title: Exploring the efficacy and moderators of two computer-tailored physical activity interventions for older adults: a randomized controlled trial.
abstract: BACKGROUND
  Important health benefits can be derived when low-cost (e.g., computer-tailored) physical activity interventions for older adults demonstrate sustained effects.
  
  
  OBJECTIVE
  The purpose of the study was to conduct in-depth analysis on the long-term efficacy of two tailored physical activity interventions for older adults.
  
  
  METHODS
  A randomized controlled trial (n = 1,971) with two computer-tailored interventions and a no-intervention control group was conducted. The two tailored interventions consisted of three tailored letters, delivered during 4 months. The basic tailored intervention targeted psychosocial determinants alone, while the environmentally tailored intervention additionally targeted environmental determinants, by providing tailored environmental information. Self-reported behaviors (i.e., total physical activity, transport walking and cycling, leisure walking and cycling, and sports) were measured at baseline and 12 months. Additionally, potential personal, health-related, and psychosocial moderators of the intervention effects were examined.
  
  
  RESULTS
  The environmentally tailored intervention was effective in changing total physical activity, leisure cycling, and sports compared with the basic intervention and control group. No intervention effects were found for the basic intervention. Moderation analysis revealed that participants with a higher age, lower body mass index, and higher intention were unresponsive to the interventions.
  
  
  CONCLUSIONS
  Providing environmental information is an effective intervention strategy for increasing physical activity behaviors among older adults, especially among certain "at-risk" subgroups such as lower educated, overweight, or insufficiently active participants. Moderation analysis was perceived as a promising method for identifying meaningful subgroups that are unaffected by an intervention, which should receive special attention in future interventions.
authors.affiliation: Department of Psychology, Open University of the Netherlands, Heerlen, The Netherlands. mm.vanstralen@vumc.nl
authors.forename: Maartje M
authors.initials: MM
authors.lastname: van Stralen
authors.forename: Hein
authors.initials: H
authors.lastname: de Vries
authors.forename: Catherine
authors.initials: C
authors.lastname: Bolman
authors.forename: Aart N
authors.initials: AN
authors.lastname: Mudde
authors.forename: Lilian
authors.initials: L
authors.lastname: Lechner
mesh_terms: D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D015444:Exercise / Q000523:psychology; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006293:Health Promotion / Q000379:methods*; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D020377:Self Efficacy; D012737:Sex Factors; D012944:Social Support; D013813:Therapy, Computer-Assisted / Q000379:methods*