fitness

AEROBIC FITNESS AND COGNITION: A META-ANALYTIC EXAMINATION OF THE CARDIOVASCULAR FITNESS HYPOTHESIS PRISCILLA M. NOWELL, DANIEL M. LANDERS, AND JENNIFER L. ETNIER ARIZONA STATE UNIVERSITY A meta-analysis was conducted to investigate the effect of aerobic fitness upon cognition. Published and unpublished studies from 1927 to 1995 were located through computer and hand searches. Studies were chosen if they examined the effect of aerobic exercise (independent variable) upon cognition (dependent variable), and included a maximal or submaximal measure of VO₂. Variables related to study information, design, subject, exercise, and dependent measure characteristics were coded. A search produced 31 studies with 1,193 subjects. A significant, but small, overall improvement by 0.21 of a standard deviation was found for the effect of aerobic fitness upon cognition. The mean within-subjects change in VO_2max from pretest to posttest was only about 13 percent. Exercise intensity, average duration of each bout, and average number of weeks of training were significant moderator variables. While aerobic exercise significantly improved cognition by an average of 0.18 of a standard deviation, a linear relationship was not found between factors associated with an increase in VO_2max and an improvement in cognition. Studies with more threats to internal validity, nonrandom subject assignment, nonequivalent comparison groups, poor or no supervision, and an uncontrolled exercise environment produced larger effect sizes than better designed studies. To determine whether the effect is real or the result of a behavioral artifact, future research should emphasize methodological rigor in study design, and include a mixed aerobic exercise paradigm (chronic aerobic exercise with an acute bout of aerobic exercise prior to the cognitive test) at an intensity and duration recommended by the American College of Sports Medicine (1990) guidelines.

An abstract of this presentation was published in the Congress Proceedings of the Fourth I.O.C. Congress on Sport Sciences: "Training and Care of Athletes--Current Concepts and Technologies," (Addendum), October, 1997, p. 22. Lausanne, Switzerland: International Olympic Committee Medical Commission.