The independent and combined associations of physical activity and sedentary behavior with obesity in adults: NHANES 2003‐06

OBJECTIVE: To examine the combined influence of moderate-to-vigorous physical activity (MVPA) and sedentary behavior on obesity in US adults. DESIGN AND METHODS: Cross-sectional analyses were undertaken on a nationally representative sample of 5,083 adults from the April 2003 and June 2005 National Health and Nutrition Examination Survey. Self-reported TV time was divided into low, moderate, and high categories. Accelerometer-derived total sedentary and MVPA minutes divided into low, moderate, and high tertiles. The independent associations between MVPA, TV, and total sedentary time and obesity were examined using logistic regression. Participants were then cross tabulated into nine MVPA-sedentary behavior groups, and logistic regression was used to examine the combined influence of MVPA and sedentary behavior on the odds of being obese. RESULTS: MVPA was consistently inversely associated with obesity, regardless of sedentary behavior [odds ratio (OR) = 1.80-4.00]. There were inconsistent positive associations between TV time and risk of obesity in men, but not between total sedentary time and risk of obesity in either men or women. CONCLUSIONS: Obesity was more strongly related to MVPA than either TV time or total sedentary time in US adults. Small differences in daily MVPA (5-10 min) were associated with relatively large differences in risk of obesity.