The association between sedentary behaviour, moderate-vigorous physical activity and frailty in NHANES cohorts

Objectives: (1) To examine how sedentary behaviour and moderate-vigorous (MVPA) are each experienced during the day across different levels of frailty; (2) estimate and compare the extent to which high levels of sedentary behaviour and low levels of MVPA are associated with increased frailty and self-reported health, disability and healthcare utilization.

Methods: Community dwelling adults aged 50+ from the National Health and Nutrition Examination Survey (2003-2004; 2005-2006). Frailty was measured with the frailty index and physical activity was measured using ActiGraph accelerometers.

Results: On average, people engaged in about 8.5h of sedentary behaviour each day. The most frail individuals were more sedentary and less likely to meet weekly MVPA guidelines (9.57 h/day; 8.3%) than non-frail individuals (8.18 h/day; 1.1%; p<0.001). Frail individuals failed to demonstrate the patterns of the healthier individuals-higher levels of sedentary behaviour on Sundays and in the evenings and decreasing MVPA throughout the week. High sedentary behaviour and low MVPA were independently associated with higher levels of frailty, poor self-reported health, high ADL disability and higher healthcare usage.

Conclusions: Many people over the age of 50, and most of those who are frail, were highly sedentary with very few meeting the recommended weekly levels of MVPA. Sedentary behaviour and MVPA were independently associated with frailty and adverse health outcomes in middle to older aged adults. Future research should focus on a longitudinal study to determine the temporal relationship between sedentary behaviour and frailty.