Sitting time and cardiometabolic risk in US adults: associations by sex, race, socioeconomic status and activity level

Background: Sitting time is associated with adverse health outcomes including chronic disease and premature mortality. However, it is not known if the association of sitting time with cardiometabolic risk factors varies across sociodemographic or health factors. Methods: The sample included 4560 adults (≥20 years) who participated in the cross-sectional 2007-2010 US National Health and Nutrition Examination Survey. Participants self-reported typical daily sitting time. Weight, height, blood pressure, and fasting triglycerides, high-density lipoprotein-cholesterol (HDL-C), glucose and insulin were measured. Homeostatic model assessment-insulin resistance (HOMA-IR) and β cell function (HOMA-%B) were calculated. A subsample of 3727 participants underwent an oral glucose tolerance test to obtain 2 h postload glucose levels. Population-weighted linear regression analysis was used to examine the association between sitting time and each cardiometabolic risk factor, stratified by sex, race, socioeconomic status and activity level. Analyses were controlled for demographics, socioeconomic status, survey cycle, personal and family medical history, diet and physical activity. Results: Sitting time was significantly associated with adverse levels of waist circumference, body mass index, triglycerides, HDL-C, insulin, HOMA-IR, HOMA-%B and 2 h postload glucose, but not with blood pressure or glucose level. In stratified analyses, sitting time was most consistently related to cardiometabolic risk factors among low and middle socioeconomic groups and for those who reported no weekly physical activity, but there were few differences between sex or race groups. Conclusions: Self-reported sitting time was associated with adverse cardiometabolic risk factors consistently across sex and race groups in a representative US sample, independent of other risk factors. Excessive sitting warrants a public health concern.