To assess the association between body mass index (BMI) and physical fitness index (PFI) among children and adolescents in Xinjiang Uyghur Autonomous Region, China. In total, 17,618 children and adolescents aged 7–18 years from the selected region were enrolled in this cross-sectional study (8,800 boys and 8,818 girls). Participants were stratified by age and sex and divided into five groups by BMI percentiles: very low (BMI <5th percentile); low, (5th ≤ BMI < 15th percentile); normal (15th ≤ BMI < 85th percentile); high (85th ≤ BMI < 95th percentile); and very high (BMI ≥95th percentile). PFI was assessed by height, weight, and five health-related fitness indicators (grip strength, standing long jump, sit and reach, 50 m dash, and endurance run). BMI was significantly associated with PFI during adolescence (13–18 years) in boys and pre-adolescence (7–12 years) in girls. Between the ages of 13 and 18 years, an increase in BMI had a greater impact on PFI in boys than girls. PFI showed a parabolic curvilinear relationship with BMI. Children and adolescents in China’s Xinjiang Uyghur Autonomous Region with a normal BMI demonstrated good physical fitness. A BMI below or above the normal range may contribute to poor physical fitness. The relationship between BMI and PFI shows an inverted U-shaped curve.

We assessed trends in physical fitness by age group and nutrition status among children and adolescents in Xinjiang during 1985–2014. The data of 49,357 participants aged 7–18 were extracted in 1985, 1995, 2005, and 2014. Growth and nutritional status were defined using World Health Organization definitions. A physical fitness indicator (PFI) was calculated as the sum of six components measured in every survey. The relationship between body mass index (BMI) and PFI was investigated using nonlinear regression. Taking 1985 as a reference, PFI increased to 2 in 1995 and then fell sharply to −2.8 in 2005 and −3.8 in 2014. The prevalence of normal weight increased from 87.5% in 1985 to 89.4% in 1995 and then decreased to 75.2%, consistent with the change in PFI. The relationship between BMI and PFI showed an inverted U-shaped curve. The largest increment occurred in boys aged 13–15 and girls aged 16–18 during 1985–1995; the largest decline occurred in boys and girls aged 10–12 during 1995–2005. Our research provides a reference for local governments providing nutrition subsidies and projects in southern Xinjiang, indicating that greater attention is needed for children aged 7–12.

Background: Mental disorders among adolescents have become a worldwide public health problem. This study aimed to estimate the best combination of exercise time and screen time to promote the mental health of Chinese adolescents. Methods: Participants included 7200 Chinese adolescents aged 13–18 years from six regions of China. Screen and exercise time data were collected via a self-rated questionnaire. Psychological symptoms (e.g., often feeling depressed, school-weary) were evaluated with the “Multidimensional Sub-health Questionnaire of Adolescents”. Chi-squared tests and logistic regression analysis were conducted to investigate the differences in and correlations among screen time, exercise time, and psychological symptoms. Results: The overall detection rate of psychological symptoms among Chinese adolescents was 21.4% (22.1% for boys and 20.6% for girls). Psychological symptom detection rates were lowest among adolescents with 1–2 h/d of screen time (19.5%) and those with 30–60 min/d of exercise time (17.3%). Screen time > 2 h/d (OR = 1.38, P < 0.001) and exercise time < 30 min/d (OR = 1.62, P < 0.001) were positively correlated with psychological symptoms. Conclusion: Screen and exercise time are associated with psychological symptoms in Chinese adolescents. A combination of 1–2 h/d of screen time and 30–60 min/d of exercise time is provided as a reference for better mental health.

This study aimed to explore the impact of environmental factors such as latitude, altitude, family socioeconomic status (SES), and level of urbanization on overweight and obesity (ow/ob) in children and adolescents. The participants comprised 26,120 children and adolescents aged 10–18 from 16 provinces in China. Differences in the prevalence of ow/ob under different environmental conditions were evaluated by the chi-square test. The influence of various environmental factors on ow/ob was obtained by logistic regression analysis. We found that (1) the prevalence of ow/ob fell between from 19.2% to 11.9% at 10 years old and from 13.8% to 6% at 18 years old; (2) latitude, family SES, income, and urbanization level are positively correlated with the prevalence of ow/ob; and (3) altitude has a negative correlation with the prevalence of ow/ob. The prevalence of ow/ob decreased with age in children and adolescents aged 10–18, and the risk of ow/ob showed significant differences in latitude, altitude, family SES level, gross domestic product (GDP), and level of urbanization.

Since the beginning of the 21st century, China’s economy has experienced rapid growth, resulting in a steady improvement in its citizens’ living standards. However, alongside the emergence of modern civilization-related health issues, the overall physical fitness of the population has been declining. In the final year of 2019, a global COVID-19 pandemic emerged and persisted for three years, causing a significant diminution in human physical well-being. This article aims to delve into the changes in the physical fitness of college students over the past decade and anticipates future trends. A total of 58,472 university students aged 16–23 from 16 prefecture-level cities in Anhui province were recruited for this study. Total ten physical fitness indicators were tested: body height, body weight, vital capacity, standing long jump, sit-and-reach, 50-m dash, 1000 m run and pull-up (for boys), and 800 m run and sit-ups (for girls).The data were analyzed using one-way ANOVA, LSD tests, and Pearson’s correlations. The overall physical fitness scores of college students ranged from 68.71 (2023) to 71.13 (2019) during the last decade, with girls consistently demonstrating superior performance in physical tests. There was a statistically significant difference in physical fitness scores between the periods of 2015–2022 and 2023 (p < 0.05). When dividing the total physical fitness scores into four levels, a noteworthy downward trend was observed in the pass grade, while the other three grades exhibited an increasing trend year by year. Compared to the year of 2019, there has been a substantial decline in the physical fitness levels of college students, along with a notable uptick of “failed” candidates, in the year of 2020.In terms of individual physical fitness, boys outperformed girls in all physical testing items except for sit-and-reach, and significant differences were observed in most years for both boys and girls. Additionally, a consistent downward trend was observed in the proportion of underweight and normal weight students, while the proportion of overweight (increased by 2.1 times) and obese (increased by 4.4 times) students showed a marked upward trend from 2014 to 2023. It is imperative to allocate special focus to the profound ramifications of the three-year COVIE-19 pandemic on the physical well-being of college students. In 2024, it is anticipated that the proportion of overweight and obese college students will increase, along with a continued increase in body height and vital capacity. However, there will be a notable increase in the time taken to complete the 50-meter dash and the 1000-meter/800-meter run. Conversely, a decline is forecasted for the performance in standing long jump, sit-and-reach, and pull-ups/sit-ups exercises, with an accelerating rate of deterioration. It is crucial to promptly identify the underlying reasons for the deteriorating physical fitness among college students, particularly in relation to obesity, and to implement effective measures promptly to address this issue.