Changes in physical activity and rest-activity circadian rhythm among Hong Kong community aged population before and during COVID-19

This study aims to determine the changes in physical activity and actigraphy-measured rest-activity circadian rhythm among Hong Kong community aged population before and during the outbreak of COVID-19. This is a three repeated measure population-based cross-sectional study. We recruited community older men aged > 60 years in three periods of the COVID-19 outbreak in Hong Kong, i.e., before the COVID-19 outbreak (2 July 2019-8 January 2020), between the 2nd and 3rd waves of COVID-19 (23 June 2020-9 July 2020), and during the 3rd wave of COVID-19 (15 September 2020-29 September 2020). Participants reported detailed information on their physical activity habits using the International Physical Activity Questionnaire and wore actigraphs continuously for 7 days (168 h). The actigraph data were then transferred to four rest-activity circadian rhythm parameters: midline statistic of rhythm (MESOR), amplitude, acrophase and percent rhythm. Multivariate logistic regression was performed to estimate the association of period effect of COVID-19 on physical activity and rest-activity circadian rhythm parameters. Among the 242 community older men, 106 (43.8%) of them were recruited before the COVID-19 outbreak, 66 (27.3%) were recruited between the 2nd and 3rd waves of COVID-19, and 70 (28.9%) were recruited during the late phase of the 3rd wave of COVID-19. Compared with those recruited before COVID-19, participants recruited between the 2nd and 3rd waves of COVID-19 had lower physical activity (adjusted odds ratio (AOR) = 2.03, 95% confidence interval (95%CI) =1.05-3.93), MESOR (AOR = 2.05, 95%CI = 1.01-4.18), and amplitude (AOR = 1.91, 95%CI = 0.95-3.83). There was no difference in physical activity or circadian rhythm parameters between subjects recruited before and during the late phase of the 3rd wave. This study found that the effect of COVID-19 on physical activity and rest-activity circadian rhythm for the community people may be short-term, indicating strong resilience of the community population. Although maintaining physical activity are encouraged for the older adults to sustain good health, a rebound in their physical activity may be a sign for the next wave of outbreak if insufficient social distancing and population protection are facilitated.