Effects of Goal Type and Reinforcement Type on Self-Reported Domain-Specific Walking Among Inactive Adults: 2×2 Factorial Randomized Controlled Trial (Preprint)

Abstract

BACKGROUND WalkIT Arizona was a 2x2 factorial trial examining the effects of goal type (adaptive vs. static) and reinforcement (immediate vs. delayed) to increase moderate to vigorous physical activity (MVPA) among insufficiently active adults. The 12-month intervention combined mobile health (mHealth) technology with behavioral strategies to test scalable population-health approaches to increasing MVPA. Self-reported physical activity provided domain-specific information to help contextualize the intervention effects. OBJECTIVE This study reports secondary outcomes of self-reported walking for transportation and leisure over the course of the 12-month WalkIT intervention. METHODS Participants (N=512, 64% women, 19-60 yrs old, 84% Non-Hispanic White, 18% Hispanic) were randomized into goal type and reinforcement type interventions. The IPAQ-long form assessed walking for transportation and leisure at baseline, months 6 and 12 during the intervention. Negative binomial hurdle models examined the effects of goal and reinforcement types on 1) odds of reporting any (versus no) walking and 2) total reported minutes of walking/week, adjusting for neighborhood walkability and socioeconomic status. Separate analyses were conducted for transportation and leisure walking, and with complete cases and using multiple imputation. RESULTS All intervention groups reported increased walking at 12-months relative to baseline. Effects of the intervention differed by domain: a significant three-way goal by reinforcement by time interaction was observed for total minutes of leisure walking/week, whereas time was the only significant factor that contributed to transportation walking. A sensitivity analysis indicated minimal differences between complete case analysis and multiple imputation. CONCLUSIONS This study is the first to report differential effects of adaptive vs. static goals for self-reported walking by domain. Results support the premise that individual level PA-interventions are domain and context-specific and may be helpful in guiding further intervention refinement. CLINICALTRIAL Preregistered at clinicaltrials.gov (NCT02717663). INTERNATIONAL REGISTERED REPORT RR2-10.1016/j.cct.2019.05.001