title: Physical activity mediates the relationship between program participation and improved mental health in older adults.
abstract: OBJECTIVE
  There is an implicit assumption that increased physical activity (PA) levels are responsible for the mental health benefits resulting from participation in PA programs. Other factors associated with participation may in fact be responsible. The purpose of this study was to examine whether changes in PA mediated the effects of two PA programs (Active Choices [AC] and Active Living Every Day [ALED]) on mental health outcomes.
  
  
  METHODS
  Secondary data analyses of quasi-experimental study.
  
  
  METHODS
  A sub-sample of older adults who participated in AC (n = 744) and ALED (n = 853) were included in the current analyses. MacKinnon's product of coefficients was used to test change in PA as a mediator of the relationship between program dose and change in mental health outcomes (depressive symptoms, stress, and number of days with poor mental health).
  
  
  RESULTS
  Change in PA explained 19% (AC) and 13% (ALED) of the absolute effects of program dose on depressive symptoms, 18% (AC) and 14% (ALED) of the effects on stress, and 37% (ALED) of the effects on days with poor mental health.
  
  
  CONCLUSIONS
  Mounting evidence from both epidemiological studies and controlled trials suggests that PA can improve mental health. This study adds that increasing PA levels may improve mental health in older adults in 'real-world' settings.
authors: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, 921 Assembly Street, Columbia, SC 29208, USA. Electronic address: Katie_Becofsky@Brown.edu.
authors: K
authors: K
authors: Becofsky
authors: Department of Health Sciences, Saginaw Valley State University, 7400 Bay Road, University Center, MI 48710, USA.
authors: M
authors: M
authors: Baruth
authors: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, 921 Assembly Street, Columbia, SC 29208, USA; Prevention Research Center, University of South Carolina, 921 Assembly Street, Columbia, SC 29208, USA.
authors: S
authors: S
authors: Wilcox
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000517:prevention & control*; D009043:Motor Activity; D015397:Program Evaluation; D058992:Social Participation
keywords: Depressive symptoms; Exercise; Mediation; Older adults; Stress; Translational research