title: Exploring Mediators of Physical Activity in Young Adult Cancer Survivors: Evidence from a Randomized Trial of a Facebook-Based Physical Activity Intervention.
abstract: OBJECTIVE
  This study examined the effects of a physical activity (PA) intervention for young adult cancer survivors on changes in self-efficacy, social support, and self-monitoring and determined whether changes in these social cognitive theory constructs mediated the relationship between the intervention and changes in PA.
  
  
  METHODS
  A 12-week randomized trial compared a Facebook-based intervention (FITNET) aimed at increasing moderate-to-vigorous intensity PA to a Facebook-based self-help comparison group. Young adult cancer survivors (N=86, aged 21-39) were randomly assigned to one of the two groups. Self-report measures of PA and psychosocial variables were collected at baseline and after 12 weeks.
  
  
  RESULTS
  The FITNET group reported lower self-efficacy for sticking to exercise (mean change=-0.38; 95% CI: -0.62 to -0.12; p=0.025) and social support from friends on social networking websites (mean change=-0.47; 95% CI: -1.45 to 0.65; p=0.039) relative to the self-help comparison group over time. Changes in social support from friends on social networking websites partially mediated the intervention effects on moderate-to-vigorous PA (mean indirect effect=-22.4; 95% CI: -62.0 to -2.8) in the unexpected direction. Across both groups, social support from friends and self-monitoring were positively associated with changes in moderate-to-vigorous PA.
  
  
  CONCLUSIONS
  The proposed mediators did not explain the positive effects of the FITNET intervention on mild PA. The lack of significant improvements in psychosocial constructs among FITNET participants may partly explain why the intervention did not increase moderate-to-vigorous PA relative to the self-help comparison group. Future PA interventions with young adult cancer survivors should examine targeting social support from friends and self-monitoring.
authors: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina.
authors: Carmina G
authors: CG
authors: Valle
authors: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina. ; Department of Health Behavior, Department of Nutrition, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina.
authors: Deborah F
authors: DF
authors: Tate
authors: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina. ; School of Nursing, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina.
authors: Deborah K
authors: DK
authors: Mayer
authors: Division of Health Promotion and Behavioral Sciences, University of Texas School of Public Health , Dallas, Texas.
authors: Marlyn
authors: M
authors: Allicock
authors: Department of Biostatistics, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina.
authors: Jianwen
authors: J
authors: Cai
mesh_terms: D000293:Adolescent; D000328:Adult; D019058:Community Networks / Q000706:statistics & numerical data*; D015444:Exercise / Q000523:psychology*; D005260:Female; D015438:Health Behavior; D006293:Health Promotion; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000534:rehabilitation*; D020377:Self Efficacy; D057566:Self Report; D060756:Social Networking; D011795:Surveys and Questionnaires; D017741:Survivors / Q000523:psychology*; D055815:Young Adult
keywords: Facebook; behavioral intervention; mediation; physical activity; psychosocial determinants; social networking website