Associations of older adults' physical activity and bout-specific sedentary time with frailty status: compositional analyses from the NEIGE study

Aim: To examine associations of intensity-specific physical activity and bout-specific sedentary time with frailty status among Japanese community-dwelling older adults, taking into account the interrelationships of these behaviors. Methods: Participants were 511 community-dwelling older adults. Physical activity and sedentary time were assessed using a tri-axial accelerometer. Frailty status (frail, pre-frail, or robust) was determined, based on the phenotypic model and used established criteria for Japanese older adults. Associations with frailty status of intensity-specific physical activity and bout-specific sedentary behavior (SB) time were examined using compositional data analysis, adjusted for potential confounders. Results: Participants included 13 (2.6%) who were frail, 234 (45.8%) pre-frail, and 264 (51.6%) who were robust. For the frail and pre-frail, the proportion of time spent in moderate-to-vigorous physical activity (MVPA) was less than for those who were robust. Frail older adults has larger proportion of time spent in prolonged (≥30 min/bouts) sedentary behavior (SB), and less in short-bout (<30 min/bout) SB, compared to the robust. No statistically-significant differences in the proportion of time spent in light-intensity physical activity was found across frailty levels. Conclusion: Pre-frail and frail older adults spend proportionally less time in MVPA and more time in prolonged SB, compared with those who were robust. These findings need to be confirmed by evidence from larger and more-diverse study samples and by evidence from prospective studies, in order to better understand whether or not avoiding prolonged periods of sitting could be a potential strategy for preventing frailty among community-dwelling older adults.