Physical activity and sedentary leisure time and their associations with BMI, waist circumference, and percentage body fat in 0.5 million adults: the China Kadoorie Biobank study.
BACKGROUND
Few large studies in China have investigated total physical activity and sedentary leisure time and their associations with adiposity.


OBJECTIVE
We investigated determinants of physical activity and sedentary leisure time and their associations with adiposity in China.


METHODS
A 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.


RESULTS
The 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.


CONCLUSIONS
In 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.
Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK. huaidong.du@ctsu.ox.ac.uk
Huaidong
H
Du
Derrick
D
Bennett
Liming
L
Li
Gary
G
Whitlock
Yu
Y
Guo
Rory
R
Collins
Junshi
J
Chen
Zheng
Z
Bian
Lai-San
LS
Hong
Shixian
S
Feng
Xiaofang
X
Chen
Lingli
L
Chen
Renxian
R
Zhou
Enke
E
Mao
Richard
R
Peto
Zhengming
Z
Chen
D000273:Adipose Tissue; D050154:Adiposity; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009765:Obesity / Q000453:epidemiology*; D015995:Prevalence; D057185:Sedentary Behavior; D057566:Self Report; D012737:Sex Factors; D012959:Socioeconomic Factors; D055105:Waist Circumference