Age-related longitudinal changes in accelerometer-measured physical activity in community-dwelling older adults in Japan

Background: Understanding age-related changes in physical activity (PA) patterns may be useful in the development of public health recommendations tailored to older adults. However, limited data are available on how intensity-specific PA changes with age.
Purpose: This longitudinal study aimed to quantify changes in older adult’s PA measured by accelerometry over a 4-year period.
Methods: Participants were 298 randomly selected older Japanese adults (48.0% men, 65–84 years at baseline, follow-up rate 56%) who provided valid accelerometer data (Active style Pro HJA-750C, Omron, Kyoto) for both baseline in 2017 and follow-up in 2021. Compositional data analysis was used to examine changes in sedentary behavior (SB), light-intensity PA (LPA) and moderate-to-vigorous PA (MVPA), taking into account the co-dependence of time use domains.
Results: Mean daily time spent in SB, LPA and MVPA at baseline was 477, 347 and 57 minutes respectively. Overall, SB increased and PA decreased over the four-year period, with the largest relative change in MVPA regardless of gender (men: 6.6% to 5.4%, women: 6.0% to 4.9%). Mean time spent in MVPA decreased by approximately 10 minutes per day. The decline in LPA was less for women than for men.
Conclusions: The decline in PA with age was significant, with MVPA decreasing by approximately 10 minutes per day over four years. On the other hand, LPA was relatively maintained in women, suggesting that this helps women maintain PA in the later years of life.
Funding: Supported by grant from ‘the Policy Research Institute, Ministry of Agriculture, Forestry and Fisheries in Japan’ and ‘the Pfizer Health Research Foundation’, by JSPS KAKENHI Grant Number 16H03249, 17K19794, 18K10829, 19H03910, and 21K17551, and by the Health and Labor Sciences Research Grant 22FA1005 and 22FA2001.