Objective: To explore the correlation between obesity and first ejaculation in boys aged 11-18 years old in Ningxia in 2019, and to provide the theoretical reference for puberty development among obese boys. Methods: Using the method of stratified random cluster sampling, 5 240 boys aged 11- 18 were selected from Yinchuan, Zhongwei, Wuzhong and Guyuan in Ningxia Hui Autonomous Region. Height, weight, and first ejaculation were obtained.Body mass index (BMI) was calculated to determine nutritional status, and the χ 2 test was used to compare the differences between groups of nutritional status; the probability unit regression method was used to calculater the soth percentile age at ejaculation, and the U test was applied to compare the differences in age at ejaculation between groups. Results: The rates of overweight and obesity among boys aged 11 to 18 years in Ningxia Hui Autonomous Region in 2019 were 15.5% and 8.8%. The detection rate of overweight and obesity among urban boys was 17.8% and 10.5% and the detection rate of overweight and obesity among rural boys was 12.9% and 6.9%,respectively. The 50 th percentile age at half ejaculation among urban boys aged 11 to 18 years was 14.94 years; the 50 th percentile age at ejaculation among rural boys was 15.33 years( P <0.01). The 50 th percentile age at ejaculation was 15.61, 15.10, 15.05 and 15.05 years for boys in the wasted, normal weight, overweight and obese groups, respectively. Conclusion Nutritional status was not associated with age at first ejaculation in the present study,but warrants farther investigation.

Objective: To understand the nutritional status and physical quality of children and adolescents aged 6-18 in Ningxia in 2019, so as to provide scientific basis for health promotion children and adolescents. Methods: A total of 16 076 children and adolescents aged 6-18 years old from Ningxia were selected by multi stage stratified cluster random sampling. Weight, height and physical fitness indexes (50 m running, standing long jump, sitting forward flexion) were measured and analyzed. The Chi square test was carried out to compare differences between groups, and the relationship between nutritional status and physical fitness was assessed by Logistic regression models. Results: In 2019, detection rate of stunting loss rate, overweight and obesity rate of children and adolescents aged 6-18 in Ningxia were 6.9%, 12.6% and 8.7%, respectively. The below average rates of sitting forward flexion, 50 m running and standing long jump were 10.0%, 8.6% and 26.7%, respectively, while the passing rates were 63.5%, 63.7% and 55.5%, respectively. The good rates were 14.7%, 11.7% and 12.3%, and the excellent rates were 11.8%, 16.0 % and 5.5%, respectively. The passing rates of sitting forward flexion, 50 m running and standing long jump in stunting group were lower than those in the normal weight group ( OR=0.75, 0.72, 0.77, P ＜0.05); the passing rates of 50 m run and standing long jump in the overweight group was lower than that of normal weight group ( OR=0.79, 0.52, P ＜0.05); the passing rates of sitting forward flexion, 50 m running and standing long jump in the obese group were lower than those in the normal weight group ( OR=0.73, 0.52, 0.32, P ＜0.05). Conclusion In 2019, children and adolescents in Ningxia have the doublel burden of stunting, overweight and obesity. Physical fitness is associated with nutritional status, suggesting weight control might be helpful to keep fitness among children and adolescents.

Objective: To investigate the trend of overweight and obesity among Han students aged 7-18 in Ningxia from the year of 2000 to 2019, and to provide scientific basis for obesity prevention and control among children and adolescents. Methods: Based on the five waves of "National Student Physical Fitness and Health Survey" in Ningxia region during 2000 to 2019, body weight, height, waist circumference, hip circumference and other data of Han students aged 7-18 years were included was used for trend analysis. Results: In 2019, the detection rates of overweight and obesity in children and adolescents aged 7 to 18 in Ningxia were 13.34% (1 181/8 855) and 9.19% (814/8 855), respectively. The increase rate of overweight and obesity in boys from 2000 to 2019 was 11.68% and 10.07% ( χ 2=27.60, P <0.01). The rate of overweight and obesity in female students from 2000 to 2019 was 6.95% and 5.77% ( χ 2=33.82, P <0.01). Urban boys had the highest rates of overweight and obesity, which were 11.38% and 10.45%. The growth rate of overweight and obesity in rural boys was higher than that in urban boys after 2010 ( χ 2=13.90,17.09, P < 0.05), and the growth rate of obesity in rural girls was higher than that in urban girls after 2014 ( χ 2=9.94, 33.39, P <0.05). Overweight and obesity prevalence showed positive associations with the economic status in both urban and rural areas ( χ 2=35.19, 35.35, P <0.01). Conclusion From 2000 to 2019, the prevalence of overweight and obesity and body mass index among children and adolescents in Ningxia increased consistently, with more rigirous in rural areas. Specific strategies and measures for overweight and obesity prevention in children and adolescents are in urgent need, to reduce potential social and economic burden.

Objective: To understand the influencing factors underlying physical exercise behavior among children and adolescents aged 9-18 years in Ningxia, China, in 2019, and to provide suggestions for physical exercise among children and adolescents by adopting a social ecological model. Methods: Based on data related to 12 018 children and adolescents in Ningxia aged 9-18 years old which were obtained from the National Survey on Students Constitution and Health in 2019, the survey questions scored based on the four levels of the social ecological model. Results: The proportion of children and adolescents who engaged in physical exercise for less than 1 hour a day accounted for 55.97% of the total number of people in Ningxia. Regardless of whether they were able to engage in enough physical activity, individual factors played a dominant role in influencing the behavior of the children and adolescents, and an interaction was found between influencing factors at different levels( r=-0.01, 0.01, -0.08, 0.04, P <0.01). The results of the stepwise regression analysis showed that the personal factors e.g. sports makes me healthy, I don t have enough time, muscle strength exercise, I have no movement of any relationship partner, sports make me know partner, policy in the number of physical education, number of sports meeting in a school year, the average daily lesson hold number all affect children s sports activities in time( B =-0.05-0.16, P <0.01). Conclusions The lack of physical exercise among children and adolescents in Ningxia is the result of multiple factors. Comprehensive and diversified intervention should be administered from a socio ecological framework to promote the formation of physical exercise habits among children and adolescents.