The descriptive epidemiology of sitting among US adults, NHANES 2009/2010

Objectives: Using NHANES 2009/2010, to describe the amount of time a representative sample of the U.S. population spends sitting by age, sex, ethnicity, education, and body mass index.

Design: Cross-sectional analysis.

Methods: Participants (n=5911, ≥20 years) self-reported demographic variables and the amount of time they spend sitting on a typical day. Body mass index was calculated from measured height and weight.

Results: Mean self-reported sitting time was 285min/day for males and 281min/day for females. Mexican-Americans reported sitting less than both non-Hispanic Whites and non-Hispanic Blacks (all p<0.0001). Non-Hispanic White males reported sitting more than non-Hispanic Black males, while Non-Hispanic White females reported sitting more than Other Hispanic females (both p<0.0001). No significant differences were found between sexes in any age group. There was a trend for increased sitting time with increasing age for females (p for trend=0.0045), for all Mexican-American and Hispanic participants and non-Hispanic Black males (all p≤0.006) and with increasing education (p for trend <0.0001). At the College Graduate level, females reported sitting less than males (p<0.0001). Obese females reported sitting more than normal weight and overweight females (p=0.0008). There were no significant differences in sitting time by body mass index for males.

Conclusions: Self-reported sitting time differed by ethnicity, age group, education and body mass index but there was no overall difference by sex. These results represent the most up to date prevalence of self-reported sitting for the US adult population. Certain groups should be targeted to reduce sitting time, for example those with higher educational attainment and obese females.