14. Sedentary time and cardio-metabolic biomarkers in US adults: NHANES 2003–06
Title: Sedentary time and cardio-metabolic biomarkers in US adults: NHANES 2003–06
Commentary by Rona Macniven, Cluster for Physical Activity and Health (CPAH), University of Sydney
Research evidence of the negative effects of too much sedentary behaviour is mounting, yet much currently remains unknown. This study, by Australian researchers, is one of the first to examine objectively measured sedentary time and breaks in sedentary time with continuous cardio-metabolic and inflammatory risk biomarkers such as C-reactive protein, finding adverse risks associated with prolonged sedentary time.
Data from 4,757 adults came from the 2003/04 and 2005/06 US National Health and Nutrition Examination Survey (NHANES), a cross-sectional, national representative study and accelerometers worn by participants. Analyses revealed relationships between sedentary time and unhealthy levels of cardio-metabolic indicators of HDL-cholesterol, C-reactive protein, triglycerides, insulin, HOMA-%B, and HOMA-%S and waist circumference. Breaks in sedentary time were associated with a healthier waist circumference and levels of C-reactive protein. Differences across age, sex and race/ethnicity were also explored but findings were fairly consistent across groups with the exception of females being more sedentary but taking more breaks and having healthier lipid profiles and race/ethnicity differences in the links between sedentary time and waist circumference (healthier associations for non-Hispanic blacks, no difference in Mexican Americans, unhealthy associations in non-Hispanic whites).
This study adds considerable good-quality evidence to the field of sedentary behavior in being one of the first to investigate C-reactive protein and to examine the effects of breaks in sitting time and these findings are enhanced by drawing on a large, representative sample. The findings call for specific public health messages to reduce sedentary behavior and the importance of regular breaks in sitting. Implications of these findings in every-day life, particularly in the workplace setting, require particular concern and calls to action.