Physical inactivity is closely related to the continuous decline of physical fitness, the increasingly severe obesity, myopia and other health problems, which has become a global public health issue. Physical activity promotion of children and adolescents is a common concern in sports science and public health. However, health outcomeoriented physical activity promotion model has failed to achieve expected results. Based on the concept of physical literacy, components of physical literacy, and direct and indirect evidence, this paper expounds the relationship between physical literacy and physical activity promotion of children and adolescents, and reveals the implication of physical literacy to physical activity promotion of children and adolescents. It also points out that more empirical studies are needed in the future, including the development of physical literacy assessment tools for children and adolescents of different ages and physical conditions in China; more longitudinal studies on the relationship between physical literacy, physical activity participation and health; the direct effect of physical literacy intervention on physical activity behavior and health outcomes. Promotion of physical literacy is an important element for physical activity participation and physical fitness of children and adolescents, and to reduce the public health burden caused by physical inactivity.

Prevention and control of myopia in children and adolescents is a systematic project, which requires the government to lead and the whole society to make joint efforts. In order to steadily promote the prevention and control of myopia and popularize the appropriate technology of prevention and control of myopia, the National Health Commission of the People’s Republic of China issued and implemented the appropriate technical guidelines for prevention and control of myopia in children and adolescents (hereinafter referred to as the guidelines). This paper focuses on the background, significance and main contents of the guidelines, so as to improve the understanding of the guidelines by public health professionals and people concerned about the prevention and control of myopia in children and adolescents in China.

Objective: To explore the relationship between adolescents’ physical activity and motor skills, and to provide a new perspective for the promotion of adolescents physical activity. Methods: The subjects were 153 adolescents aged 12-14, including 73 boys and 80 girls were selected as participants. The accelerometer (ActiGraph GT3X+) was used to measuring physical activity of the subjects for 7 consecutive days. The Movement Assessment Battery for Children, Second Edition (MABC-2) was used to measure the level of development of motor skills. Results: The average time for subjects to participate in moderatetovigorous physical activity(MVPA) was 42.15 minutes per day, 15.7% of the subjects met the World Health Organization physical activity guidelines. 56% of subjects had an average level of motor development. There was a positive correlation between MVPA and the object control skill score(r=0.20, P<0.05). There was a positive correlation between low intensity physical activity and fine motor scores(r=0.23, P<0.01); There was a low correlation between moderatehigh intensity physical activity and object control in boys(r=0.29, P<0.05), and no correlation was found among girls. Conclusion Time spent in moderatetovigorous physical activity among adolescents is still insufficient. The mutual promotion of physical activity and motor skill provides a new perspective for developing the motor skills of children and adolescents to improve moderatetovigorous physical activity.

Objective: To provide baseline data for the development of physical activity and health promotion strategies and public health policy among Chinese children and adolescents by systematically evaluating accelerometermeasured moderatetovigorous physical activity (MVPA) and sedentary behavior(SB). Methods: The study search was carried out using China National Knowledge Infrastructure, SPORTDiscus with Full Text, and Web of Science, including studies that published from January 1, 2009 to February 28, 2019. The studies were selected by inclusion (based on PICOS principles) and exclusion criteria, and were assessed through quality assessment items based on revised STROBE statement. The information about MVPA and SB were extracted, and Comprehensive Metaanalysis Software (CMA V2) was used to pool the findings from the included studies into a Metaanalysis. Results: Sixteen studies published from 2012 to 2019 were included the Metaanalysis. Sample sizes of eligible studies ranged from 96 to 2 163 participants. Metaanalysis found that Chinese children and adolescents separately spent 37.66 min/day, 539.61 min/d in MVPA and SB. Boys were more likely to have higher level of MVPA in minutes compared to the girls’(P<0.01). Children and adolescents spent more time in MVPA on weekdays than weekends(P<0.05), and also spent more SB on weekdays than weekends(P<0.05). Conclusion Chinese children and adolescents are physically inactive and live a sedentary lifestyle in general, especially among girls. MVPA and SB time among children and adolescents spent on weekdays are higher than weekends.

Objective: To investigate the variability of the time and frequency of Moderate to Vigorous Physical Activity (MVPA) during the school days and weekends of junior high school students, and to explore the correlation between MVPA and physical fitness. Methods: A cluster sampling method was used to investigate 79 students of grade 1 and grade 2 in Beijing Huilongguan Middle School. Adapted one day physical activity recording tool was implemented to investigate students’ physical activity from 8:00 to 23:00 a week, activity records were classified into daily MVPA parts and non MVPA parts based on MET values. Physical activity time series for 5 consecutive days and 2 weekends, as well as MVPA total time and the lempel ziv complexity of the sequence was calculated. Investigated the correlation between the MVPA situation and the results of national students’ physical fitness standard test. Results: There was no statistical difference in MVPA time between males and females during school days( t =-0.90, P >0.05). Females had greater variability in MVPA than males(58.9%, 53.5%). There was also no statistical difference in MVPA complexity between genders( t =-0.55, P >0.05). During weekends, there was no significant difference in the total MVPA time between men and women( t =-0.13, P >0.05). The CV of male MVPA time was lower than that of female(141.5%, 152.8%). There was also no significant difference( t =-0.63, P >0.05), and male MVPA complex CV was slightly higher than that of female ( 55.1% , 48.1%). The MVPA time CV of adolescents during weekdays was slightly lower for males (weekdays vs weekends: 53.5%, 141.5%) than females(58.9%, 152.8%). The MVPA complexity in weekdays among males was moderately correlated with BMI( r =0.41), and the MVPA time and weight of females ( r =-0.30) and BMI ( r =-0.31) were low. The complexity was related to body weight ( r =-0.31) and BMI ( r =-0.33) to a low degree( P <0.05). Conclusion Junior middle school students are more active on school days than weekend, but the MVPA time series are limited. Schools can effectively improve physical fitness by spreading out the activity period of MVPA in one day. MVPA complexity, as a more comprehensive indicator, may be more sensitive to BMI of junior middle school students.

Objective: To understand the current situation of early childhood sexuality education among parents of leftbehind children in rural areas and associated factors, to provide the evidence to launch the sexuality education for left behind children in rural areas in the future. Methods: An anonymous questionnaire survey was conducted among 1 348 parents of left behind children in rural areas who were selected by multistage stratified sampling during Mar. to May. 2018. Results: The rate of early childhood sexuality education of rural areas in Sichuan was 48.4%(652). Multivariate analysis showed that parents whose child was in higher grade ( OR=1.32, 95% CI =1.12-1.55); total annual income <10 000 yuan( OR=1.48, 95%CI =1.02-2.14), children had asked sexrelated questions ( OR=1.44, 95%CI =1.11-1.87), reckoning it necessary( OR=3.78, 95%CI =2.57-5.58), considering children’s sexuality education should be held by parents ( OR=2.69, 95%CI =1.78-4.07), other family members had launched the early childhood sexuality education( OR=7.86, 95%CI =5.16-11.95), school had launched it ( OR=3.13, 95%CI =2.25-4.34) had a highter rate of early childhood sexuality education. Conclusion Early childhood sexuality education of parents of left behind children of rural areas in Sichuan is in low level. Sexual health education should be based in school, together with parental training towards positive attitude and increases in early childhood sexuality education.

Objective: To understand the results of tuberculin skin test (PPD) in preschool children after the vaccination of BCG, and to analyze the effect of BCG vaccination on latent tuberculosis infection in children. Methods: From January to November 2018, a total of 1 359 preschool children from 14 kindergartens in 8 districts and cities of Jiangsu Province were selected for tuberculin test(PPD), and chest X-ray examination was performed on children with strong PPD results. Results: The positive rate of PPD in preschool children in Jiangsu Province was 23.33%, of which strong positive and moderate positive (PPD≥10 mm) were totaled 6.47%. There were 149 boys (21.29%) with PPD positive reactions and 168 girls(25.50%) with PPD positive reactions, and differences of PPD positive reactions with different genders were of no statistical significance (χ2=3.36, P>0.05) And there were 201 children (25.35%) with PPD positive reactions in northern Jiangsu, 116 children (20.50%) with PPD positive reactions in southern Jiangsu. There were significant differences in the results of PPD positive and negative reactions between different regions(χ2=4.35, P<0.05). There was 1 case of PPD positive reactions among 3-year-old children(0.71%), 19 cases among 4-year-old children(3.89%), 31 cases among 5-year-old children(8.96%), and 37 cases among 6-year-old children(9.63%), and the differences of PPD positive reactions of different age groups were of statistical significance(χ2=21.69, P<0.01). Conclusion The positive rate of PPD in preschool children in Jiangsu Province is very low, indicating that PPD can be used as a detection method for latent infection in children. The overall positive rate of PPD in preschool children in Jiangsu Province is also low, and appropriate measures should be taken to protect susceptible children and effectively prevent and control childhood tuberculosis.

Objective: To explore the association between watching TV and watching computer and visual acuity among children and adolescents, and to provide reference for Chinese students to choose electronic products in life and study. Methods: Subjects were from 2014 Chinese National Surveys on Students’ Constitution and Health(CNSSCH). In this survey, 213 857 Han students participated. The visual acuity results of 5 m visual acuity chart examination were recorded, and the time of completion of homework and the time of different video behaviors were investigated. Results: The incidence of reduced vision acuity among Chinese students increases with the time spent on homework and computer(χ2=3 748.99, 949.39, P<0.01).And it decreased as time spent at the computer increased(χ2=2 725.08, P<0.01). It was found that the incidence of poor vision of students who watched TV for a long time was lower(61.81%), followed by those who watched TV and watched computer for the same time(70.62%), and those who watched computer for a long time(79.03%). The results were statistically significant(χ2=4 862.43, P<0.01). The results of multivariate Logistic regression analysis showed that compared with the students who watched TV for a long time, the students who watched TV for the same time and watched computer for a long time were more likely to have poor vision(OR=1.17, 1.21, P<0.01). Conclusion When using electronic products, the preference of watching large electronic screens is conducive to reducing the impact of video behavior on students' eyesight.

Objective: To understand the prevalence of latent tuberculosis infection (LTBI) among college freshmen in Chaoyang District of Beijing from 2013 to 2015, and to provide evidence for prevention and control of tuberculosis in schools. Methods: The latent tuberculosis infection was identified through a tuberculin purified-protein derivative (TB-PPD) skin test. TB-PPD test results of 65 233 college students in the Chaoyang District during 2013 to 2015 were collected and stored, by using descriptive statistical analysis. Results: Among the 65 233 freshmen, 63 135 were effective PPD test results, 11 754 were PPD positive, 2 720 were PPD strong positive, the LTBI status: the PPD positive rate was 18.62% and the PPD strong positive rate was 4.31%. The positive rate and the strong positive rate in male (19.56%, 4.76%) were higher than that in female(17.87%, 3.95%)(χ2=29.37, 24.29), in ethnic minorities were higher than that in Han Nationality (18.25%,4.16%) and in Tibetans (29.45%, 8.69%) were the highest(χ2=102.01, 70.04), among freshmen from the western region (21.88%, 5.11%)were the highest and from Beijing city (16.25%, 3.46%) were lower (χ2=220.63, 99.03, P<0.01), among those with BCG scar (18.94%, 4.34%) are slightly higher than those without BCG scar(16.96%, 4.08%) (χ2=48.46, 10.43, P<0.01). 19 cases of tuberculosis patients were found, the prevalence rate was 29.13/100 000 (19/65 233), of which 68.42% (13/19) were found through the strong positive for PPD. Among the strong positive students (2 707), there were 1 433(52.94%) who received preventive therapy, and during the follow-up two years, 7 were newly diagnosed with tuberculosis, the annual incidence rate was 129.29/100 000 (7/2 707). Conclusion Freshmen from high-risk areas of tuberculosis are the focus of tuberculosis screening, for which we should continue to carry out PPD screening. Those with latent tuberculosis infection are high-risk groups of tuberculosis, and should be paid more attention in the prevention and control of tuberculosis in schools.

Objective: To investigate the epidemiology and associated factors of deciduous dental caries in 3-5 years old children in Henan Province, and to provide a epidemiological reference for prevention work of deciduous dental caries among children. Methods: According to the basic methods of the Fourth National Oral Health Survey, 12 kindergartens were randomly selected from 2 counties and 2 districts in Henan Province and a total of 1 296 children aged 3-5 years old were randomly selected with stratified multi-stage random sampling method. The deciduous teeth of these children were examined for caries and their guardians were surveyed with questionnaires regarding oral health behavior, knowledge and attitude. Results: Deciduous dental caries occurred in 755 children, accounting for 58.3% and the average decay-missing-filled teeth (dmft) was 2.83. The differences of prevalence of dental caries of boys and girls (60.5%, 56.0%) and mean dmft index (2.88, 2.78) were of no statistical significance(χ2/F=2.64, 0.22, P>0.05). The prevalence of dental caries and mean dmft index for 3, 4 and 5-year-old group was 46.7%, 2.02 and 60.9%, 2.85 and 67.5%, 3.64, respectively. There was statistical significance among three age groups(χ2/F=40.00, 21.68, P<0.01). No significant difference was found in the dental caries prevalence and mean dmft index between urban (58.9%, 2.87) and rural area (57.7%, 2.79)(χ2/F=0.20, 0.16, P>0.05). Multivariate logistic regression showed that age, feeding pattern within the first six months after birth, dental care experience and self-perceived oral health status associated with deciduous caries in 3-5 year-old children in Henan Province(P<0.05). Conclusion Dental caries prevalence is highly prevalent among preschool children in Henan Province. Effective caries precaution measures should be taken to improve oral health level of these children.