X Y Wu, S M Tao, S C Zhang, Y K Zhang, K Huang, F B Tao
[Analysis on risk factors of screen time among Chinese primary and middle school students in 12 provinces]
Zhonghua yu fang yi xue za zhi [Chinese journal of preventive medicine]
review published prospective observational studies relationship physical activity sedentary behavior development overweight adiposity emphasis methodologic issuessample size population studied length followup assessment exposure physical activity inactivity sedentary behavior assessment outcome relative weight overweight body fatness adiposity statistical approach main findings extracted summarized key methodological issues highlightedin total 17 studies physical activity 15 studies inactivitysedentary behavior identified mutually exclusive 20 unique studies reviewed results mixed studies showing inverse association physical activity weight fatness outcomes andor direct association inactivitysedentary behavior weight fatness outcomes effects identified generally small magnitude imprecise measurement activity exposures likely weakens observed relationships studies used prepost design limited duration followup 2y studies longer frequent followup always use advantageous statistical approachon balance available evidence prospective observational studies suggests increased physical activity decreased sedentary behavior protective relative weight fatness gains childhood adolescence addition improved measurement methods longer frequent followup well truly longitudinal analysis methods would help establish important prevention intervention targets identify subgroups development periods interventions would likely effective