Abstract
Abstract Background Physical activity interventions using habit development may help people increase and then maintain physical activity increases over time. Enacting behavior in consistent contexts is a central component of habit development, yet its causal role in habit development in health behaviors has not been confirmed. Purpose This study tests the causal role of consistent context in habit development in health behavior, using a randomized control trial of a planning intervention to develop a walking habit in 127 insufficiently active, working, midlife adults in a real-world setting. Methods We compare participants who plan walking in consistent contexts with controls who plan walking in varied contexts and with controls not required to plan on a change in average daily steps (measured using an accelerometer) and inhabit automaticity during a 4-week intervention and at a 4-week follow-up. Results As expected, consistent and varied context planners increased walking during the intervention, but only consistent context planners developed (and maintained) habit automaticity. Counter to expectations, consistent context planners did not show walking maintenance. However, across conditions, participants who developed more habit automaticity during the intervention also maintained walking more (decreased less). Having a routine daily schedule moderated some effects. Notably, no-plan controls with greater routine developed more habit automaticity, mediated by walking in more consistent contexts. Conclusions This study confirms the causal role of consistent contexts in developing a walking habit, in a real-world setting, with an important but challenging population for physical activity interventions and identifies a facilitating condition common for many: a routine schedule.