i2be: a randomized controlled trial protocol for an app-based physical activity intervention

Physical activity is an important determinant of cardiovascular health. Therefore, health behavior interventions targeting physical activity are highly warranted. Most interventions have limited and short-term effects, likely because they fail to bridge the intention-behavior gap. The current study will test a dual system theory- and evidence-based e-health intervention, and additionally, provide important insight into the contribution of volitional and automatic processes in bridging the intention-behavior gap and achieving sufficient and sustained physical activity.

The effectiveness of the intervention will be tested using a three-arm randomized controlled trial implemented through an app. The intervention is based on the integrated behavior change model, describing physical activity as the result of motivational, volitional, and automatic processes. The study design will allow insight into the contribution of volitional and automatic processes in bridging the intention-behavior gap.

Following i2be app registration and stratification on baseline factors, participants will be randomly allocated (1:1:1) in-app to the control group, treatment 1, or treatment 2. The control group receives the module ‘Get Informed’ consisting of usual care, i.e. knowledge provision. In addition to the module ‘Get Informed’, treatment 1 receives the module ‘Get Motivated’ (targeting motivational processes), consisting of the behavior change technique (BCT) of motivational interviewing-based counselling. In addition to the modules ‘Get Informed’ and ‘Get Motivated’, treatment 2 receives the module ‘Get Activated’ (targeting volitional processes), consisting of the BCTs of action planning training and reminders, coping planning training, and commitment training, and the module ‘Get Energized’ (targeting automatic processes), consisting of the BCTs of mindfulness-based stress reduction and positive psychology. Engagement with the fully automated app is incentivized through primary task support, dialogue support, and psychological and tangible rewards.

The primary outcome is objectively measured weekly minutes of moderate-to-vigorous physical activity. Secondary outcomes include objectively measured (resting heart rate) and self-reported physiology measurements (body mass index, waist-to-hip-ratio, cardiorespiratory fitness), as well as subjective well-being. Tertiary outcomes include self-reported mechanism of action variables in order to assess the mechanisms underlying the effects of BCTs. Objectively measured outcomes will be captured by a Fitbit device (Fitbit Inspire 2), and all other outcomes measures will be self-reported into the i2be app. Outcome measures will be assessed at baseline, immediately post-intervention, at 3 months follow-up, and at 12 months follow-up. Weekly minutes of moderate-to-vigorous physical activity will additionally be assessed at the intervention midpoint. Effectiveness will be determined by a modified intention-to-treat analysis.

i2be has been developed in collaboration with Avegen, a digital health company that aims to empower individuals to take control of their health and has specific expertise in the areas of cardiovascular health, maternal health, and individualized care. Avegen was responsible for the programming of the app, and the name, logo and branding of the app.

The main test of i2be is the test between treatment 2 versus control, expecting higher weekly minutes of moderate-to-vigorous physical activity in the former. Second, we will test the difference between treatment 2 and treatment 1, expecting higher weekly minutes of moderate-to-vigorous physical activity in the former. Third, we will test the difference between treatment 1 and control, expecting higher weekly minutes of moderate-to-vigorous physical activity in the former.

Outcome measures will be assessed at baseline, immediately post-intervention, at 3 months follow-up, and at 12 months follow-up.

Intervention duration is 8 weeks. All participants use the i2be app and their Fitbit device, and receive the module ‘Get Informed’ consisting of usual care (standard treatment).

In addition to receiving standard treatment, treatment 1 receives the module ‘Get Motivated’ (targeting motivational processes), consisting of the behavior change technique (BCT) of motivational interviewing-based counselling.

In addition to receiving standard treatment and the module ‘Get Motivated’, treatment 2 receives the module ‘Get Activated’ (targeting volitional processes), consisting of the BCTs of action planning training and reminders, coping planning training, and commitment training. Furthermore, treatment 2 receives the module ‘Get Energized’ (targeting automatic processes), consisting of the BCTs of mindfulness-based stress reduction and positive psychology.