• Huaidong Du, Derrick Bennett, Liming Li, Gary Whitlock, Yu Guo, Rory Collins, Junshi Chen, Zheng Bian, Lai-San Hong, Shixian Feng, Xiaofang Chen, Lingli Chen, Renxian Zhou, Enke Mao, Richard Peto, Zhengming Chen, and China Kadoorie Biobank Collaborative Group.
• Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK. huaidong.du@ctsu.ox.ac.uk
• Am. J. Clin. Nutr. 2013 Mar 1;97(3):487-96.

BackgroundFew large studies in China have investigated total physical activity and sedentary leisure time and their associations with adiposity.ObjectiveWe investigated determinants of physical activity and sedentary leisure time and their associations with adiposity in China.DesignA total of 466,605 generally healthy participants (age: 30-79 y, 60% female) in the China Kadoorie Biobank were included in this cross-sectional analysis. Self-reported information on a range of activities was collected by interviewer-administered questionnaire. Physical activity was calculated as metabolic equivalent task hours per day (MET-h/d) spent on work, transportation, housework, and nonsedentary recreation. Sedentary leisure time was quantified as hours per day. Adiposity measures included BMI, waist circumference, and percentage body fat (by bioimpedance analysis). Associations were estimated by linear and logistic regression.ResultsThe mean physical activity was 22 MET-h/d, and the mean sedentary leisure time was 3.0 h/d. For each sex, physical activity was about one-third lower among professionals/administrators than among factory workers, with intermediate levels for other occupational categories. A 1-SD (14 MET-h/d) greater physical activity was associated with a 0.15-unit (95% CI: 0.14, 0.16) lower BMI (in kg/m(2)), a 0.58-cm (95% CI: 0.55, 0.61) smaller waist circumference, and 0.48 (95% CI: 0.45, 0.50) percentage points less body fat. In contrast, a 1-SD (1.5 h/d) greater sedentary leisure time was associated with a 0.19-unit higher BMI (95% CI: 0.18, 0.20), a 0.57-cm larger waist circumference (95% CI: 0.54, 0.59), and 0.44 (95% CI: 0.42, 0.46) percentage points more body fat. For any given physical activity level, greater sedentary leisure time was associated with a greater prevalence of increased BMI, as was lower physical activity for any given sedentary leisure time.ConclusionsIn adult Chinese, physical activity varies substantially by occupation, and lack of physical activity and excess sedentary leisure time are independently and jointly associated with greater adiposity.

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