title: Assessing the Effects of Interpersonal and Intrapersonal Behavior Change Strategies on Physical Activity in Older Adults: a Factorial Experiment.
abstract: BACKGROUND
  Little is known about which behavior change strategies motivate older adults to increase their physical activity.
  
  
  OBJECTIVE
  The purpose of this study was to assess the relative effects of two sets of behavior change strategies to motivate increased physical activity among older adults: interpersonal and intrapersonal.
  
  
  METHODS
  Community-dwelling older adults (N = 102, mean age = 79) were randomized in a 2 × 2 factorial experiment to receive interpersonal (e.g., social support, friendly social comparison; no, yes) and /or intrapersonal (e.g., goal setting, barriers management; no, yes) behavior change strategies, combined with an evidence-based, physical activity protocol (Otago exercise program) and a physical activity monitor (Fitbit One™).
  
  
  RESULTS
  Based on monitor data, participants who received interpersonal strategies, compared to those who did not, increased their average minutes of total physical activity (light, moderate, vigorous) per week, immediately (p = .006) and 6 months (p = .048) post-intervention. Similar, increases were observed on measures of functional strength and balance, immediately (p = .012) and 6 months (p = .003) post-intervention. The intrapersonal strategies did not elicit a significant increase in physical activity or functional strength and balance.
  
  
  CONCLUSIONS
  Findings suggest a set of interpersonally oriented behavior change strategies combined with an evidence-based physical activity protocol can elicit modest, but statistically and clinically significant, increases in older adults' physical activity and functional strength and balance. Future research should replicate these findings and investigate the sustained quantity of physical activity elicited by these strategies and their impact on older adults' quality of life and falls. Trial Registration The ClinicalTrials.gov registration identifier is NCT02433249.
authors.affiliation: School of Nursing, University of Minnesota, 5-140 Weaver-Densford Hall, 308 Harvard Street SE, Minneapolis, MN, 55455, USA. skmcmaho@umn.edu.
authors.forename: Siobhan K
authors.initials: SK
authors.lastname: McMahon
authors.affiliation: School of Kinesiology, Behavioral Aspects of Physical Activity, University of Minnesota, 209 Cooke Hall, 1900 University Avenue SE, Minneapolis, 55455, USA.
authors.forename: Beth
authors.initials: B
authors.lastname: Lewis
authors.affiliation: Division of Epidemiology and Community Health, University of Minnesota, School of Public Health, 1300 South Second Street Suite 300, Minneapolis, MN, 55454, USA.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Oakes
authors.affiliation: School of Nursing, University of Minnesota, 5-140 Weaver-Densford Hall, 308 Harvard Street SE, Minneapolis, MN, 55455, USA.
authors.forename: Jean F
authors.initials: JF
authors.lastname: Wyman
authors.affiliation: Division of Biostatistics, University of Minnesota, School of Public Health, A443 Mayo Building, Minneapolis, MN, 55455, USA.
authors.forename: Weihua
authors.initials: W
authors.lastname: Guan
authors.affiliation: Department of Psychology, University of Minnesota, N321 Elliot Hall, 75 E River Rd, Minneapolis, MN, 55455, USA.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Rothman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001521:Behavior Therapy; D015444:Exercise / Q000523:psychology*; D005260:Female; D000072936:Fitness Trackers; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D009042:Motivation / Q000502:physiology*; D011788:Quality of Life; D012944:Social Support
keywords: Accidental falls; Aged; Behavioral intervention; Factorial design; Motivation; Multiphase optimization strategy; Physical activity