Mechanisms of physical activity behavior change in an incentive-based intervention: Mediation analysis.

The physical activity loyalty (PAL) scheme was a cluster randomized controlled trial of a 6-month complex intervention targeting workplace physical activity. Financial incentives were incorporated in an evidence-based behavior change program, including self-regulation techniques. This article examines short-term (< 6 months) and long-term (≥ 6 months) mediation effects on physical activity. Participants included 853 adults (457 intervention, 396 control). Physical activity was objectively assessed using pedometers at baseline and at 6 and 12 months. Hypothesized short-term mediators (e.g., self-efficacy, intentions) were assessed at baseline and 4 weeks. Hypothesized long-term mediators (e.g., habit, intrinsic motivation) were assessed at baseline and 6 months. Mediation models employed the structural equation modeling product-of-coefficients approach. Intervention participants experienced significant decreases in 6-month pedometer steps/day versus controls ( Most examined mediators were nonsignificant, and mediation analyses did not explain decreases in physical activity for interventions versus controls. Results show that, contrary to self-determination theory hypotheses, intrinsic motivation is not necessarily adversely impacted if financial incentives are embedded in a complex intervention. (PsycINFO Database Record (c) 2020 APA, all rights reserved).