Longitudinal study of changes in daily and hourly steps during the COVID-19 pandemic in Japan

Abstract

Background: The impact of the coronavirus disease 2019 (COVID-19) pandemic on changes in physical activity, particularly diurnal patterns, remains unclear. We investigated temporal changes in daily steps before and after the emergency declaration in Japan during the COVID-19 pandemic.

Methods: Nationwide de-identified data from users of a physical activity-promoting smartphone application were collected. Daily and hourly steps were measured using smartphones from January 2019 to September 2020. Linear mixed models estimated changes in steps before, during, and after the April and May 2020 emergency declaration relative to 2019, involving 3,480 users (daily steps) and 3,402 users (hourly steps).

Results: Compared to the 2019 baseline, daily steps decreased during the emergency declaration (April: -1115 steps/day [95% confidence interval, -1233 to -998]) and only partly recovered thereafter (July: -496 steps/day [-609, -382]). This decline was greater among participants aged 18–39 (P for interaction < 0.05). By time of day, steps significantly decreased during weekday morning commutes and at night (e.g., 21:00: -136 steps/hour [-153, -119]) and during weekend days and late evenings (e.g., 12:00: -173 steps/hour [-196, -151]). After the declaration was lifted, step counts recovered but were still lower at night (e.g., 21:00 on weekends: -120 steps/hour [-135, -106]).

Conclusions: Daily steps decreased after the emergency COVID-19 declaration in Japan. Even after the emergency period ended, there was a persistent population-level decline in daily steps, with a partial shift in the diurnal pattern. Efforts are needed not only to restore but also to further promote physical activity beyond pre-pandemic levels.