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This cross-sectional study was conducted from November 2018 to November 2019 to assess the impact of awareness of sports policies, school, family, and community environmental factors on PA and PF among children and adolescents in China. We employed a stratified cluster random sampling method to ensure a representative sample. Five cities from different regions of China were selected: Shanghai (East), Guangzhou (South), Harbin (Northeast), Yinchuan (Northwest), and Guiyang (Southwest). These cities were chosen to represent diverse geographical, economic, and cultural backgrounds.
Within these cities, we selected ten districts using proportional sampling based on population size. From each district, we randomly selected 3–4 schools encompassing a range of educational levels: primary schools (grade 4), junior middle schools (grade 7), and high schools (grade 10). Ultimately, 17 schools were selected across the ten districts.
The initial sample consisted of 3060 children and adolescents aged 9–18 years. Parents or guardians of each student were also invited to participate in the study to provide information on family environmental factors. Parents were recruited through school notifications and parent-teacher meetings where the study’s objectives and procedures were explained. Participation was voluntary and informed consent was obtained from all parents or guardians. After excluding 268 participants due to incomplete or missing parent questionnaires and 45 students who could not participate in the PF tests due to health reasons, the final sample size for both students and parents was 2747 (effective response rate: 89.8%). The final sample included 1665 children aged 9–12 years (60.6%) and 1082 adolescents aged 13–18 years (39.4%) with a gender distribution of 48.2% males and 51.8% females. The sample comprised 1500 students (54.6%) from urban areas and 1247 students (45.4%) from rural areas (Table 1).
Participants and their parents or guardians completed a comprehensive questionnaire survey to evaluate environmental factors and PA levels, while PF metrics were assessed through on-site testing. The study protocol received approval from the Ethics Committee of the Shanghai University of Sport. Participation was voluntary, with informed oral consent obtained from all children and their parents or guardians. Data were collected and analyzed anonymously to ensure privacy and confidentiality.
Prior to the commencement of this study, comprehensive training was conducted for all individuals involved in administering the questionnaire survey and conducting the PF tests, with all participating researchers being graduate students specializing in sports science. Before initiating the survey and testing, researchers introduced the study objectives and methods to participants in classroom settings. Under guidance, each student completed a 4-page questionnaire within 20 min, either online or on paper, in a classroom or computer lab setting. This questionnaire primarily assessed awareness of sports policies, school, family, and community environmental factors, PA levels, and demographic information. Additionally, parents or guardians of each student were invited to complete a corresponding 4-page home questionnaire, which included questions about parental support for physical exercise and other family-related characteristics. Following the completion of the questionnaire, students underwent PF testing conducted by trained research assistants during scheduled class times.
To ensure the integrity and accuracy of the data collected, a rigorous double data entry system was employed. Two experienced assistants independently input the collected data into a secure computerized database, which was then meticulously cross-checked to ensure consistency and accuracy. Both questionnaire responses and physical test results were encoded with unique identifiers to maintain participant confidentiality. Access to this database was strictly limited to authorized researchers, ensuring data privacy and security.
In this study, awareness of sports policies, school, family, and community environmental factors and PA levels were based on self-reports from survey questionnaires, and PF test was assessed through on-site testing. The specific methodologies for each measurement area are detailed below:
In this study, environmental factors, including awareness of sports policies (Qp), school (Qs), family (Qf), and community (Qc) environments, were assessed using the ‘Child and Adolescent Sports Fitness Survey Questionnaire’ developed by Shanghai University of Sport, which has been extensively utilized nationwide and has demonstrated high reliability and validity [18, 21, 26].
Awareness of Sports Policies (Qp): To assess parents’ awareness of sports policies, we measured their knowledge of the National Physical Fitness Standards for Students (NPFS) and the Interim Measures for the Prevention and Control of Risks in School Physical Activity. Parents responded to two questions designed to gauge their familiarity with these policies.
School Environment (Qs): This term refers to the conditions and factors within the school that influence PA and PF among students. It includes the adequacy of sports facilities and equipment, the impact of PE classes, satisfaction with PE teaching, support from other teachers for engaging in physical exercises, the sufficiency of time allocated for extracurricular physical activities, and the overall exercise atmosphere in the school. Students answered six questions related to these aspects.
Family Environment (Qf): This term encompasses various aspects of parental and family support for children’s PA and PF. It includes parents’ encouragement of their children’s participation in sports, attendance at their sports activities, communication regarding the health benefits of sports, active interest in their children’s PE learning at school, the importance of parental involvement in sports competitions or performances, joint participation in sports activities, accompaniment to sports events, family participation in sports as leisure activities, financial support for sports activities, and leading by example in sports participation. Parents completed a series of ten questions evaluating these aspects.
Community Environment (Qc): This term refers to the broader community factors that influence PA and PF among children and adolescents. It includes the prevalence and quality of youth sports activities in the community or neighborhood, the organization of sports events, the availability of free sports skill training, the establishment of youth sports organizations, and the accessibility to sports facilities suitable for young people. Students were asked four questions about these aspects.
Each of these questions was scored on a five-point scale where 1 equated to 100 points, 2 to 75 points, 3 to 50 points, 4 to 25 points, and 5 to 0 points (Supplementary file). The total scores for each section of the questionnaire were calculated, and the average score for each environmental factor was determined based on these totals.
The modified Chinese-version of the International Physical Activity Questionnaire Short Form (IPAQ-SF) was used to assess the PA levels of the students, which has been used in previous studies [18, 19, 21]. These items facilitated the assessment of activities across three distinct intensity levels: (1) low-intensity activities, such as walking; (2) moderate-intensity activities, such as carrying light loads and cycling at a normal pace; and (3) vigorous-intensity activities, such as running quickly and performing aerobics dance [27]. For each grade level, respondents indicated the frequency (days of engagement in each activity) and duration (minimum of 10 min per session) of these activities over the past seven days. The average daily minutes of low-intensity physical activity (LPA) were calculated by dividing the total minutes of low-intensity activities by seven. Similarly, the average daily minutes of MVPA were obtained by summing the minutes of moderate and vigorous-intensity activities and dividing by seven.
PF indicators in this research were categorized into health-related and performance-related components:
BMI: Children’s barefoot weight (in kilograms) and height (in centimeters) were measured using a portable device (GMCS-IV, Beijing Jianmin Company, China). BMI was calculated as the weight in kilograms divided by the square of height in meters (kg/m2). BMI was categorized based on the “Chinese National Survey on Students’ Constitution and Health” standards, which classify BMI into normal weight, overweight, and obese based on age-specific values [28].
WHtR: WHtR was measured with the participant standing naturally and breathing normally. The tape measure was placed 1 cm above the navel, encircling the body horizontally and passing through the midpoint between the lower margin of the 12th rib and the top of the iliac crest on both sides. The measurement was recorded to the nearest 0.1 mm. WHtR cutoff values for central obesity were based on Chinese reference standards, with 0.48 for boys and 0.46 for girls [29].
Grip Strength: A convenient and effective method for assessing upper limb strength and muscle development, grip strength was measured using a portable dynamometer (T.K.K 5401, Japan). Participants stood with their arms hanging naturally, palms facing inwards, and squeezed the dynamometer with maximum force. The highest value from two attempts for each hand was recorded in kilograms to one decimal point.
Vertical Jump: To evaluate lower limb explosive power and muscle strength, participants performed vertical jumps using a portable device (T.K.K 5406, Japan). The height of the jump was determined by measuring the distance pulled by a connected thread at the peak of the jump. The best of two attempts was recorded in centimeters to one decimal point.
20-mSRT: Used to assess maximal oxygen uptake (VO2max), involved participants running back and forth between two markers 20 m apart with increasing speed every minute starting at 8.5 km/h. The test ended when participants could no longer maintain the pace or elected to stop.
Throughout the survey, demographic information such as age, gender, grade, and residential area (rural or urban) of the participants was collected.
Baseline characteristics and descriptive statistics were calculated to summarize the demographic and main study variables, employing means and standard deviations for continuous data, and frequencies and percentages for categorical data. SEM was employed to investigate the causal relationships among the variables. While SEM allows for the analysis of complex relationships, it is important to note that, due to the cross-sectional design of this study, we cannot establish causal relationships between the independent and outcome variables. Instead, SEM provides insights into the associations and potential pathways between these variables.
The fit of the model to the data was rigorously evaluated using several indices: the chi-square value (χ2), Root Mean Square Error of Approximation (RMSEA), Comparative Fit Index (CFI), and Tucker-Lewis Index (TLI). These indices were employed collectively to assess the adequacy of the model, with a focus on the χ2 value, RMSEA less than 0.08, and CFI and TLI values exceeding 0.90, indicating a well-fitting model. Statistical analyses of baseline features were carried out using SPSS, and SEM was analysed using Mplus version 7.4. The significance threshold for all hypothesis tests was set at α = 0.05, ensuring the statistical validity of the findings.
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