Associations of sedentary behavior bouts with community-dwelling older adults' physical function

The study aim was to explore associations between sedentary behavior (SB) bouts and physical function in 1360 community-dwelling older adults (≥65 years old). SB was measured using an ActiGraph wGT3X + accelerometer for seven consecutive days at the dominant hip and processed accordingly. Various SB bout lengths were assessed including: 1- to 9-minutes; 10- to 29-minutes; 30- to 59-minutes; and ≥60-minutes, as well as maximum time spent in a SB bout. Total SB time was adjusted for within the SB bout variables used (percentage SB time in the SB bout length and number of SB bouts per total SB hour). Physical function was assessed using the 2-minute walk test (2MWT), 5-times sit-to-stand (chair stand) test, and unipedal stance test (UST). Hierarchical linear regression models were utilized. Covariates such as moderate-vigorous physical activity (MVPA), demographic and health characteristics were controlled for. Lower percentage time spent in ≥60-minute SB bouts was significantly (P <.05) associated with longer 2MWT distance while lower numbers of ≥60-minute SB bouts were associated with longer 2MWT distance, shorter chair stand time and longer UST time. There were mixed associations with physical function for 10- to 29-minute SB bouts. In a large cohort of European older adults, prolonged SB bouts lasting ≥60-minutes appear to be associated with reduced physical function after controlling for MVPA and numerous other important covariates. Besides reducing SB levels, these findings suggest there is a need to regularly interrupt prolonged SB to improve physical function in older adults.