Making physical activity a walk in the park The development and evaluation of a smartphone app-based just-in-time adaptive intervention to promote walking

Physical inactivity is a significant risk factor for non-communicable diseases, particularly affecting socioeconomically disadvantaged populations. This dissertation focuses on the importance of walking to combat inactivity. While walking apps have the potential to stimulate regular physical activity, they are underutilized by individuals from lower socioeconomic backgrounds.
Using the Technology Acceptance Model, the first part of the dissertation explores factors influencing walking app use intention and usage across different socioeconomic segments. It highlights perceived ease of use and usefulness as key factors in driving walking app adoption, particularly for individuals with no prior app experience and lower socioeconomic position.
Building on these findings, the second part of the dissertation introduces SNapp, an app-based just-in-time adaptive intervention designed to promote walking among socioeconomically disadvantaged Dutch adults. SNapp incorporates health behavior theory and dynamically tailors coaching content to individual users based on their content preferences, step count levels, and proximity to green spaces suitable for walking. A twelve-month randomized controlled trial evaluates the intervention's effects, showing positive outcomes only for users who perceived the app as useful for tracking and achieving daily walking goals.
This dissertation highlights the potential effectiveness of walking apps in promoting physical activity, contingent on individual perceptions of ease of use and usefulness. To maximize impact, developers should collaborate with interdisciplinary teams, employ iterative development processes, and leverage advanced AI techniques to enhance these user perceptions. By incorporating these insights, developers can design more effective interventions to combat physical inactivity and associated health risks, particularly among socioeconomically disadvantaged populations.