Feasibility and outcomes from development and testing of a health behavior theory-based fitness app

Research studies suggest that health behavior theory-informed approaches in behavior change interventions are needed to evoke improved health outcomes. This is specifically noted in mobile fitness applications (“apps”), for which the literature indicates a gap between theory use and app development. The purpose of this study was to develop and test a theory-based app to determine if various constructs, in the form of app features, could be manipulated to elicit behavior change. The hypothesis was that the version of the app that included all constructs of TPB would be most impactful at increasing behavioral intention and the actual behavior of engaging in more physical activity. A fitness app was developed with Theory of Planned Behavior (TPB) constructs used to inform app features. The app basic features included behavior tracking, pre-programmed workouts, and a user-friendly interface. The app had seven variations with certain app features, designed to address TPB constructs, available or not available, to the user. After completing the pre-test, 53 participants received a version of the app at random and were not aware of other possible app version features. After eight weeks of using the app, participants completed a post-test (N=44). Pre- and post-test surveys measured TPB constructs. The participants were primarily white women ages 18–24. Due low enrollment and attrition, control participants were removed from the analysis and all versions of the app were collapsed into one group for pre- post-test comparison. Between pre- and post-test, across all app versions with features addressing TPB constructs, “intention to exercise using a fitness app” increased significantly [t(40) =3.88, P<0.001]. However, overall “exercise intention” and actual reported exercise frequency did not change. Although the theory-based app did evoke change in behavioral intention with regard to using a fitness app, this did not translate to reported increases in exercise frequency. Though the app incorporated a health behavior change theory, the app did not elicit behavior change, which may be due to sample size or other factors that have yet to be elucidated. There is much room for improvement in fitness app development, such as translating intention to behavior, testing other health behavior theories, and determining the best ways to develop app features to represent theoretical constructs.