title: Psychosocial mediators of two community-based physical activity programs.
abstract: BACKGROUND
  Previous findings are inconclusive regarding the mediators of physical activity behavior change.
  
  
  OBJECTIVE
  To test self-efficacy and social support as mediators of Active Choices, a telephone-delivered physical activity intervention, and Active Living Every Day, a group-based physical activity intervention, implemented with midlife and older adults in community settings.
  
  
  METHODS
  MacKinnon's product of coefficients was used to examine social support and self-efficacy as mediators of change in physical activity. The proportion of the total effect mediated was calculated. Each model controlled for age, gender, race (white vs. non-white), body mass index (BMI), and education (high school graduate or less vs. at least some college).
  
  
  RESULTS
  Increases in self-efficacy mediated increases in physical activity among Active Choices (n = 709) and Active Living Every Day (n = 849) participants. For Active Living Every Day, increases in social support also mediated increases in physical activity in single mediator models.
  
  
  CONCLUSIONS
  Increasing self-efficacy and social support may help increase physical activity levels in older adults.
authors.affiliation: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, 921 Assembly Street, Columbia, SC, 29208, USA, becofsky@email.sc.edu.
authors.forename: Katie
authors.initials: K
authors.lastname: Becofsky
authors.forename: Meghan
authors.initials: M
authors.lastname: Baruth
authors.forename: Sara
authors.initials: S
authors.lastname: Wilcox
mesh_terms: D000368:Aged; D005260:Female; D015438:Health Behavior; D006293:Health Promotion; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009043:Motor Activity; D015397:Program Evaluation; D012111:Residence Characteristics; D020377:Self Efficacy; D012944:Social Support