Randomized trial of a digital therapeutics intervention to enhance affective response during physical activity: Protocol for the eMOTION study.

Physical activity interventions often fail to address features of physical activity that may lead to maintaining behavior, such as emotional experiences during behavior. Although some people experience pleasure during physical activity, it can be extremely unpleasant for others. Affective mechanisms (e.g., affective responses during behavior, anticipated affect about future behavior, affectively-charged motivations for future behavior) can influence the likelihood of engaging in future behavior. Using an experimental medicine approach, this Phase 1 trial of the eMOTION intervention aims to test whether affective mechanisms can be experimentally manipulated in real-world settings and whether affective mechanisms mediate the intervention effects on physical activity behavior. Pathways will be tested through a daily digital therapeutics intervention delivered using interactive mobile technology among physically inactive adults with overweight or obesity. An affect-based condition will provide daily goals related to enjoyment and feeling good during physical activity. In contrast, an intensity-based condition will provide daily goals for heart rate targets to achieve during physical activity. Two enhancements to the affect-based condition are: (1) tailored activity type and context recommendations to satisfy personally important psychological needs and (2) savoring practices to increase the saliency of positive emotions during physical activity. An 18-week study will optimize the treatment effects using a factorial (within x between) cross-over design (N = 280). Affective mechanisms and physical activity will be measured using real-time ecological momentary assessment (EMA) and accelerometry, respectively. Overall, this study fulfills an explicit need for the systematic translation of basic behavioral science processes into health behavioral change strategies through early-stage intervention development. Trial Registration Number: NCT06570642.