Objective: To evaluate the effects of physical activity interventions based on social ecology model, and to explore promising approach for increasing physical activity of students in large cities. Methods: A quasi-experimental design with parallel control was implemented. Students from grade 4 in 20 primary schools in 3 districts of Shanghai were recruited. Based on social ecology model, physical activity interventions were carried out in three levels: personal, social-and physical environment. The interventions lasted for 6 months. Questionnaires, physical examinations and physical fitness tests were carried out. Rank sum test, chi-square test and logistic stepwise regression was used to analyze the intervention effects. Results: In the intervention group, the proportion of students who favored physical activity increased from 47.9% to 50.7%. Time spent in moderate to vigorous intensity physical activity (MVPA) increased from 64 min/d to 70 min/d, mainly during the weekend. The interventions showed significant effects, especially for girls. In the intervention group, the proportion of students spent 1 h/d in MVPA increased from 53.7% to 57.7%(χ2=4.95, P<0.05). Multivariate analysis showed that after intervention, the proportion of students spent more than 1 h/d in MVPA in the intervention group was higher than that in the control group (OR=1.22, 95%CI=1.02-1.48, P=0.03). Conclusion Physical activity interventions based on social ecology model can increase uptake of physical activity among school students.

Objective: To investigate the relationship between body fat percentage (BF%) and high blood pressure among adolescents in Shanghai, and to provide basis for early prevention and intervention of cardcovascular diseases. Methods: By using stratified cluster sampling method, a total of 5 148 adolescent students in 16 schools from 16 districts of Shanghai were selected. Questionnaire survey and physical examination were performed. The bioelectrical impedance analysis (BIA) was used to measure body fat percentage. National Blood Pressure Reference for Chinese Han Children was used to define high blood pressure. And T test, chi-square test and Logistici regression were used to assess the relation between BF% with high blood pressure. Results: The prevalence of high blood pressure in 5 148 junior middle school students in Shanghai was 10.98%, with girls (13.13%) higher than boys (8.99%)(χ 2=22.48, P<0.01). The average total body fat percentage of male students was (20.90±10.73)%, which decreased with age (linear trend variance is 10.04, P<0.01). The average total body fat percentage of girls was (25.14±8.03)%, which increased with age (linear trend variance is 69.23, P<0.01). After adjusted for age, diet, exercise and other influencing factors, the prevalence of hypertension showed an increasing trend with the increase of body fat percentage for both boys and girls. The risk of high blood pressure in boys with BF%≥P 90 was 12.43 times higher than that in boys with BF%

Conclusion There was a positive correlation between body fat percentage and high blood pressure in adolescents. The prevalence of high blood pressure increased with the increase of body fat percentage, which was more obvious in boys.

Objective: To explore the relationship between myopia and nutritional status among upper elementary students in Shanghai. Methods: A stratified cluster sampling method was used to select 5 576 fourth and fifth grade students from 16 districts in Shanghai, vision test, physical examination and questionnaire survey were administered. Two level multivariate Logistic regression and mixed linear models were used to analyze the relationship between myopia, spherical equivalent (SE) and nutritional status. Results: The detection rates of overweight and obesity were 17.0%(949) and 18.7%(1 042), respectively. There was a statistical difference in the proportion of the nutritional status in boys and girls( χ 2=210.94, P <0.01), with overweight and obesity in boys higher than those of girls. The overweight boys were more likely to have myopia (univariate analysis: OR=1.23, P =0.04; multivariate analysis: OR=1.21, P =0.06) than the normal weight boy. Overweight students tended to had more negative refractive than those with normal weight in both boys and girls(multivariate analysis, boys: β =-0.19, girls: β=-0.24, P <0.05). Myopia risk and refractive power in obese students showed no statistical difference with normal weight students( P >0.05). Conclusion Overweight students have lower SE than the normal weight among upper elementary students of Shanghai, more researches are needed to confirm this finding and to provide theoretical bases for myopia prevention and control.