An Adaptive Physical Activity Intervention for Overweight Adults

The purpose of this study is to develop and evaluate an adaptive shaping intervention based on Behavioral Economics and Operant principles to promote physical activity behaviors (adaptive group) and compare to a static physical activity intervention (static group) using a two-group randomized controlled trial design. Participants will include 20 overweight men and women (BMI 25-35 kg/m2) between 18 to 55 years. Both groups will receive the following components: 1) a pedometer, 2) self-monitoring of physical activity, 3) brief educational materials, 4) motivational prompts, 5) physical activity goals, and 6) small financial incentives. The Adaptive Intervention (AI) group will receive adaptive goals and feedback based on percentiles and a "moving" window of their recent physical activity, with incentives linked to goal attainment. Comparison intervention participants will receive the static 10,000 steps per day goal, with matching incentive amounts but without incentives linked to goal attainment. The study will compare differences in goal setting and shaping procedures that aim to increase physical activity behavior. Primary aims include: 1. To determine whether physical activity (pedometer-measured steps/day) in both the Adaptive and Static interventions increased compared to their respective baselines. Hypothesis: Both the adaptive and static interventions will result in increased physical activity over 6 months. 2. To evaluate whether the Adaptive Intervention results in greater change in physical activity (pedometer-measured steps/day) compared to the Static Intervention. Hypothesis: The adaptive intervention will result in significantly greater physical activity, measured by pedometer, compared to the static intervention over 6 months. 3. To assess participants' satisfaction with the overall program. Hypothesis: Adaptive Intervention participants will report greater overall satisfaction with the intervention than the Static Intervention participants.