Studies show that centenarians' physical function and activities of daily living (ADL) levels improved recently. However, it is unclear whether this positive impact has been altered due to COVID-19, causing reduced ADL. This study had two objectives: 1) to investigate whether the physical function of Japanese centenarians has improved over time, and 2) to examine the impact of COVID-19 on centenarians.

The data were collected from research conducted in Kyotango City from 2014 to the present. Kyotango City Hall collected data, including the functional status of all centenarians who reached 100 years of age every year. In this study, we divided nine-year cohort into three periods: 2014–2016 (P1), 2017–2019 (P2), and 2020–2022 (P3). The participation rates were 89 % (n = 100), 78 % (n = 90), and 74 % (n = 114), respectively.

The centenarians’ ADL declined as the cohort aged. For basic activities of daily living (BADL), independent participants and female centenarians exhibited a proportional increase from P1 to P2 and a proportional decrease from P2 to P3, whereas male centenarians did not experience this trend. Concerning mobility, only the proportion of bedridden centenarians decreased over the three periods. Statistically significant differences in the trends of female centenarians with robust mobility and those with weak mobility were obtained in the three periods.

The proportion of independent female centenarians declined with cohort aged in both BADL and Mobility. The opposite is true for male centenarians. This phenomenon was not affected by COVID-19.