Accelerometer-measured sedentary and physical activity time and their correlates in European older adults: the SITLESS study

Background: Sedentary behavior (SB) and physical activity (PA) are important determinants of health in older adults. This study aimed to describe the composition of accelerometer-measured SB and PA in older adults, to explore self-reported context-specific SB, and to assess socio-demographic and functional correlates of engaging in higher levels of SB in participants of a multi-center study including four European countries. Methods: 1360 community-dwelling older adults from the SITLESS study (61.8% women; 75.3±6.3 years) completed a self-reported SB questionnaire and wore an ActiGraph accelerometer for seven days. Accelerometer-determined compositional descriptive statistics were calculated. A fixed effects regression analysis was conducted to assess the socio-demographic (country, age, sex, civil status, education and medications) and functional (BMI and gait speed) correlates. Results: Older adults spent 78.8% of waking time in SB, 18.6% in light-intensity PA (LPA), and 2.6% in moderate to vigorous PA (MVPA). Accelerometry showed that women engaged in more LPA and walking and men engaged in higher amounts of MVPA. Watching television and reading accounted for 47.2% of waking time. Older age, being a man, single, taking more medications, being obese and overweight, and having a slower gait speed were statistically significant correlates of more sedentary time. Conclusions: The high amount of SB of our participants justifies the need to develop and evaluate interventions to reduce sitting time. A clinically relevant change in gait speed can decrease almost 0.45 percentage points of sedentary time. The distribution of context-specific sedentary activities by country and sex showed minor differences, albeit worth noting.