The physiological benefits of vigorous exercise are well established. The existence of psychological benefits is less clear, however, due to methodological limitations common to investigatory studies. Two of these limitations are the difficulty of establishing appropriate control groups and the large variety of highly specific measures of psychological function available for consideration of effects. To address these limitations, we identified 63 pairs of monozygotic twins from the National Survey of Midlife Development in the United States who were discordant for the amount of vigorous exercise in which they engaged regularly. The twins who regularly engaged in vigorous exercise experienced greater positive psychological functioning than their nonexercising co-twins as measured by the latent factor representing the variance common to 8 measures of mood, optimism, control over life, and interpersonal aspects of personality. The magnitude of the difference was in excess of .4 standard deviations.
Bibliographical noteFunding Information:
This research was supported by the John D. and Catherine T. MacArthur Foundation Research Network on Successful Midlife Development, and by National Institute on Aging Grant #AG20166. Address correspondence to Wendy Johnson at firstname.lastname@example.org or Robert Krueger at email@example.com, Department of Psychology, 75 East River Road, Minneapolis, MN 55455.