Melanie I Stuckey, Shawn W Carter, Emily Knight

Lack of physical activity is a global public health issue. Behavioral change interventions utilizing smartphone applications (apps) are considered a potential solution. The purpose of this literature review was to: 1) determine whether smartphone-based interventions encourage the initiation of, and participation in, physical activity; 2) explore the success of interventions in different populations; and 3) examine the key factors of the interventions that successfully encouraged physical activity. Eight databases (Medline, Scopus, EBM Reviews-Cochrane Central Register of Controlled Trials, EBM Reviews-Cochrane Database of Systematic Reviews, PsycInfo, SportDISCUS, CINAHL, and EMBASE) were searched and studies reporting physical activity outcomes following interventions using smartphone apps in adults were included in the narrative review. Results were mixed with eight studies reporting increased physical activity and ten reporting no change. Interventions did not appear to be successful in specific populations defined by age, sex, country, or clinical diagnosis. There was no conclusive evidence that a specific behavioral theory or behavioral change technique was superior in eliciting behavioral change. The literature remains limited primarily to short-term studies, many of which are underpowered feasibility or pilot studies; therefore, many knowledge gaps regarding the effectiveness of smartphone apps in encouraging physical activity remain. Robust studies that can accommodate the fast pace of the technology industry are needed to examine outcomes in large populations.