Abstract
BACKGROUND: The COVID-19 outbreak might have had several effects on older adults; however, much of the previous research only included self-report, cross-sectional, and online-survey data in the early stage of the pandemic. We conducted a face-to-face survey before and after the COVID-19 pandemic and investigated the influence of the pandemic on several functions to distinguish between changes due to aging and changes due to the pandemic using a linear mixed model. METHODS: A total of 8 longitudinal surveys were conducted from 2016 to 2022. Physical function was assessed by weight, body mass index, body fat percentage, skeletal muscle mass index, calf circumference, grip strength, knee extension strength, the 5-times chair stand test, the timed up & go test and 5-m walking test. Functional capacity was measured using the Tokyo Metropolitan Institute of Gerontology index of competence, cognitive function was measured using the Trail Making Test - A, and mental health was measured using the Geriatric Depression Scale. RESULTS: Of a total of 73 participants, 51 (69.9%) were female. The mean age at first participation was 71.82 years (SD = 4.64). The results of the linear mixed model showed that lower-limb muscle strength and body fat percentage and cognitive function changed significantly before and after the pandemic, while grip strength, functional capacity, and mental health did not. CONCLUSIONS: The changes in these functions between before and after the pandemic might be attributed to the diminished opportunities for the independent older individuals to go out and engage in activities. Although functional capacity did not change, lower-limb muscle strength is important for functional independence. This decline might influence the functional capacity of these individuals in the future.