title: GrOup based physical Activity for oLder adults (GOAL) randomized controlled trial: study protocol.
abstract: BACKGROUND
  Physical activity has health benefits across the lifespan, yet only 13 % of Canadian older adults are sufficiently active. Results from a number of observational studies indicate that adults display positive preferences for exercising with others of a similar age and same gender, and that intra-group age- and gender-similarity are associated with elevated exercise adherence. However, research has yet to experimentally examine the extent to which intra-group age- and gender-related similarity affect exercise adherence behaviors.
  
  
  METHODS
  The GrOup-based physical Activity for oLder adults (GOAL) trial is a three-arm randomized control trial that will examine the efficacy of two different group-based exercise programs for older adults (informed by the tenets of self-categorization theory) in relation to a standard group-based exercise program. Within this manuscript we outline the design and proposed evaluation of the GOAL trial. The first arm is comprised of exercise groups made up of participants of a similar-age and of the same gender; the second arm consists of groups with similar-aged mixed gender participants; the control arm is comprised of mixed-aged mixed gender participants. We aim to compare the adherence rates of participants across conditions, as well as potential moderation effects and mediating mechanisms.
  
  
  CONCLUSIONS
  Results from this trial will inform intervention designs to improve the exercise adherence behaviors of older adult. At a systems-level, should support be derived for the efficacy of the interventions tested in this trial, changing group composition (i.e., age, gender) represents a feasible program adaptation for physical activity centers.
  
  
  BACKGROUND
  ClinicalTrials.gov # NCT02023632 . Registered December 13, 2013.
authors.affiliation: School of Kinesiology, University of British Columbia, Vancouver, BC, Canada. mark.beauchamp@ubc.ca.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Beauchamp
authors.affiliation: School of Kinesiology, University of British Columbia, Vancouver, BC, Canada. harden.samantha@vt.edu.|Department of Human Nutrition, Foods and Exercise, Virginia Tech, Blacksburg, VA, USA. harden.samantha@vt.edu.|Fralin Translational Obesity Research Center, Blacksburg, VA, USA. harden.samantha@vt.edu.
authors.forename: Samantha M
authors.initials: SM
authors.lastname: Harden
authors.affiliation: School of Kinesiology, University of British Columbia, Vancouver, BC, Canada. svenjaawolf@gmail.com.
authors.forename: Svenja A
authors.initials: SA
authors.lastname: Wolf
authors.affiliation: Behavioural Medicine Laboratory, School of Exercise Science, Health and Physical Education, University of Victoria, Victoria, BC, Canada. rhodes@uvic.ca.
authors.forename: Ryan E
authors.initials: RE
authors.lastname: Rhodes
authors.affiliation: School of Kinesiology, University of British Columbia, Vancouver, BC, Canada. Yan_Liu@hms.harvard.edu.|Department of Cell Biology, Harvard Medical School, Harvard University, Boston, MA, USA. Yan_Liu@hms.harvard.edu.
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Kinesiology, University of British Columbia, Vancouver, BC, Canada. william.dunlop@ucr.edu.|Department of Psychology, University of California-Riverside, Riverside, CA, USA. william.dunlop@ucr.edu.
authors.forename: William L
authors.initials: WL
authors.lastname: Dunlop
authors.affiliation: Department of Psychology, University of British Columbia, Vancouver, BC, Canada. tschmader@psych.ubc.ca.
authors.forename: Toni
authors.initials: T
authors.lastname: Schmader
authors.affiliation: School of Kinesiology, University of British Columbia, Vancouver, BC, Canada. bill.sheel@ubc.ca.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Sheel
authors.affiliation: Faculty of Education, University of British Columbia, Vancouver, BC, Canada. bruno.zumbo@ubc.ca.
authors.forename: Bruno D
authors.initials: BD
authors.lastname: Zumbo
authors.affiliation: Department of Human Nutrition, Foods and Exercise, Virginia Tech, Blacksburg, VA, USA. estabrkp@vt.edu.|Fralin Translational Obesity Research Center, Blacksburg, VA, USA. estabrkp@vt.edu.|Department of Family Medicine, Carilion Clinic, Roanoke, VA, USA. estabrkp@vt.edu.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Estabrooks
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D002170:Canada; D015444:Exercise; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D015438:Health Behavior; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D010809:Physical Fitness; D012107:Research Design