Using real-time data capture to examine affective mechanisms as mediators of physical activity adherence in interventions

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PROJECT SUMMARY Cancer remains a leading cause of mortality. Approximately 42% of cancer cases in the U.S. are potentially avoidable, including 15% caused by excess body weight and physical inactivity. However, most U.S. adults are physically inactive. Public health guidelines recommend combinations of activity intensity, frequency, and duration to achieve a “dose” of at least 150 min/week of moderate-to-vigorous intensity physical activity. While this approach produces health benefits, it fails to address features of physical activity that may lead to sustainability such as emotional experiences during behavior. To promote long-term maintenance, evidence- based strategies are needed describing how affect can be incorporated into physical activity recommendations. Although some people experience pleasure during physical activity, it can be extremely unpleasant for others, especially among overweight and inactive individuals. Incentive salience theory proposes affective responses (e.g., liking, disliking) during behavior influence affectively-charged motivations (e.g., wanting, dreading) to engage in future behaviors. However, whether modifying these affective mechanisms is a useful intervention approach for increasing for physical activity is unknown. Using an experimental medicine approach, this Phase 1 trial will test whether affective mechanisms can be experimentally manipulated in real-world settings and whether affective mechanisms mediate the effects of interventions on physical activity behavior among adults who are at elevated cancer risk. Pathways will be tested through a daily self- regulation intervention delivered using interactive mobile technology among physically inactive adults (18-65 years) who are overweight or obese. In an affect-based condition, self-regulation strategies will target daily goals related to enjoyment and feeling good during physical activity. In contrast, an intensity-based condition will target daily heart rate goals 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. A Formative study (N=36) will iteratively test and refine the treatment implementation in terms of acceptability and feasibility of the content, delivery, usage, and engagement. Subsequently, a 16-week Comparison study (N=280) will optimize the treatment effects using a factorial (within x between) cross-over design. Affective mechanisms and physical activity will be measured in daily life using real-time ecological momentary assessment (EMA) and accelerometry, respectively. Specific aims are (1) test treatments to experimentally manipulate affective mechanisms, (2) determine whether affective mechanisms mediate effects of treatments on physical activity, and (3) explore cross-person and cross-situation moderating effects such as self-regulatory capacity and situational factors. Overall, this study is impactful because it fulfills an explicit need for the systematic translation of fundamental behavioral science processes into new health behavioral interventions.