Sedentary Behavior and Obesity in Youth According to Meeting Physical Activity Guidelines: National Health and Nutrition Examination Survey 2003-2006.

The purpose of this study was to examine the association between sedentary time and obesity in youth according to meeting physical activity guidelines. A total of 1991 youth (10-17 years) from the 2003 to 2006 National Health and Nutrition Examination Survey were included in the analysis. Physical activity was categorized into two levels: (1) daily engagement in ≥60 minutes of moderate and vigorous physical activity (MVPA) and (2) <60 minutes per day of MVPA. Sedentary time was categorized into four levels using quartiles. BMI was categorized into two levels using sex-specific BMI for age percentiles from the CDC: (1) obese group: BMI ≥90 percentile and (2) nonobese group: BMI <90 percentile. After adjusting for covariates, among those meeting physical activity guidelines, there was a statistically significant relationship between sedentary time and obesity for Q1 (sedentary time <383.5 min/day) vs. Q4 (sedentary time >523.5 min/day) [odds ratio (OR) = 0.14, 95% confidence interval (CI): 0.02-0.87] and Q2 (sedentary time = 383.5-451.83 min/day) vs. Q4 (sedentary time >523.5 min/day) (OR = 0.16, 95% CI: 0.03-0.99). Among youth not meeting physical activity guidelines, however, sedentary time was not associated with obesity [OR = 0.72 (Q1 vs. Q4), OR = 0.88 (Q2 vs. Q4), OR = 1.08 (Q3 vs. Q4)]. These results indicate that sedentary time is associated with obesity among those meeting physical activity guidelines. However, the relationship between sedentary time and obesity in a low physical activity group is not obvious. Therefore, to confirm the role of low-level physical activity on the relationship between sedentary time and health outcomes, further investigation is required.