| BackgroundAt present, childhood obesity in the world is at an alarming rate. China has twelve million overweight and obese children and adolescents. Child overweight and obesity will lead to many health problems, such as heart disease, diabetes, fatty liver, gallbladder disease, hypertension, sleep apnea syndrome, mental diseases and so on. About 70% of the adolescent obese children remain obese as adults.The lifestyle behaviors including eating behavior are mostly formed in the period of childhood. Once formed, it will be difficult to change, so the period of children and adolescents is the critical period to prevent overweight and obesity. School children spent most of time in school, and school-based physical activity intervention program is easy to organize and implement. Physical activity can promote the health of school children, reduce and control the incidence of overweight and obesity.ObjectivesThe main purpose of the study is to analyze the effect and sustainability of school-based physical activity in physique, body composition, physical fitness, the rate of overweight and obesity, and blood-lipid. Second, to expore the factors that influence the effect of intervention. Third, to find the focus groups in the physical activity intervention, and develop the appropriate intervention strategies. Finally, provide scientific basis and data support for the development of nationwide school-based obesity prevention programs.Subjects and methodsThe design was randomized, controlled intervention trial. A total of 4753 children grade 3-4 were recruited with cluster sampling method from 20 primary schools in Chongwen District and Dongcheng District of Beijing. All the students were divided into 2 groups:2350 students in the intervention group with "Happy 10" twice a school day, and 2403 students in the control group without any interventions. Intervention lasted 1 year followed by a followe-up in the subsequent year. The information on height, weight, lean body mass, body fat, skinfold thickness, forced vital capacity and grip was collected by trained investigators in the morning of study day. General condition, dietary intake and physical activity investigation were collected using validated questionnaires by trained investigators. Measured blood lipids of the voluntarily participated students. It's including triglycerides, total cholesterol, high density lipoprotein cholesterol. t test, chi-square test to compare the different between groups. And mixed model and generalized model were used to exam the effect of intervention influencing factors.Results1. Physical activity intervention on physique and influence factorsIn the intervention period, the gain data of intervention group and control group students was as following:6.0cm and 6.3cm for height,4.2kg and 4.8kg for weight, 0.5kg/m2 and 0.7kg/m2 for BMI. The gain of height, weight and BMI of students among intervention group lower than that of control group (P<0.01). In the follow-up period, the gain data of intervention group and control group students was as following:12.1cm and 12.0cm for height,9.9kg and 10.2kg for weight,1.6kg/m2 and 1.7kg/m2 for BMI.The influence factors of physical activity intervention included sex, age, mother education, weight status and energy intake situation. In the intervention period, the gain of height of students with 8-9 years old, middle education mother, normal weight or obese among intervention group significantly lower than that of control group; the gain of weight of students with 9-10 years old, high education mother, normal weight or dietary intake reduced or unchanged among intervention group significantly lower than that of control group; the gain of BMI of students with 9 years old or normal weight among intervention group significantly lower than that of control group. The gain of height and weight of students with low education mother among intervention group significantly lower than that of control group in the intervention period and follow-up period. It was similar to the gain of weight and BMI of students with normal weight and the gain of BMI of girls.2. Physical activity intervention on body composition and influence factors2.1 Body fatIn the intervention period, the gain data of intervention group and control group students was as following:4.0kg and 4.4kg for lean body mass,0.3kg and 0.5kg for body fat,-2.1% and -2.0% for body fat percentage. The gain of lean body mass and body fat of students among intervention group lower than that of control group (P< 0.05). In the follow-up period, the gain data of intervention group and control group students was as following:7.7kg and 7.6kg for lean body mass,2.3kg and 2.6kg for body fat,-0.4% and 0.1% for body fat percentage. There were significant differences in changes in body fat and body fat percentage in the intervention group versus the control group(P<0.05).The influence factors of physical activity intervention included sex, age, mother education, weight status, and energy intake situation. In the intervention period, the gain of lean body mass of students with 8-10 years old, middle & high education mother, normal weight or obese among intervention group significantly lower than that of control group; the gain of body fat of students with 9 years old or high education mother among intervention group significantly lower than that of control group. In the follow-up period, the gain of body fat of students with 10 years old or obese among intervention group significantly lower than that of control group; the reduce of body fat percentage of students with female, middle & high education mother or normal weight among intervention group significantly higher than that of control group. The gain of lean body mass of students with low education mother among intervention group significantly lower than that of control group in the intervention period and follow-up period. It was similar to the gain of body fat of students with female.2.2 Skinfold thicknessIn the intervention period, the gain data of intervention group and control group students was as following:3.1mm and 3.0mm for triceps skinfold thickness,1.8mm and 2.2mm for subscapular skinfold thickness. In the follow-up period, the gain data of intervention group and control group students was as following:1.2mm and 0.7mm for triceps skinfold thickness,0.6mm and 0.2mm for subscapular skinfold thickness. The gain of triceps skinfold thickness of students among intervention group higher than that of control group (P<0.01).The influence factors of physical activity intervention included sex, age, mother education, and weight status. In the intervention period, the gain of subscapular skinfold thickness of students with male or 9 years old among intervention group significantly lower than that of control group. In the follow-up period, the gain of triceps skinfold thickness of students with male,8 years old, middle education mother, normal weight, obese among intervention group significantly higher than that of control group.3. Physical activity intervention on physical fitness and influence factorsIn the intervention period, the gain data of intervention group and control group students was as following:314.2ml 322.9ml for forced vital capacity,0.3kg and 0.7kg for grip. The reduce of grip of students among intervention group lower than that of control group (P<0.05). In the follow-up period, the gain data of intervention group and control group students was as following:391.4ml 387.4ml for forced vital capacity,0.2kg and 0.4kg for grip.The influence factors of physical activity intervention included sex, age, income, mother education and weight status. In the intervention period, the gain of grip of students with female or middle income among intervention group significantly higher than that of control group; the reduce of grip of students with 8-9 years old or normal weight among intervention group significantly lower than that of control group. In the follow-up period, the gain of forced vital capacity of 10 years old students among intervention group significantly higher than that of control group; the gain of grip of boys among intervention group significantly lower than that of control group; the reduce of grip of low income among intervention group significantly higher than that of control group.4. Physical activity intervention on the incidence of overweight and obesity and influence factorsIn the intervention period, the gain data of intervention group and control group students was as following:1.0% and 1.5% for overweight rate,0.9% and 0.8% for obesity rate. In the follow-up period, it was 2.6% and 2.7%,0.8% and 0.1%, respectively. Whether intervention or follow-up period, the gain of overweight rate among intervention group significantly lower than that of control group, and the reduce of obesity rate higher than that of control group, but there were not significant differences in changes between the intervention group and the control group(P> 0.05). The influence factors of physical activity interven tion included sex, and weight status, but there were not significant differences in changes between the intervention group and the control group of every group(P>0.05).5. Physical activity intervention on blood-lipids and influence factorsIn the intervention period, the gain data of intervention group and control group students was as following:0.1mol/l and 0.0mol/l for TG,0.2mol/l and 0.0mol/l for TC,0.6mol/l and 0.5 mol/l for HDL-C. The gain of TC and HDL-C of students among intervention group higher than that of control group (P<0.01). In the follow-up period, the gain data of intervention group and control group students was as following:0.6mol/l and 0.9mol/l for TG,0.2mol/l and 0.1mol/l for TC,0.6mol/l and 0.5 mol/l for HDL-C. The gain of TC of students among intervention group lower than that of control group (P<0.01), and the gain of TG and HDL-C higher than that of control group (P<0.05).The influence factors of physical activity intervention included sex, income, mother education, and weight status. In the intervention period, the gain of TC of normal weight students among intervention group significantly higher than that of control group; the gain of HDL-C of students with middle income or obese among intervention group significantly higher than that of control group. In the f ollow-up period, the gain of TG of normal weight students among intervention group significantly lower than that of control group. The gain of TC of normal weight students among intervention group significantly lower than that of control group in the intervention period and follow-up period. It was similar to the gain of HDL-C of students with female, middle income, middle education mother or normal weight.Conclusions1. School-based physical activity interventions can decrease the gain of BMI, body fat, body fat percentage, triglycercide and the reduce of grip of primary school students.2. School-based physical activity intervention can increase the gain of forced vital capacity and high density lipoprotein cholesterol of primary school students.3. School-based physical activity interventions can control the development of overweight and obesity rate of primary school students.4. School-based physical activity interventions is effective on primary school students with female,9 years old, middle income, middle education mother, energy intake reduced or unchanged.
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