Association between changes in implementation of group exercise and incidence of frailty among Japanese non-frail older adults: 2018 and 2020 surveys including the COVID-19 pandemic

The coronavirus disease 2019 (COVID-19) pandemic has hampered group exercise. We aimed to determine the relationship between group-exercise implementation status in 2018 and 2020 and the incidence of frailty in 2020, including the COVID-19 pandemic among older adults in Japan. This longitudinal study included older adults belonging to senior clubs, divided into four groups based on the continuity of group-exercise participation. Frailty was assessed using the Kihon Checklist, in which total scores of ≥8 points indicated frailty status. The relationship between group-exercise implementation status and the incidence of frailty was evaluated using Poisson regression with robust variance. Exercise time at the individual level in each group was analyzed using Wilcoxon signed-rank tests. Overall, 1,241 participants were included, in which 249 individuals (20.1%) developed frailty. Compared to older adults who continued group exercise, those who discontinued group exercise (adjusted relative risk: 1.70, 95% confidence interval: 1.26–2.30) were more likely to become frail. Regarding the median exercise time (interquartile range), older adults who discontinued group exercise showed a significant decrease, from 25.7 (12.9–51.7) min/day to 17.1 (6.4–30.0) min/day; but those who started group exercise showed a significant increase from 19.3 (6.4–41.4) min/day to 20.0 (6.4–47.6) min/day. Group exercise implementation status in 2018 and 2020 was associated with incidence of frailty in 2020, including the COVID-19 pandemic. It was concluded that supporting group exercise is important for the prevention of frailty, even under social restrictions owing to infectious diseases.