The Tsuru Longitudinal Study: Design and Profile of Participants.

BACKGROUND: Physical activity, sedentary behaviour, and sleep (collectively referred to as physical behaviours) are promising preventive factors for adverse health outcomes. However, most previous studies have relied on subjective measures assessed at a single time point, which fail to capture changes in physical behaviours over time and can introduce measurement bias. METHODS: The Tsuru Longitudinal Study is a cohort study of older adults aged ≥65 years living in Tsuru, Yamanashi, Japan. The study includes mail surveys conducted in 2016, 2018, 2019, 2022, 2024, and 2026, accelerometer-based assessments in 2024 and 2026, and linked data (Long-Term Care Insurance and Basic Resident Registration System), which enable the examination of associations of trajectories of physical behaviours and device-measured physical behaviours with various health outcomes. RESULTS: While the 2026 survey is currently underway, the number of respondents (response rate) to the surveys in 2018, 2019, 2022, and 2024 was 4857 (72.4%), 4941 (74.1%), 5459 (74.6%), and 4106 (63.6%), respectively. A total of 779 participants completed the accelerometer-based assessment. At baseline of the mail survey, men were more likely than women to have lower educational attainment and less favourable health characteristics. Participants who completed the physical behaviour assessment were more likely to be older, have higher socioeconomic status, be more physically active, be more socially engaged, and be less likely to have depression. CONCLUSIONS: This cohort study is expected to provide evidence on the health effects of physical behaviours and inform strategies to promote successful ageing.