Isotemporal Substitution Analysis for Physical Activity,Sedentary Behaviour and BMI among Primary and Middle School Students in Shanghai
Objective:To explore the isotemporal substitution association between physical activity and sedentary behaviour and body mass index(BMI)among primary and middle school students in Shanghai.Methods:A sample of 486 primary and middle school students aged 6-16 years old were selected.Physical activity and sedentary behaviour were objectively measured by accelerometers.Height and weight were measured using standard measuring instruments.The single models,partition models,and isotemporal substitution models were used.Results:Substituting 5 min of sedentary behaviour or light physical activity(LPA)with moderate-to-vigor-ous physical activity(MVPA)were associated with a lower BMI of middle school students by 0.194 kg/m2 and 0.207 kg/m2,a lower BMI of normal weight students by 0.118 kg/m2 and 0.108 kg/m2,and a lower BMI of overw-eight/obesity students by 0.151 kg/m2 and 0.147 kg/m2,respectively.Substituting 5 min of sedentary behaviour with MVPA or LPA were associated with a lower BMI of primary school students by 0.167 kg/m2 and 0.035 kg/m2,respectively.Sedentary behaviour replaced MVPA among middle school students,normal weight students,and overweight/obesity students and it replaces LPA or MVPA among primary school students,which were significa-ntly increased their BMI.Other isotemporal substitution methods did not show a significant correlation with BMI.Conclusion:There are school stage and weight status differences in the relationship between activity beha-viour and BMI.Substituting sedentary behaviour or LPA with MVPA is beneficial to the prevention and control of obesity among middle school students,and the substitution of sedentary behavior with MVPA and LPA can effectively reduce the BMI of primary school students.Substituting sedentary behavior or LPA with MVPA was beneficial to the weight control of normal weight and overweight and obese students,but the weight loss effect of overweight and obese students was greater than that of normal weight students.The development of exercise guidelines and obesity intervention strategies should comprehensively consider the interaction of activity behavi-our and provide targeted time use suggestions for students with different school stages and weight statuses.
children and adolescentsphysical activitysedentary behaviourobesityisotemporal substitution model
万方数据
维普
