A recipe for an outdoor physical activity application: Designing context aware interventions for healthy urban residents

Abstract

A substantial proportion of Dutch adults fail to meet the physical activity (PA) guidelines, including both moderate-intensity PA and strength training, despite their importance for maintaining health and preventing disease. Mobile PA applications (PA apps) offer scalable and cost-effective opportunities to promote healthier behaviours. However, previous studies have demonstrated that the effectiveness of PA apps remains inconsistent. A possible explanation is the suboptimal selection, design and technical implementation of persuasive strategies (such as rewards and goal setting) embedded in these apps to encourage behaviour change. While some studies suggest that certain persuasive strategies are more effective than others, no clear consensus has been reached. One promising approach is the implementation of context-aware support, defined as interventions tailored to the time, location, and context of users. However, little is known about how to effectively operationalise such support. Therefore, this thesis addresses the research question: How can personalised and context-aware support in mobile PA apps be designed and implemented to increase PA behaviour of healthy adults living in large cities in the Netherlands? To this end, the PAUL app was developed and tested. The findings demonstrate that potential end-users prefer personalised, health-guideline-related feedback, as well as simple, clear metrics such as step count and calories burned. In contrast, social comparison and competitive functionalities were less preferred. Users also favoured receiving reminders to engage in PA at personally relevant times. The timing of the reminders is potentially even more important than their content. As individuals differ in their preferred timing, Just-in-Time Adaptive Interventions (JITAI) are likely to be most effective as they can adapt their timing to the individuals’ personal contexts and preferences. A novel context-aware app functionality was also introduced. This functionality delivered location-specific prompts for strength exercises during recreational walking or running activities, supported by short instructional videos. This functionality was positively received by the users. Suitable for these prompts are likely environments that are perceived as safe, appropriate for exercise, and sufficiently private. Notably, individuals differ in their perception of ‘safe’ locations, further emphasising the importance of personalisation and context-aware support. These results indicate that the design and implementation of context-aware persuasive strategies are important for both the user engagement with PA apps and their effectiveness. However, the scoping review conducted in this thesis revealed substantial heterogeneity in the design and technical implementation of persuasive strategies, while only a limited number of studies have systematically examined the effects of these varying designs and operationalisations. Therefore, the main conclusion of this doctoral thesis is that, to advance the development of effective mobile PA apps, research must move beyond identifying which persuasive strategies should be included in the app, and instead also examine how these strategies should be designed and implemented. Promising approaches include Just-in-Time Adaptive reminder messages and Just-in-Time strength exercise prompts. The ability to learn the proper timing for behavioural prompts, alongside technical reliability, is critical for effectiveness.