Combined Effect of Outdoor Time and Other Modifiable Factors on Myopia Incidence Among Children and Adolescents - 9 PLADs, China, 2020.

What is already known about this topic?: Myopia has been identified as a significant emerging challenge and policy priority among children and adolescents in China by the Ministry of Education and seven other departments. Limited research has been conducted to investigate the collective impact of outdoor time and other modifiable factors on the incidence of myopia. What is added by this report?: This study provides support for the protective effect of combining increased outdoor time with other prevention strategies in reducing the incidence of myopia. The results indicate the presence of a dose-response relationship. What are the implications for public health practice?: To effectively prevent myopia, it is important to implement comprehensive interventions that encompass various aspects such as outdoor time, eye-use habits, eye-use environments, and lifestyle modifications.

24-H movement behaviors and physical fitness in preschoolers: A compositional and isotemporal reallocation analysis.

Background/Objectives: This study examined the relationships between 24-h movement behaviors and physical fitness (PF) in preschool children. Methods: The study was conducted on 474 children aged 3-6 years in Zhuhai. Physical activity (PA) and sedentary behavior (SB) were collected by the accelerometer, and sleep time was assessed through the parent-report questionnaire. Balance, cardiorespiratory fitness (CRF), flexibility, muscle strength, muscular endurance, and speed-agility were measured using a balance beam test, 20 m shuttle run test, sit and reach test, handgrip test, sit-ups, and 4 × 10 m shuttle run test respectively. The compositional data analysis was used to examine the association between 24-h movement behaviors and PF, and the compositional isotemporal substitution analysis was used for the time reallocation. Results: The daily composition, adjusted for age, gender, and body mass index (BMI), was significantly associated with CRF (p < 0.001, r2 = 0.20), flexibility (p < 0.001, r2 = 0.07), muscular strength (p < 0.001, r2 = 0.37), muscular endurance (p < 0.001, r2 = 0.26), and speed-agility (p < 0.001, r2 = 0.26). The addition of moderate-to-vigorous PA (MVPA) at the expense of SB and sleep, MVPA at the cost of sleep, was associated with significant muscular strength and speed-agility improvements respectively. The impact of SB and sleep replacing MVPA is stronger than MVPA replacing SB and sleep on muscular strength. Conclusion: These findings offer useful insight for the replacement of movement behaviors within the recommended range to facilitate PF development in early childhood.

Associations of school physical activity environment with comorbid obesity and myopia in children and adolescents: Findings from a Chinese national follow-up study.

BACKGROUND: Overweight and obesity (OWOB) and myopia have become two of the most important issues affecting the health of children and adolescents worldwide. Despite the recognition that the school physical activity (PA) environment is a critical factor for preventing and controlling overweight, obesity (OWOB), and myopia in children and adolescents, research on OWOB and myopia as a comorbidity remains unexplored, with evidence for effective strategies still being inconclusive. Hence, this study aimed to assess the prevalence and progression of comorbid OWOB/myopia and each condition alone, and to explore the association with school PA environment. METHODS: A total of 9814 children and adolescents aged 6-18 years were included from the Chinese National Survey on Students' Constitution and Health follow-up survey conducted from November 2019 to November 2020 in China. Anthropometric measurements, unaided distance vision acuity and non-cycloplegic refraction data were collected to assess OWOB and myopia, while eight indicators from questionnaires for children and adolescents aged 9-18 years were investigated to assess school PA environment. We calculated the one-year incidence and progression rates of comorbid OWOB/myopia, OWOB alone, and myopia alone. Mixed effect logistic regression was evaluated the association between school PA environment and incidence and progression of comorbid OWOB/myopia, OWOB, and myopia. RESULTS: The prevalence of comorbid OWOB/myopia increased from 11.1% in 2019 to 17.9% in 2020, and the incidence of comorbid OWOB/myopia was 10.9%. Children and adolescents experiencing an unfavorable school PA environment had a higher risk of the incidence of comorbid OWOB/myopia compared to a favorable school environment (OR = 1.85, 95% CI: 1.42-2.42). Similar findings were seen in the incidence of obesity (OR = 1.86, 95% CI: 1.26-2.75). Children and adolescents in an unfavorable school PA environment had a higher risk of myopia progression (OR = 1.29, 95% CI: 1.01-1.65). CONCLUSIONS: Obesity and myopia and their comorbidity have been serious among children and adolescents in China. A favorable school PA environment might mitigate the risk of comorbid OWOB/myopia, OWOB, and myopia progression.

24-Hour movement behaviors and executive functions in preschoolers: A compositional and isotemporal reallocation analysis.

This cross-sectional study explored the relationship between 24-hour movement behaviors and executive function (EF) in preschool children. A total of 426 Han Chinese preschoolers (231 males; 3.8 ± 0.6 years old) from Zhuhai, Guangdong Province, China were selected from October 2021 to December 2021. Accelerometers were used to measure physical activity (PA) and sedentary behavior (SB), while sleep duration was obtained via a parent-report questionnaire. Components of EF (cognitive flexibility, inhibitory control, and working memory) were assessed using computerized behavioral tasks. The daily composition was significantly associated with inhibitory control and working memory. Inhibitory control improvements were linked to the addition of moderate-to-vigorous physical activity (MVPA) at the expense of SB and sleep. The reallocation between MVPA, SB, sleep, and light physical activity yielded a significant association with working memory.

Do acute and chronic physical activity interventions affect the cognitive function of preschool children? A meta-analysis.

This meta-analysis aims to investigate the effects of acute and chronic physical activity (PA) interventions on multiple domains of cognitive function (CF) in preschool children. Electronic databases (PsycINFO, PubMed, SPORTDiscus, Embase, Web of Science, MEDLINE, and ERIC) were searched for relevant studies between January 2000 and February 2022. Studies that examined the effects of acute or chronic physical activity interventions on CF in preschool children aged 2-6 years were included. A total of 16 articles were eligible for this meta-analysis. Results showed that there was no effect of acute PA interventions on CF (Hedges' g = 0.04; 95% CI = -0.12, 0.19). Chronic PA interventions had a moderate and positive effect on overall CF (Hedges' g = 0.49; 95% CI = 0.29, 0.69), a large effect on perception (Hedges' g = 1.19; 95% CI = 0.64, 1.75), and a moderate effect on inhibitory control (Hedges' g = 0.73; 95% CI = 0.22, 1.24). The moderator analyses showed that overall CF performance was significantly moderated by intervention modality and assessment of cognitive outcomes, and no other moderator (study design, sample size, frequency, duration, and session length) was found to have an effect. Chronic PA intervention might be a promising way to promote multiple aspects of CF, especially executive function and perception. Future studies should explore the effect of different intensities of PA on the CF of preschool children to discern the most effective PA prescription to, in turn, enhance the CF of preschool children.

Associations between exposure to ambient particulate matter and advanced liver fibrosis in Chinese MAFLD patients.

BACKGROUND & AIMS: Liver fibrosis is an important feature in patients with metabolic dysfunction-associated fatty liver disease (MAFLD). This study aimed to explore the association between long-term ambient particulate matter (PM) exposure and advanced liver fibrosis (ALF) in MAFLD participants. METHODS: A cross-sectional study of 23170 adults recruited from 33 provinces of China from 2010 to 2020. ALF was detected using the nonalcoholic fatty liver disease fibrosis score (NFS). The annual average levels of particulate matter with aerodynamic diameters of ≤ 1 µm (PM1), ≤ 2.5 µm (PM2.5) and ≤ 10 µm (PM10) were calculated using validated spatiotemporal models. Generalized additive models were applied to analyze the association between PM and ALF in patients with MAFLD. RESULTS: One-year exposure to higher levels of all PM was found to increase the risk of ALF, with odds ratios (ORs) of 1.10 (95% CI 1.06-1.14), 1.05 (1.03-1.07), and 1.03(1.02-1.04) for each 10 µg/m3 increase in PM1, PM2.5 and PM10, respectively. With the dissection of the impact of PM1 in PM2.5, PM2.5 in PM10 and PM1 in PM10, we found that PM2.5 had a stronger impact on ALF (both Pinteraction＜0.05) in comparison with PM1 and PM10. CONCLUSIONS: Long-term exposure to PM is associated with ALF in patients with MAFLD, with PM2.5 playing a dominant role.

Association between early life exposure to the great famine and possible sarcopenia in older Chinese adults: a national cross-sectional study.

OBJECTIVES: We used data from the China Health and Retirement Longitudinal Study (CHARLS) to investigate how an early life famine exposure affected possible sarcopenia (PS) and to explore the extent to which a sex difference exists in the association among older Chinese adults, as well as whether risk factors modify the association. DESIGN: Cross-sectional study. SETTING: 28 provinces of China. PARTICIPANTS: Considering that the Great Chinese Famine lasted from the spring of 1959 to the fall of 1961, 3557 participants were selected and categorised into four subgroups based on their date of birth: unexposed group (1 October 1962 to 30 September 1964), fetal exposed group (1 October 1959 to 30 September 1961), infant exposed group (1 January 1958 to 31 December 1958) and preschool exposed group (1 January 1956 to 31 December 1957). OUTCOME MEASURE: PS was defined as having low muscle strength or low physical performance. METHODS: We used multivariable logistic models to analyse the association between early life famine exposure and the risk of PS in elderly life. RESULTS: The prevalences of PS among individuals in the unexposed, fetal, infant and preschool exposed groups were 15.1%, 14.4%, 23.6% and 21.9%, respectively. Compared with the unexposed group, the infant (OR: 1.55; 95% CI 1.17 to 2.05) and preschool exposed (OR: 1.46; 95% CI 1.17 to 1.82) groups exhibited significantly higher risks of PS. In men, the infant (OR: 2.15; 95% CI 1.40 to 3.31) and preschool exposed (OR: 1.78; 95% CI 1.23 to 2.57) groups were more likely to have PS, but no significant increase was seen in women. In both sexes, prevalence of PS was unrelated to early life famine exposure in the urban, underweight and normal weight subgroups. CONCLUSIONS: Early life exposure to the Great Chinese Famine was associated with a higher risk of PS in older adults. Keeping normal nutritional status in elderly life might help avoid the risk of PS, whatever the effect of early famine exposure.

Artificial Light-at-Night Exposure and Overweight and Obesity across GDP Levels among Chinese Children and Adolescents.

BACKGROUND: Evidence in adults suggests that exposure to artificial light-at-night (ALAN) leads to obesity. However, little is known about whether this effect exists in children and adolescents. We aimed to investigate whether ALAN exposure was associated with overweight and obesity in school-aged children and adolescents and whether this association varied with socioeconomic status. METHODS: Data on the height and weight of 129,500 children and adolescents aged 10-18 years from 72 cities were extracted from the 2014 Chinese National Survey on Students' Constitution and Health (CNSSCH). The ALAN area percentage and average ALAN intensity were calculated using the Visible/Infrared Imager/Radiometer Suite. The subjects were separated into three categories based on the cities' gross domestic product per capita (GDPPC). A mixed-effect logistic regression model and generalized additive model (GAM) were utilized to evaluate the association between ALAN exposure and overweight and obesity in children and adolescents stratified by municipal GDPPC. RESULTS: Both ALAN area (OR = 1.194, 95% CI: 1.175-1.212) and ALAN intensity (OR = 1.019, 95% CI: 1.017-1.020) were positively associated with overweight and obesity in children and adolescents, and the associations remained robust after adjusting for covariates. ORs for overweight and obesity and ALAN area decreased as GDPPC level increased (first tertile: OR = 1.457, 95% CI: 1.335-1.590; second tertile: OR = 1.350, 95% CI: 1.245-1.464; third tertile: OR = 1.100, 95% CI: 1.081-1.119). Similar results were observed for ALAN intensity. In the GAM models, thresholds existed in almost all these spline trends, indicating that ALAN might have a nonlinear association with overweight and obesity. CONCLUSIONS: ALAN contributed to the development of overweight and obesity in children and adolescents and this effect differed with GDPPC. Future longitudinal studies should confirm the causal relationship between ALAN and obesity. Moreover, reducing unnecessary exposure to artificial light at night may have beneficial implications for controlling childhood and adolescent obesity, particularly in low-income areas.

Association of fast-food restaurants with overweight and obesity in school-aged children and adolescents: A systematic review and meta-analysis.

We aimed to explore associations between the accessibility of fast-food restaurants (FFRs) and weight-related outcomes in children and adolescents through a systematic review and meta-analysis of studies. We searched three databases for studies published before October 21, 2022. Study quality was assessed using the National Institutes of Health's Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Meta-analysis was performed, and the leave-one-out method was used for sensitivity analysis. A total of 60 studies were included. According to our analysis, FFRs within a smaller buffer radius from residences or that provide unhealthy foods may have a more significant influence on children's and adolescents' weight. Children of younger ages and girls may have a higher possibility of being overweight due to FFRs. Though we could hardly avoid bias, the estimates in low-and middle-income countries (only six studies) are much higher than those in high-income countries (54 studies). More research analyses based on microscope data and individual economic levels are needed. This study yields quantitative results, provides policymakers and urban planners with a theoretical support for building resilient and sustainable human settlements, and promotes the translation of research findings from public health to environmental planning.

Secular trend and urban-rural disparity for age at spermarche among Chinese Han boys from 1995 to 2019.

AIM: To examine the secular trend and the urban-rural disparity of spermarche among Chinese Han boys from 1995 to 2019. METHODS: A total of 392 775 boys of Han ethnicity aged 11-18 years were extracted from the 1995, 2000, 2005, 2010, 2014 and 2019 Chinese National Surveys on Students' Constitution and Health. The median age at spermarche was estimated using the status quo data and probit analysis. The chi-square, ANOVA and LSD tests were used to compare the differences between the year-subgroups. U-test was used to compare the difference between urban and rural areas at each year. RESULTS: The median age at spermarche in Chinese Han boys decreased from 14.6 years in 1995 to 13.9 years in 2019 (p < 0.001). The rural boys showed a faster decreasing pace with a 1-year advance of age at spermarche while the urban boys had only a 0.5-year decrement, and there was still a statistically significant difference between urban-rural areas in 2019 (p < 0.001). Similar to urban-rural disparity, the age gap at spermarche between areas with different urbanisation rates became smaller over time. CONCLUSIONS: In general, spermarche in Chinese Han boys showed a decreasing trend, but the pace was slowing down. The urban-rural disparity in puberty development still existed but was gradually narrowing.

The effectiveness of Facebook as a social network intervention to increase physical activity in Chinese young adults.

Introduction: Facebook, one of the worlds' most popular online social networks, is easy to access and cost-effective. Its use to enhance individual's physical activity (PA) participation should be examined. This research reviews the effectiveness and successful features of Facebook for influencing PA behaviors in young adults (Study 1), and empirically examines the efficacy of the features purported in increase PA via a Facebook intervention (Study 2). Methods: In Study 1, PubMed, Medline, SPORT Discus, ERIC, and Embase were searched for articles that identified successful features and effectiveness of Facebook PA interventions published between January 2005 and February 2022. In Study 2, a 4-week Facebook PA intervention with University students was conducted using features identified in Study 1. The PA behaviors with objective (ActiGraph) and subjective (questionnaire) measures, perceived PA level, stage of readiness, effectiveness, and efficiency of Facebook were examined. Results: Study 1 concluded that the most effective strategies for producing significant PA changes in young adults using a PA Facebook intervention included the following: Adding behavior modification (goal setting and self-monitoring), using influence agents, recruiting members of an existing network with the snowball technique, being attentive to group size, enhancing social support with motivational quotes, interactive posts, opinion polls, increasing tailored feedback, and providing educational information. Study 2 found no significant difference in PA between the intervention and the control groups, as measured objectively, but the subjective reporting of PA behavior was higher in the intervention group. Compared to the control group, the Facebook PA intervention group reported more positive change in perceived stage of readiness in PA participation, commuting type, sport type, sport venue, sport emotion, and fast breathing or sweating. When features were ranked by the Facebook PA intervention group, motivation (supports from your friends) and tailored feedback (the responses from your friends are really personal and fits you) were the top two ranked features. Conclusion: The use of influence agents in the Facebook PA intervention could address exercise preference and facilitate higher program engagement. Significant differences related to commuting type, sport types, sport venue barriers, and exercise intensity across groups were noteworthy and warrant additional investigation in the future.

Combined Associations of Smoking and Bullying Victimization With Binge Drinking Among Adolescents in Beijing, China.

Background: Binge drinking and smoking among adolescents are serious public concerns. However, very few studies have explored the reinforcement of bullying victimization by such behavior. Our study aimed at examining the individual and combined associations of smoking and bullying victimization with binge drinking among adolescents in Beijing, China. Methods: A total of 33,694 students aged 13-17 years old in Beijing, China were anonymously investigated via the cross-sectional Chinese Youth Risk Behavior Surveillance Survey from April to May 2014. A three-stage stratified sampling was used to select participants. Factors such as sociodemographic variables and indicators of smoking, bullying victimization, and binge drinking were analyzed with multiple logistic regressions, and joint and additive interaction effects were tested. Results: Overall, ever-drinking prevalence was 59.1% (boys: 64.4%; girls: 53.7%). Past 30-day binge drinking was 11.5% (boys: 15.6%; girls: 7.4%) and frequent binge drinking was 2.3% (boys: 3.3%; girls: 1.0%). Past 30-day smoking was 10.7% (boys: 16.4%; girls: 5.0%) and past 30-day bullying victimization was 48.7% (boys: 57.3%; girls: 40.1%). The combined effects of smoking and bullying victimization on occasional binge drinking (OR = 6.49, 95% CI = 5.60-7.52) and frequent binge drinking (OR = 10.32, 95% CI = 7.52-14.14) were significant, and the additive interaction effect was significant for current smoking and bullying victimization on frequent binge drinking (OR = 10.22, 95% CI = 9.43-11.07). The additive interaction effect for current smoking and bullying victimization on frequent binge drinking was significant among boys. Conclusion: Bullying victimization reinforced the association of smoking with frequent binge drinking, especially with findings specific to boys. Programs to prevent smoking or bullying or both may reduce binge drinking among adolescents in China.

Individual-, Family-, and School-Level Ecological Correlates With Physical Fitness Among Chinese School-Aged Children and Adolescents: A National Cross-Sectional Survey in 2014.

Introduction: Few studies have examined the association between the individual-, family-, and school-level ecological correlates and physical fitness among Chinese children and adolescents, which is the purpose of the present study. Methods: A total of 157,168 children and adolescents, 10-18 years of age, with physical fitness data in 2014, participated in the study. Physical fitness was assessed, using six tests: forced vital capacity, standing long jump, sit and reach, body muscle strength, 50-m dash, and endurance running. Scores were aggregated to form a summary physical fitness indicator (PFI), which was then classified into five levels: low, low-middle, middle, middle-high, and high. Each option of individual-, family-, and school-level measures were constructed into a positive or negative correlate of physical fitness and then accumulated as a composite ecological score. Results: Among the 20 individual-, family-, and school-level correlates, 18 were found to be significantly associated with PFI, with high PFI levels being correlated with the positive group of correlates and low PFI levels correlated with the negative group of correlates (p < 0.05). High scores of ecological correlates were associated with a high level of PFI [adjusted odds ratio (OR) = 1.06, 95% CI: 1.06, 1.07)] whereas low scores were associated with a low level of PFI (OR = 0.95, 95% CI:0.95, 0.95). The ecological correlates at the individual, school- and family-levels were shown to be significantly related to high PFI among Chinese children and adolescents aged 10-18 years with different ORs of 5.97 (95% CI: 5.51, 6.47), 3.94 (3.66, 4.24), and 1.25 (1.19, 1.31). The PAR% of 20 cumulative factors effects due to the negative and positive responses for low PFI levels were 35.9 and 16.1%, and, for high PFI levels, were 15.3 and 24.1%, among Chinese children and adolescents, respectively. Compared with the correlates at family and school levels, the correlates at individual levels had the largest PAR%. Conclusion: Individual-, family-, and school-multilevel factors had a significant cumulative association with either improving or worsening aspects of physical fitness. Individual level factors remain at the core of physical fitness improvement. Comprehensive policies and measures are urgently needed to enhance the physical fitness of Chinese children and adolescents through involving further individual and environmental factors.

Geographical Variation in Physical Fitness Among Chinese Children and Adolescents From 2005 to 2014.

Introduction: To examine the geographical variation in change in the levels of physical fitness from 2005 to 2014 among Chinese children and adolescents. Methods: A total of 663,813 children 7 to 18 years of age with physical fitness data in 2005, 2010 and 2014, participated in the study. Physical fitness was assessed using six components, and their standardized scores were aggregated to form a summary physical fitness indicator (PFI). Results: Over the study period, there was an increase in the proportion of high PFI (from 15.3% in 2005 to 19.0% in 2014, Ptrend < 0.05) and a decrease in the proportion of low PFI (from 30.6 to 29.8%, Ptrend < 0.05). Children and adolescents in the eastern provinces of China showed a high proportion of high PFI with an increasing trend over time, while those in the western provinces had a high proportion of low PFI with a decreasing trend over time (P < 0.05). Conclusions: The comprehensive physical fitness among Chinese children showed an improved trend from 2005 to 2014. Region-specific interventions with priority policies could be useful to sustainably narrow geographical variation in Chinese children, especially in the western provinces.

Prevalence of Internet Addiction and Its Relationship With Combinations of Physical Activity and Screen-Based Sedentary Behavior Among Adolescents in China.

BACKGROUND: Given the widespread prevalence and serious nature of Internet addiction (IA), this study aimed to estimate the prevalence of IA and assess the relationships between IA and combinations of physical activity (PA) and screen-based sedentary behavior (SB) among adolescents in China. METHODS: This cross-sectional study surveyed 31,954 adolescents in grades 7 to 12 in Beijing. IA, PA, screen-based SB, and other information were obtained from a self-administrated questionnaire. The chi-square test and mixed-effects logistic regression model were applied to estimate the relationship between IA and combinations of PA and screen-based SB. RESULTS: 6.2% of the surveyed adolescents reported IA and the prevalence of low PA/high screen-based SB, high PA/high screen-based SB, low PA/low screen-based SB, and high PA/low screen-based SB were 53.7%, 19.5%, 18.8%, and 8.0%, respectively. Mixed-effects logistic regression analysis showed that adolescents with low PA/high screen-based SB were 1.99 (95% confidence interval, 1.62-2.44, P < .001) times more likely to prefer IA than those with high PA/low screen-based SB. CONCLUSIONS: The prevalence of IA among Chinese adolescents is still high. Intervention programs like maintaining sufficient PA and reducing screen-based SB might contribute to reducing their IA.

Percentile Curves for Multiple Physical Fitness Components Among Chinese Han Children and Adolescents Aged 7-18 Years From a National Survey Based on the Total and the Normal Weight Population.

Introduction: To develop sex- and age-specific percentile curves for seven physical fitness components for Chinese Han children and adolescents aged 7-18 years based on the total and the normal weight population using a nationally representative sample. Methods: A total of 214,228 Chinese Han children and adolescents aged 7-18 years old with all nutritional status and 161,999 with normal weight were examined. Seven physical fitness components [forced vital capacity (FVC), standing long jump (SLJ), 50-m dash, sit-and-reach (SR), grip strength (GS), body muscle strength (BMS), and endurance running (ER)] were measured, and percentile curves for each physical fitness component at the 20th, 40th, 60th, and 80th percentiles were calculated using the general additive model for location, scale, and shape (GAMLSS). Results: Physical fitness presents different characteristics in each subgroup of sex, age, and nutritional status among children and adolescents. Sex- and age-specific percentiles for the seven physical fitness components among the Chinese Han children and adolescents aged 7-18 years based on the total and the normal weight population were provided as curves. Boys performed better than girls in FVC, SLJ, 50-m dash, GS, and ER but worse in SR. The performances of FVC, SLJ, 50-m dash, GS, BMS, and ER increased with age, but the estimates of SR were at the bottom among boys aged 12 years and girls aged 11 years. The annual increments of all components were larger in boys than girls at the peak time, which was earlier in girls than boys. The gap of physical fitness components between sexes increased with age, especially during puberty (since after 11 years old). Conclusion: The present study described the percentile curves of seven physical fitness components among the Chinese Han children and adolescents based on the total and the normal weight population at the national level, which could help to chart the level of physical fitness across age span and identify the extreme populations with either health concerns or potential talents.

The mean age of menarche among Chinese schoolgirls declined by 6 months from 2005 to 2014.

AIM: This study assessed the trends in the age at menarche in Chinese schoolgirls from the majority Han group and 21 ethnic minorities from 2005 to 2014. We also compared the group differences during the study period. METHODS: A total of 344 230 girls aged 9-18 years were extracted from the 2005, 2010 and 2014 Chinese National Survey on Students' Constitution and Health. The age at menarche for each subgroup was estimated by probit analysis. The chi-square test and Z-test were used to compare the differences between the groups. RESULTS: The overall average age at menarche in Chinese schoolgirls decreased from 12.8 years in 2005 to 12.3 years in 2014. The Han girls and girls from 17 ethnic minorities showed decreasing trends in the age at menarche, while four ethnic minorities demonstrated fluctuating increasing trends over time. The gaps in age at menarche between the Han group and 14 of the ethnic minorities became smaller over the study period and were similar by 2014. CONCLUSION: The overall findings were a decrease in the age at menarche in China and smaller gaps between the majority Han group and ethnic minority groups. Ethnic-specific public health policies are urgently needed on issues such as contraception.

Getting Active with Active Video Games: A Quasi-Experimental Study.

Given the cultural emphasis on academic achievement and environmental constraints to physical activity (PA), active video games (AVGs) may be used to decrease sedentary behavior and increase PA of Hong Kong children. This study explored the potential of a school-based AVG intervention on sedentary time, PA, body composition, and psychosocial factors among children. Eighty-seven children (intervention n = 30) were recruited from one primary school. Classes in Grades 4-6 were allocated to either the intervention group or the control group in a 2:1 ratio. The eight-week intervention involved children playing AVGs in an after-school class twice a week. Participants in the control group continued with their usual activities. Outcome included the change of participants in sedentary time, PA, percentage body fat, body mass index (BMI), and psychosocial variables (enjoyment, self-efficacy and social support), from baseline to eight weeks. No significant group differences were observed in sedentary time (-33.9 min/day, 95% CI -70.8 to 4.8; p = 0.07). The intervention group significantly increased total PA (53.7 counts/min, 95% CI 8.6 to 104.2; p = 0.04) compared with those in the control condition. No differences were found in body composition and psychosocial variables. However, significant treatment effects were found on BMI z score among boys (-0.1, 95% CI -0.2 to 0; p = 0.04). An eight-week school-based AVG intervention delivered during after-school hours was effective in increasing activity levels among Hong Kong children. The treatment effects of AVGs on sedentary behavior and body composition need to be further demonstrated in a more robust study, especially in boys.

Reducing Anemia Among School-Aged Children in China by Eliminating the Geographic Disparity and Ameliorating Stunting: Evidence From a National Survey.

Background: The aim of this study was to assess the geographic disparity in anemia and whether stunting was associated with anemia in different geographic groups among school-aged children in China. Methods: 71,129 Han children aged 7, 9, 12, and 14 years old were extracted from the 2014 cycle of Chinese National Surveys on Children Constitution and Health. Anemia, anemia severity, and stunting were defined according to WHO definitions. Binary logistic regression models were used to estimate the association between anemia and stunting in different geographic groups. Results: The prevalence of anemia was significantly higher in girls (10.8%) than boys (7.0%). The highest anemia prevalence was in Group VII (lower class/rural, 12.0%). A moderate/severe prevalence of anemia was concentrated in Group VII and Group VIII (western/lower class/rural) for both sexes. The prevalence of anemia was higher in stunting boys than non-stunting boys in Group IV (lower class/city, χ2 = 12.78, P = 0.002) and Group VII (χ2 = 6.21, P = 0.018), while for girls, it was higher in stunting girls than their non-stunting peers only in Group II (upper class/large city, χ2 = 4.57, P = 0.046). Logistic regression showed that the stunting children have 30% higher risk of anemia than non-stunting children after adjustment for age, sex and school (OR = 1.30, 95% CI: 1.05-1.60). Conclusion: A significant geographic disparity and an association between anemia and stunting among specific groups of school-aged children in China was demonstrated. Consequently, eliminating the geographic disparity and ameliorating stunting might contribute to the improvement of Chinese children's anemia. Specific guidelines and interventions are needed, especially for adolescent girls and the groups with serious anemia burden.

Trends in physical fitness, growth, and nutritional status of Chinese children and adolescents: a retrospective analysis of 1·5 million students from six successive national surveys between 1985 and 2014.

BACKGROUND: Physical fitness is strongly associated with health. Despite the extent of the nutritional transition from food scarcity to diets high in fats and refined carbohydrates that has occurred in China, to our knowledge, trends in physical fitness have not been described. We aimed to assess trends in physical fitness and its association with the nutritional transition among Chinese children and adolescents. METHODS: In this retrospective analysis, data from Chinese school students aged 7-18 years were extracted from six successive national surveys undertaken between 1985 and 2014. Six components of physical fitness (forced vital capacity, standing long jump, sit-and-reach, body muscle strength, 50 m dash, and endurance running) were measured repeatedly in each survey and aggregated as a summary physical fitness indicator (PFI). Growth and nutritional status (stunting, thinness, normal weight, overweight, and obesity) were defined by use of WHO definitions, and we combined stunting and thinness as undernutrition and overweight and obesity as overnutrition. Urbanisation levels were obtained from the statistical yearbook of the National and Provincial Bureau of Statistics of China. We used fractional polynomial regression and generalised additive models to assess associations between PFI and nutritional outcomes and between PFI and levels of urbanisation. FINDINGS: Between 1985 and 2014, 1 513 435 students participated in the Chinese National Survey on Students' Constitution and Health, and 1 494 485 were included in our study. We observed a decline of the PFI during 1985-2014 (overall PFI change -0·8), albeit with an increase from 1985 to 1995 (PFI change 1·2), coinciding with a shift in the major nutritional problems from stunting and thinness to overweight and obesity. Both undernourished (PFI -2·44 for thin and -3·42 for stunting) and overnourished (-1·49 for overweight and -3·63 for obese) students had a lower PFI than that of those with normal weight (-0·41) in 2014. Boys had a larger decline in PFI than girls in 1985-2014, especially boys with obesity (PFI change -2·7). We observed the highest PFI in 1995 (1·17), when the proportion of students with normal weight was highest. Advancing urbanisation was accompanied by declines in physical fitness, which occurred in both students in rural settings and those in urban settings in these regions. INTERPRETATION: Our study supports the continuation of policies to improve physical fitness that focus on undernutrition, including economic subsidies, in poorer rural regions. However, for most of China, taxation of unhealthy foods, promotion of physical activity, reduction in academic pressures, promotion of dietary diversity, reduction of sedentary time, and engagement in formal sporting activities should be elements of policies to promote healthy weight status and prevent obesity in school students, which will also support physical fitness. FUNDING: National Natural Science Foundation, Humanities and Social Sciences Planning Fund Project, China Scholarship Council, and Innovation Fund for Outstanding Doctoral Candidates of Peking University Health Science Center.