Correlates of Objectively Measured Sedentary Time in U.S. Adults: NHANES 2005–2006

Background/Purpose: Empirical evidence suggests that sedentary behavior, independent of MVPA, may be a risk factor for chronic diseases. Matthews et al. (2008) found that Americans spend more than 50% of their waking time in objectively measured sedentary behavior. Accordingly, there is an need for information necessary to plan effective interventions to decrease sedentary time. With regard to cultural diversity in the US, research suggests that health promotion efforts must be culturally relevant to different ethnic groups. In sum, identifying the correlates of sedentary behavior by ethnicity is an important step to address the problem. Therefore, this study was purposed to test ethnicity-specific demographic, psychological, and behavioral factors that may be associated with sedentary behavior in the US adult population.

Method: The 2005-2006 NHANES data from the US population representative sample were used. After excluding non-eligible samples and those with missing data on the selected variables, a total of 1,162 adults (20+ yrs old; n_men=743, n_women=419; n_Hispanics=218, n_White=721, n_Black=223) were analyzed. Sedentary time and MVPA were derived from accelerometer-based physical activity monitor (Actigraph 7163) data. Sedentary time and MVPA were classified by activity counts of 100- and 2020+ during monitor-wearing time, respectively. All other potential correlates (sex, age, education, marital status, poverty-to-income ratio, Hispanics’ acculturation, depression, perceived health, sleeping disorder, alcohol drinking, and smoking) were measured by self-report questionnaires.

Analysis/Results: Ethnicity-specific multiple regression models were tested to identify significant correlates of sedentary time at the .05 significance level. In the Hispanics’ regression model, household size (r=88.00, p=.01; 2 persons vs. 1 person) was the only significant correlate of sedentary time holding other variables constant. In the non-Hispanic Whites’ model, sex (r=-18.65, p=.03; female vs. male), age(r=1.26, p=.003), household size (r=-33.19, p=.04), and MVPA (r=-1.54, p=.02) were significantly associated with sedentary time. Lastly, age(r=2.38, p=.03), education(r=84, p<.001; college or more vs. less than high school), perceived health (r=-59.49, p=.02; very good vs. poor), and smoking (r=-42.52, p=.01; not at all vs. everyday) were significant predictors of non-Hispanic Blacks’ sedentary time.

Conclusions: Correlates of sedentary time were different by ethnic groups. Hispanics living with others spent more sedentary time compared to those living alone. Younger and male Whites who lived alone and did less MVPA were more sedentary than older and female counterparts living alone and doing more MVPA. Blacks spent more sedentary time if they were older and better-educated, rated their health poorer, and smoked more. This study provides supporting evidences that culturally relevant ethnic group-specific intervention is important to decrease sedentary time.