Temporal trends and recent correlates in sedentary behaviours in Chinese children

Background: Sedentary behaviours (television, video and computer) are related to health outcomes independent of physical activity. Few studies have examined trends and correlates of sedentary behaviours among youth in developing nations. The current study is to examine temporal trends in sedentary behaviours and recent correlates of screen use in Chinese children during a period of economic transition. Methods: Secondary analysis of China Health and Nutrition Surveys. Cross-sectional data on sedentary behaviours including screen use among children aged 6-18 years from four surveys in 1997 (n = 2,469), 2000 (n = 1,838), 2004 (n = 1,382) and 2006 (n = 1,128). Temporal trends in screen use by socio-demographic characteristics were examined. The correlates of spending more than 2 hours per day on screen time in the most recent survey data (2006, n = 986) were analysed using survey logistic regression analysis. Results: Daily screen time significantly increased in each subgroup by age, sex and urban/rural residence, with the largest increase for urban boys aged 13-18 years from 0.5 hours to 1.7 hours, and for rural boys aged 6-12 years from 0.7 hours to 1.7 hours (p < 0.0001). Daily time in both homework and extracurricular cultural activity increased significantly from 2000 to 2004 but was stable from 2004 to 2006. Boys (OR: 1.41, 95%CI: 1.09 - 1.82), having a TV in the bedroom (OR: 1.86, 95%CI: 1.15 - 3.01), having access to internet at home (OR: 1.93, 95%CI: 1.12 - 3.31) or at internet cafes (OR: 2.01, 95%CI: 1.21 - 3.34), or often watching TV with parents (OR: 2.27, 95%CI: 1.37 - 3.74) were all associated with being more likely to be high screen users (>= 2 hours/day). While children aged 13-18 years (OR: 0.67, 95%CI: 0.46-0.97) were less likely to be high screen users. Children whose parents often have rules on their TV viewing (OR: 0.64, 95%CI: 0.37 - 1.10) were slightly but not significantly less likely to be high screen users. Conclusion: This study confirms sedentary behaviour has increased over the last decade in Chinese children. Efforts to ensure Chinese youth meet screen time guidelines include limiting access to screen technologies and encouraging parents to monitor their own screen time and to set limits on their child's screen time.