title: Mobile and Wearable Device Features that Matter in Promoting Physical Activity.
abstract: BACKGROUND
  As wearable sensors/devices become increasingly popular to promote physical activity (PA), research is needed to examine how and which components of these devices people use to increase their PA levels.
  
  
  OBJECTIVE
  (1) To assess usability and level of engagement with the Fitbit One and daily SMS-based prompts in a 6-week PA intervention, and (2) to examine whether use/ level of engagement with specific intervention components were associated with PA change.
  
  
  METHODS
  Data were analyzed from a randomized controlled trial that compared (1) a wearable sensor/ device (Fitbit One) plus SMS-based PA prompts, and (2) Fitbit One only, among overweight/ obese adults (N = 67). We calculated average scores from Likert-type response items that assessed usability and level of engagement with device features (e.g., tracker, website, mobile app, and SMS-based prompts), and assessed whether such factors were associated with change in steps/day (using Actigraph GT3X+).
  
  
  RESULTS
  Participants reported the Fitbit One was easy to use and the tracker helped to be more active. Those who used the Fitbit mobile app (36%) vs. those who did not (64%) had an increase in steps at 6-week follow-up, even after adjusting for previous web/app use: +545 steps/ day (SE= 265) vs. -28 steps/ day (SE= 242) (p= .04).
  
  
  CONCLUSIONS
  Level of engagement with the Fitbit One, particularly the mobile app, was associated with increased steps. Mobile apps can instantly display summaries of PA performance and could optimize self-regulation to activate change. More research is needed to determine whether such modalities might be cost-effective in future intervention research and practice.
authors: Moores Cancer Center, University of California, San Diego, La Jolla, California, USA; Graduate School of Public Health, San Diego State University, San Diego, California, USA; Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, USA.
authors: Julie B
authors: JB
authors: Wang
authors: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, USA.
authors: Janine K
authors: JK
authors: Cataldo
authors: Graduate School of Public Health, San Diego State University, San Diego, California, USA.
authors: Guadalupe X
authors: GX
authors: Ayala
authors: Moores Cancer Center, University of California, San Diego, La Jolla, California, USA.
authors: Loki
authors: L
authors: Natarajan
authors: Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin.
authors: Lisa A
authors: LA
authors: Cadmus-Bertram
authors: Moores Cancer Center, University of California, San Diego, La Jolla, California, USA.
authors: Martha M
authors: MM
authors: White
authors: Graduate School of Public Health, San Diego State University, San Diego, California, USA.
authors: Hala
authors: H
authors: Madanat
authors: Center for Wireless Population Health Systems, University of California, San Diego, La Jolla, California, USA.
authors: Jeanne F
authors: JF
authors: Nichols
authors: Moores Cancer Center, University of California, San Diego, La Jolla, California, USA.
authors: John P
authors: JP
authors: Pierce