Trends and Associations of Physical Fitness and Dietary Behaviors Among Children Aged 10–12 Years in Ningxia Between 2019 and 2024

Background: This study aimed to examine trends in physical fitness among 10–12-year-old children in Ningxia, China, from 2019 to 2024 and to investigate associations between dietary behaviors and physical fitness outcomes using repeated cross-sectional data from the National Student Physical Fitness and Health Survey. Methods: This repeated cross-sectional study included 3970 children aged 10–12 years from Ningxia, China (1960 boys and 2010 girls), based on data from the National Student Physical Fitness and Health Survey conducted in 2019 and 2024. Physical fitness indicators and dietary behaviors (breakfast consumption, egg intake, milk intake, and sugar-sweetened beverage consumption) were assessed using standardized assessments and questionnaires. Sex-stratified t-tests and multivariable linear regression models were performed to examine temporal changes and associations between dietary behaviors and physical fitness outcomes, adjusting for age, BMI, survey year, physical activity, and sleep duration. Results: From 2019 to 2024, both boys and girls showed improvements in multiple physical fitness indicators, including lung capacity, muscular endurance, and speed–agility performance, accompanied by increases in BMI. Adjusted analyses showed modest associations between dietary behaviors and specific fitness outcomes. Egg and breakfast consumption were associated with some measures of muscular endurance, whereas sugary beverage consumption showed associations with several fitness indicators, particularly among girls. Conclusion: Children in Ningxia experienced improvements in physical fitness from 2019 to 2024, alongside changes in body mass status. The observed associations between dietary behaviors and fitness outcomes highlight the potential relevance of modifiable lifestyle factors during late childhood. Integrated school-based strategies combining physical activity promotion, healthy dietary behaviors, and weight monitoring may support healthy development in this population.