JMIR Publications

ABSTRACT

Background:

App-based mHealth exercise interventions have the potential to motivate individuals to engage in more physical activity (PA). According to Fogg’s behavioral model, it is important the individual receives prompts at the ‘right’ time in order to be successfully persuaded into PA, coined as just-in-time (JIT) interventions. The PAUL app is among the first to include two types of JIT prompts, namely JIT adaptive reminder messages to initiate a run or walk and JIT strength exercise prompts during a walk or run (containing location-based instruction video’s). This paper reports on the feasibility of the PAUL app and its JIT prompts.

Objective:

The main objective of this study is to examine user experience, app engagement, user’s perceptions and opinions regarding the PAUL app and its JIT prompts and to explore changes in PA behavior, intrinsic motivation and perceived capability of PA behavior of the participants.

Methods:

Two versions of the closed-beta version of the PAUL app were evaluated, a basic version (Basic PAUL) and a just-it-time adaptive version (Smart PAUL). Both apps send JIT exercise prompts, but the versions differ in that the Smart PAUL sends JIT adaptive reminder messages to initiate the running or walking behavior, while the Basic PAUL app sends reminder messages at randomized times. Twenty-three participants were randomized into one of the two intervention arms. The PA behavior (accelerometer measured), intrinsic motivation and perceived capability for PA behavior were measured pre- and post-intervention. After the intervention, participants were also asked to complete a questionnaire on user experience, and they were invited for an exit interview to assess the user perceptions and opinions of the app in depth.

Results:

No differences for PA behavior were observed (Z = -1.433, p = 0.084), but the intrinsic motivation for running, walking and performing strength exercises significantly increased (Z = -3.342, p <.001 and Z = -1.821, p = 0.035, respectively). Furthermore, participants increased their perceived capability for the performance of strength exercises (Z = 2.231, p = 0.012), but not for walking and running (Z = -1.221, p = 0.116). The interviews indicated that participants were enthusiastic about the strength exercise prompts. They were perceived as personal, fun and relevant for their health. The reminders were perceived as important initiators for PA, but participants from both apps explained that the reminder messages were often not sent at times they could exercise. Although participants were enthusiastic about the functionalities of the app, technical issues resulted in a low user experience.

Conclusions:

The preliminary findings suggest that the PAUL apps are promising, innovative interventions to promote PA. Users perceived the strength exercise prompts as a valuable addition to exercise apps. However, to be a feasible intervention, the app must be more stable. Clinical Trial: Netherlands Trial Register (trial ID: NL8166)