Longitudinal Changes of Physical Activity and Sedentary Time in the Middle-Aged and Older Japanese Population: The Hisayama Study

Background: The purpose of this study was to describe changes in physical activity volumes and sedentary time over 3 years in the middle-aged and older Japanese population. Methods: Study participants included 1151 Japanese community-dwelling residents aged >= 40 years in 2009 who underwent 2 sets of health examinations (2009 and 2012). Using a triaxial accelerometer, longitudinal changes in sedentary time, light physical activity volume, moderate to vigorous physical activity volume, number of steps, and total physical activity volume were evaluated according to sex, age (40-49, 50-59, 60-69, 70-79, and >= 80 y), and obese (nonobese and obese) categories. Results: Sedentary time significantly increased, and all physical activity volumes significantly decreased among all participants. Although most variables did not change significantly in the 40-49 and 50-59 year age categories, similar changes as all participants were observed across all other categories. In the correlation analyses, changes in sedentary time correlated, at most, only modestly for each change in physical activity volumes, indicating that increased physical activity volume does not always lead to decreased sedentary time, and vice versa. Conclusions: Strategies to reduce sedentary time and promote physical activity are needed in Japan, particularly for people aged >= 60 years.