevant studies with sufficient information for the calculation of effect size (N = 134). The overall effect size was 0.25, suggesting that exercise has a small positive effect on cognition. Examination of the moderator variables indicated that characteristics related to the exercise paradigm, the participants, the cognitive tests, and the quality of the study influence effect size. However, the most important finding was that as experimental rigor decreased, effect size increased. Therefore, more studies need to be conducted that emphasize experimental rigor.
Jennifer L. Etnier is now with the Health and Exercise Science Department at Wake Forest University, P.O. Box 7868, Reynolda Station, Winston-Salem, NC 27109. Walter Salazar is now with the School of Education at the University of Costa Rica, San Jose, Costa Rica. Daniel M. Landers and Priscilla Nowell are with the Department of Exercise Science and Physical Education at Arizona State University, Pebe 112, Tempe, AZ 85287. Steven J. Petruzzello is now with the Department of Kinesiology at the University of Illinois, Louise Freer Hall, Urbana, IL 61801. Myungwoo Han is now with the Department of Sport Psychology at the Korean Science Institute, Seoul, Republic of Korea.