Objective: This study aimed to investigate the change in objectively measured physical activity before and after the first of the state of emergency among community-dwelling older Japanese adults, as well as to investigate the difference in the changes according to the level of physical function.

Methods: A total of 78 community-dwelling older adults (≥ 65 years, mean age = 76.4 years, 55 women) were enrolled in this longitudinal study. The baseline survey was conducted from early September to early October 2019, and the follow-up survey was conducted from late August to early September 2020. Physical activity was measured through an accelerometer that the participants wore for a week. The number of steps (steps/day), light-intensity physical activity (LPA) (minutes/day), and moderate/vigorous-intensity physical activity (MVPA) (minutes/day) were calculated. Physical function was measured using the Short Physical Performance Battery. Wilcoxon’s signedrank test was used to investigate the changes in physical activity before and after the state of emergency. A forced entry linear regression analysis was used to investigate the difference in the changes according to the level of physical function.

Results: Forty-one older adults had high levels of physical function. The results suggested that steps, LPA, and MVPA decreased significantly three months after the state of emergency, compared to before the state of emergency (step change: -1096 steps/day [1st quartile, 3rd quartile: -1966, -55], LPA change: -6 minutes/day [-19, 1]，MVPA change: -5 minutes/day [-11, 0]). Furthermore, there was a larger decrease in steps and MVPA in older adults with high levels of physical function than those with low levels (steps: Β = -1276.6 [95% confidence interval = -2533.5 to -18.7], MVPA: Β = -11.5 [-20.7 to -2.2]). However, these associations disappeared after further adjustment for physical activity at baseline.

Conclusions: This study showed that objectively measured physical activity decreased significantly at three months after the state of emergency was lifted and that steps and MVPA decreased more among older adults with high levels of physical function. These findings may help establish guidelines for maintaining physical activity among older adults under the COVID-19 pandemic.

Objective: In 2009, “Must Read Papers 20 in Physical Activity and Exercise Epidemiology” was published in the journal, Research in Exercise Epidemiology. In the past decade, physical activity measurement, design, and analytical methods have been developed in the field of physical activity and exercise epidemiology; thus, research topics have evolved. Consequently, we selected “Must Read Papers 20 in Physical Activity and Exercise Epidemiology” among papers published after 2009 to provide useful information to researchers involved in this field.

Methods: This study was conducted as a research project approved by the Japanese Association of Exercise Epidemiology (JAEE) and titled as “Must Read Papers 20 in Physical Activity and Exercise Epidemiology 2nd edition”. First, we extracted candidate papers that were recommended by JAEE members and the current project team. Next, the project team members prespecified the selection criteria and finally selected 20 papers through discussion.

Results: We identified 39 candidate papers and selected 20 of them. Guidelines were excluded and the selected 20 papers included 12 observation studies, 5 intervention studies, 2 systematic reviews and meta-analyses, and 1 quasi-experimental study. Of them, 6 papers were from Japan.

Conclusion: We selected “Must Read Papers 20 in Physical Activity and Exercise Epidemiology: 2009–2018.”Methodologies and research themes in this field will continue to evolve in future; therefore, it is desirable to select and introduce important papers periodically.