{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,3]],"date-time":"2026-07-03T05:16:39Z","timestamp":1783055799075,"version":"3.54.6"},"reference-count":18,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,3]],"date-time":"2026-07-03T00:00:00Z","timestamp":1783036800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"\n Background<\/jats:title>\n The increasing prevalence of childhood obesity has made Body Mass Index (BMI) a crucial indicator for assessing children\u2019s physical health. Despite extensive research, the correlation between BMI and physical fitness among China\u2019s ethnically diverse youth remains poorly understood. This study investigates the associations between BMI and physical fitness indicators among primary school students in Sichuan Province, with particular attention to differences by gender, ethnicity, and age.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n The study analyzed physical fitness data from 36,092 primary school students aged 7\u201312 in Sichuan Province. Multivariate analysis of variance, correlation analysis, and hierarchical multiple regression analysis were employed to examine the associations between BMI and physical fitness indicators. Because data on several potential confounders, including diet, socioeconomic status, physical activity, and sleep, were unavailable, these variables were not included in the adjusted models.<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n The study revealed significant differences in BMI across different ethnicities, genders, and age groups. Han students had an average BMI of 17.07, which was significantly higher than the Yi students\u2019 average of 16.90 (\n F<\/jats:italic>\n \u202f=\u202f31.942,\n p<\/jats:italic>\n \u202f&lt;\u202f0.001); boys had an average BMI of 17.18, significantly higher than girls\u2019 average of 16.85 (\n F<\/jats:italic>\n \u202f=\u202f131.733,\n p<\/jats:italic>\n \u202f&lt;\u202f0.001); BMI increased significantly with age, with the 12-year-old group having the highest average (\n M<\/jats:italic>\n \u202f=\u202f18.08). BMI was negatively correlated with 50-meter run performance (\n r<\/jats:italic>\n \u202f=\u202f\u22120.266,\n p<\/jats:italic>\n \u202f&lt;\u202f0.01) and lung capacity (\n r<\/jats:italic>\n \u202f=\u202f\u22120.186,\n p<\/jats:italic>\n \u202f&lt;\u202f0.01). Hierarchical regression analysis showed that several demographic variables, physical fitness indicators, and interaction terms were statistically associated with BMI; however, most effect sizes were small, and the final model explained only a modest proportion of BMI variance (\n R<\/jats:italic>\n 2<\/jats:sup>\n \u202f=\u202f0.110).\n <\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n BMI in primary school students in Sichuan Province was significantly associated with gender, ethnicity, age, and multiple physical fitness indicators. However, because several potential confounding variables were not adjusted for, these findings should be interpreted cautiously as observational associations. The findings provide context-specific evidence that may inform future hypothesis-driven research and regionally targeted public health planning; however, given the generally small effect sizes, their practical significance at the individual level may be limited.<\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fmed.2026.1807499","type":"journal-article","created":{"date-parts":[[2026,7,3]],"date-time":"2026-07-03T04:21:57Z","timestamp":1783052517000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Hierarchical regression analysis of physical fitness and BMI in primary school students in Sichuan Province"],"prefix":"10.3389","volume":"13","author":[{"given":"Defa","family":"Zhang","sequence":"first","affiliation":[{"name":"School of Physical Education, Wuxi Taihu University","place":["Wuxi, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wennan","family":"Zhao","sequence":"additional","affiliation":[{"name":"School of Physical Education, Yanshan University","place":["Qinhuangdao, Hebei, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jingtao","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Physical Education, Leshan Normal University","place":["Leshan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Hu","sequence":"additional","affiliation":[{"name":"School of Physical Education, Leshan Normal University","place":["Leshan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinjuan","family":"Zhao","sequence":"additional","affiliation":[{"name":"School of Physical Education, Leshan Normal University","place":["Leshan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,3]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"4342","DOI":"10.3390\/nu15204342","article-title":"Non-traditional cardiovascular risk factors in adolescents with obesity and metabolic syndrome may predict future cardiovascular disease","volume":"15","author":"Tragomalou","year":"2023","journal-title":"Nutrients"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"863","DOI":"10.1016\/j.jsams.2024.07.013","article-title":"The associations between organized sport participation and physical fitness and weight status development during adolescence","volume":"27","author":"Kolunsarka","year":"2024","journal-title":"J Sci Med Sport"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"105151","DOI":"10.1016\/j.landurbplan.2024.105151","article-title":"Comparison of the impact of school environment on Body Mass Index, physical fitness, and mental health among Chinese adolescents: correlations, risk factors, intermediary effects","volume":"251","author":"Lun","year":"2024","journal-title":"Landsc Urban Plan"},{"key":"ref4","doi-asserted-by":"publisher","first-page":"Article 346","DOI":"10.1186\/s12887-024-04796-x","article-title":"Are physical activity and\/or adherence to the Mediterranean diet determinants of the changes found in kinanthropometric variables, body composition and physical fitness in adolescents?","volume":"24","author":"Mateo-Orcajada","year":"2024","journal-title":"BMC Pediatr"},{"key":"ref5","doi-asserted-by":"publisher","first-page":"396","DOI":"10.1016\/j.jand.2024.07.164","article-title":"Diet quality of Midwest adolescents and young adults with intellectual disabilities and overweight\/obesity differs by diagnosis but not by weight category","volume":"125","author":"Bodde","year":"2024","journal-title":"J Acad Nutr Diet"},{"key":"ref6","doi-asserted-by":"publisher","first-page":"Article 1664","DOI":"10.3390\/children10101664","article-title":"Anthropometric characteristics and weight status of early adolescents (aged 12\u201314) in Montenegro; 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