Introduction
Only a small percentage of U.S. adults meet national physical activity (PA) guidelines based on objective measures [A recent narrative review of studies that examined how neighborhood environments interact with individual-level PA interventions found mixed results [Notably, studies examining interactions between the objectively-measured built environment and physical activity have either been mainly retrospective, cross-sectional, or prospective observational studies [At least three challenges have made testing for potentiation between the built environment and individual-level PA interventions difficult. First, one ideally needs to observe that the intervention effectively increases PA. Second, the study needs to be designed a priori to ensure sufficient range (i.e., variability) in the built environment measures. Because randomizing participants to neighborhoods would not be possible, many observational studies recruited participants based on levels of walkability, which have had much better success in showing the effects of urban form on physical activity than convenience samples [The current study addresses many of these issues. We previously reported on the efficacy of an mHealth intervention’s components for improving free-living MVPA [