Interaction effect of neighborhood walkability and season on adults' step count

Introduction: Walking activity shows differences by season or neighborhood walkability (NW). Elucidation of interactions between season and NW may contribute to the identification of highrisk populations. We examined the interaction effect of objectively measured NW and season on step counts in a large population. Methods: We analyzed consecutively measured pedometer data collected from 47,233 adults aged 40-79 years who participated in the Yokohama Walking Point Program. Step counts in May 2018 (spring) and August (summer) as well as October (autumn) and January 2019 (winter) were compared. Neighborhoods (postal code areas) were classified into quartiles for each of the three NW variables (i.e., distance to the nearest railway station, population density, and street intersection density). The interaction effect of each of the NW variables and season on step count was examined using mixed-effects linear regression analyses. Results: The average daily step counts were fewer in summer and winter and higher in areas near the railway stations and areas with higher population density. We found a significant interaction effect of NW and season on step counts in summer. Participants residing in areas farther from the nearest railway station (P < 0.001) or areas with the lowest quartile of population or intersection density (P = 0.001, 0.030, respectively) showed a decline in step counts in summer by up to 118.4 steps/day compared with participants in other areas, which was not found when comparing the step counts between winter and autumn. Conclusions: NW and season showed interaction effect on adults' step counts, indicating that in low walkable areas where residents generally walk less, their step counts decrease more in summer when compared with those in other areas; however, this was not the case in winter. Promoting walking in the less walkable neighborhoods, specifically during summer, is required.