title: Feasibility and Effectiveness of Using Wearable Activity Trackers in Youth: A Systematic Review.
abstract: BACKGROUND
  The proliferation and popularity of wearable activity trackers (eg, Fitbit, Jawbone, Misfit) may present an opportunity to integrate such technology into physical activity interventions. While several systematic reviews have reported intervention effects of using wearable activity trackers on adults' physical activity levels, none to date have focused specifically on children and adolescents.
  
  
  OBJECTIVE
  The aim of this review was to examine the effectiveness of wearable activity trackers as a tool for increasing children's and adolescents' physical activity levels. We also examined the feasibility of using such technology in younger populations (age range 5-19 years).
  
  
  METHODS
  We conducted a systematic search of 5 electronic databases, reference lists, and personal archives to identify articles published up until August 2016 that met the inclusion criteria. Articles were included if they (1) specifically examined the use of a wearable device within an intervention or a feasibility study; (2) included participants aged 5-19 years old; (3) had a measure of physical activity as an outcome variable for intervention studies; (4) reported process data concerning the feasibility of the device in feasibility studies; and (5) were published in English. Data were analyzed in August 2016.
  
  
  RESULTS
  In total, we identified and analyzed 5 studies (3 intervention, 2 feasibility). Intervention delivery ranged from 19 days to 3 months, with only 1 study using a randomized controlled trial design. Wearable activity trackers were typically combined with other intervention approaches such as goal setting and researcher feedback. While intervention effects were generally positive, the reported differences were largely nonsignificant. The feasibility studies indicated that monitor comfort and design and feedback features were important factors to children and adolescents.
  
  
  CONCLUSIONS
  There is a paucity of research concerning the effectiveness and feasibility of wearable activity trackers as a tool for increasing children's and adolescents' physical activity levels. While there are some preliminary data to suggest these devices may have the potential to increase activity levels through self-monitoring and goal setting in the short term, more research is needed to establish longer-term effects on behavior.
authors.affiliation: Deakin University, Geelong, Australia, Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, .
authors.forename: Nicola D
authors.identifier: http://orcid.org/0000-0001-5713-3515
authors.initials: ND
authors.lastname: Ridgers
authors.affiliation: Applied Sports Science Technology and Medicine Research Centre (A-STEM), College of Engineering, Swansea University, Swansea, United Kingdom.
authors.forename: Melitta A
authors.identifier: http://orcid.org/0000-0003-0813-7477
authors.initials: MA
authors.lastname: McNarry
authors.affiliation: Applied Sports Science Technology and Medicine Research Centre (A-STEM), College of Engineering, Swansea University, Swansea, United Kingdom.
authors.forename: Kelly A
authors.identifier: http://orcid.org/0000-0003-0355-6357
authors.initials: KA
authors.lastname: Mackintosh
keywords: behaviour change; electronic activity monitor; mHealth; physical activity