The 12-month effects of exercise training on psychological outcomes in adults ages 50-65 years were evaluated. Ss (N = 357) were randomly assigned to assessment-only control or to higher intensity group, higher intensity home, or lower intensity home exercise training. Exercisers showed reductions in perceived stress and anxiety in relation to controls (p < .04). Reductions in stress were particularly notable in smokers. Regardless of program assignment, greater exercise participation was significantly related to less anxiety and fewer depressive symptoms, independent of changes in fitness or body weight (p < .05). It was concluded that neither a group format nor vigorous activity was essential in attaining psychological benefits from exercise training in healthy adults.
King et al. (1993) studied this question.