Rapid technological development has challenged researchers developing mobile moderate-to-vigorous physical activity (MVPA) interventions. This 12-week randomized factorial intervention aimed to determine the individual and combined impact of a self-monitoring smartphone-app (tracking, feedback, education) and two theory-based modules (goal-setting, points-based feedback) on MVPA, key psychosocial outcomes, and application usage. Adults (N = 116; M age = 41.38 ± 7.57) received (1) a basic self-monitoring app, (2) the basic app plus goal setting, (3) the basic app plus points-based feedback, or (4) the basic app plus both modules. All individuals increased MVPA by more than 11 daily minutes. Those with points-based feedback demonstrated still higher levels of MVPA and more favorable psychosocial and app usage outcomes across the intervention. Those with access to in-app goal setting had higher levels of app usage relative to those without the component. It is imperative that effective digital intervention "ingredients" are identified, and these findings provide early evidence to this effect. Trial Registration clinicaltrials.gov identifier NCT02592590.
Keywords: Health behavior; Physical activity; Technology; Theory.