ADAPT Micro-Randomized Trial

The goal of this study is to collect quantitative and qualitative data that can be used to optimize the HeartSteps mHealth intervention for physical activity. The current version of the intervention is intended to help patients with heart disease increase and maintain their physical activity long-term. To accomplish this goal, a 3-month pilot micro-randomized trial (MRT) will be conducted with 60 patients who are currently completing or have recently completed phase II cardiac rehabilitation (CR). The core of the study participation is the use of the HeartSteps intervention over the course of 3 months. This includes wearing the Fitbit Charge activity tracker during waking hours and using the HeartSteps intervention to support their efforts to be active. The HeartSteps intervention consists of two sets of intervention components: (1) components intended to improve participants' affective associations with physical activity, including activity suggestions designed to to trigger positive feelings and associate them with being active, and prompts to bring their awareness to intrinsically motivating aspects of being active; and (2) components that target reflective self-regulatory processes, including graphs for self-monitoring, prompts to plan activity, and weekly activity goals. How exactly, and how much, participants will use HeartSteps will not be prescribed since our goal is to understand naturalistic trajectory of engagement with the intervention.