Table 4 Interview topic guide for service users

In the topic guide, the term “App” is used to refer to the smartphone application under study.

Coherence:

1. Can I take you back to the ‘life before the trial (!)’ can you tell me about other strategies you have used in the past to increase your exercise

2. In what way was the idea of using the App different from these other strategies?

Cognitive participation is about engagement/‘buy in’:

1. How did you get involved - who told you about the idea?

2. Can you tell me why you thought it was right for you to get involved in the trial and to give this App a go?

Collective action is about actions and interactions that are required to use the intervention:

1. Now let’s focus on when you were starting to use the App itself, can you talk to me about starting to use it and the strategies that made it easy to do so and difficult to do so?

2. What was your sense of trust in the App as a device to support/stimulate your exercise routines?

3. Can you tell me about the different skills you needed to use the App? (develop some prompts here based on your knowledge of the different tasks that people had to perform to use the App)

4. What are your thoughts about using the App once/now that the trial is over?

Reflexive monitoring is about appraisal and evaluation:

1. Was using the application an effective and worthwhile way to improve your exercise?

2. How do you know?

3. Is it worthwhile to keep using the App now that the trial is over?