Active2Gether: Innovative and smart coaching strategies to promote physical activity: A research protocol

Background: Because 67.5 % of Dutch adults is not sufficiently physically active, effective innovative and smart physical activity (PA) promotion is warranted. The ubiquitous nature of smartphones offer new possibilities in PA promotion. Because of their built-in sensors and their ability to connect with the internet or third-party sensors, smartphones offer the possibility to monitor the behavior continuously, provide personalized, real-time and context specific feedback. Active2Gether (A2G) makes use of these possibilities and uniquely combines behavior change techniques with a model-based reasoning system in order to provide context specific coaching messages via smartphones to empower young adults to be and remain more physically active. Intervention: A2G is an app-based intervention that focuses on PA. The overall aim is to increase levels of weekly moderate-vigorous PA (MVPA). It surpasses existing apps as the coaching messages are theory- and literature- based and tailored to psychological and social concepts (e.g. outcome expectations, self-efficacy, social support) as well as to the physical and social context. The messages are based on proven behavior change techniques (e.g., self-monitoring, goal-setting, social-comparison) and are framed in an autonomy-supportive style. Furthermore, social network techniques will be used to influence beliefs and subsequent behavior. The intervention will start with an intake and an initial monitoring phase followed by 6 months of coaching. Methods: A 3-arm randomized trial with a baseline and three followup assessments will be carried out with approximately 150 young adults (18-30 years) in April 2015. PA and determinants of PA will be measured for two purposes: for the evaluation of the intervention and to serve as input for the personalized coaching messages. Actigraph accelerometers will measure weekly PA at baseline and at 3- and 6-months during and at 6 month after the intervention. Additionally, PA will continuously be assessed with a Fitbit One activity tracker. An extensive survey at baseline and the follow-ups will assess demographic characteristics and determinants of PA, while these determinants will repeatedly be measured during the intervention by means of short versions of existing questionnaires. Analysis: An outcome and a process evaluation will be conducted to estimate the effect of the A2G intervention on levels of weekly MVPA and to evaluate the underlying processes and mechanisms with mixed models and latent class growth analysis to explain the (lack of) effect.