Effects of body mass index changes on body composition and physical fitness in overweight Korean adults: a sex-stratified path-analytic description of exercise prescription characteristics

Effects of body mass index changes on body composition and physical fitness in overweight Korean adults: a sex-stratified path-analytic description of exercise prescription characteristics | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effects of body mass index changes on body composition and physical fitness in overweight Korean adults: a sex-stratified path-analytic description of exercise prescription characteristics Jae-Il Choi, Yong-Kyun Jeon, Jeong-Yeop Shin, Won-Je Cho This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9511401/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Overweight is a growing public-health burden in Korean adults. Large-scale evidence on how exercise prescription characteristics statistically pattern through body mass index (BMI) change to influence body composition and fitness, and whether these patterns differ by sex, remains limited. Methods From 1,199,471 National Fitness Award Program records (January 2022–December 2025), 12,980 overweight adults aged 19–64 years (10,173 men, 2,807 women) with paired measurements 30–365 days apart were categorized by quartiles of percentage BMI change. Repeated-measures ANCOVA and path-analytic models with BMI change as an intermediate variable (lavaan) were fitted; the principal interpretive focus was on BMI-independent fitness outcomes. Bootstrap 95% CIs (5,000 BCa resamples) and Benjamini–Hochberg FDR correction were applied. Analyses were sex-stratified, with formal sex × Time × Group tests and seven pre-specified sensitivity analyses. Results Among BMI-independent fitness outcomes, Time × Group interactions were largest for step-test VO₂max (partial η² [ηp²] = .021), shuttle-run VO₂max (.017), and relative grip strength (.011). BMI change was robustly associated with all fitness outcomes (FDR-adjusted p < .001). In men, aerobic prescriptions showed direct associations with flexibility (c₂′ = +0.361) and power (+ 1.253), and an indirect association with step-test VO₂max via BMI (a₂·b = − 0.097). In women, the count of prescribed items (n_total) was indirectly associated with step-test VO₂max (a₃·b = + 0.021, 95% CI [+ 0.007, + 0.036]) and blood pressure; direct type associations were not detected, partly reflecting limited power. Sex × Time × Group tests confirmed that the cardiorespiratory ηp² sex difference was significant for shuttle-run VO₂max (FDR-adjusted p = .038) but borderline for step-test VO₂max (FDR-adjusted p = .087). Relative grip strength improved in BMI-decreased and declined in BMI-increased groups despite comparable absolute grip gains, identifying it as a more sensitive functional indicator. Conclusions Path-analytic associations between prescription characteristics and fitness change, indexed through BMI change, followed sex-specific profiles: descriptively type-indexed in men and count-indexed in women (interpretation is hypothesis-generating and associative rather than causal). These observational findings are hypothesis-generating for sex-specific randomized trials. Relative grip strength is recommended as a functional fitness indicator in overweight populations. overweight body mass index exercise prescription body composition physical fitness path-analytic description sex differences National Fitness Award Program bootstrap Korean adults Figures Figure 1 Figure 2 Full Text Additional Declarations No competing interests reported. Tables 1 to 13 are available in the Supplementary Files section. Supplementary Files TablesVer.2.docx SupplementaryTablesVer.2.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9511401","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":631610415,"identity":"c809ee25-3820-4800-a2a0-1589e79f3888","order_by":0,"name":"Jae-Il Choi","email":"","orcid":"","institution":"Dankook University","correspondingAuthor":false,"prefix":"","firstName":"Jae-Il","middleName":"","lastName":"Choi","suffix":""},{"id":631610417,"identity":"40910beb-f011-47dd-adc5-ee068145448f","order_by":1,"name":"Yong-Kyun Jeon","email":"","orcid":"","institution":"Dankook 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overweight Korean adults: a sex-stratified path-analytic description of exercise prescription characteristics","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"overweight, body mass index, exercise prescription, body composition, physical fitness, path-analytic description, sex differences, National Fitness Award Program, bootstrap, Korean adults","lastPublishedDoi":"10.21203/rs.3.rs-9511401/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9511401/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eOverweight is a growing public-health burden in Korean adults. Large-scale evidence on how exercise prescription characteristics statistically pattern through body mass index (BMI) change to influence body composition and fitness, and whether these patterns differ by sex, remains limited.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eFrom 1,199,471 National Fitness Award Program records (January 2022\u0026ndash;December 2025), 12,980 overweight adults aged 19\u0026ndash;64 years (10,173 men, 2,807 women) with paired measurements 30\u0026ndash;365 days apart were categorized by quartiles of percentage BMI change. Repeated-measures ANCOVA and path-analytic models with BMI change as an intermediate variable (lavaan) were fitted; the principal interpretive focus was on BMI-independent fitness outcomes. Bootstrap 95% CIs (5,000 BCa resamples) and Benjamini\u0026ndash;Hochberg FDR correction were applied. Analyses were sex-stratified, with formal sex \u0026times; Time \u0026times; Group tests and seven pre-specified sensitivity analyses.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAmong BMI-independent fitness outcomes, Time \u0026times; Group interactions were largest for step-test VO₂max (partial η\u0026sup2; [ηp\u0026sup2;] = .021), shuttle-run VO₂max (.017), and relative grip strength (.011). BMI change was robustly associated with all fitness outcomes (FDR-adjusted p \u0026lt; .001). In men, aerobic prescriptions showed direct associations with flexibility (c₂\u0026prime; = +0.361) and power (+\u0026thinsp;1.253), and an indirect association with step-test VO₂max via BMI (a₂\u0026middot;b\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.097). In women, the count of prescribed items (n_total) was indirectly associated with step-test VO₂max (a₃\u0026middot;b\u0026thinsp;=\u0026thinsp;+\u0026thinsp;0.021, 95% CI [+\u0026thinsp;0.007, +\u0026thinsp;0.036]) and blood pressure; direct type associations were not detected, partly reflecting limited power. Sex \u0026times; Time \u0026times; Group tests confirmed that the cardiorespiratory ηp\u0026sup2; sex difference was significant for shuttle-run VO₂max (FDR-adjusted p = .038) but borderline for step-test VO₂max (FDR-adjusted p = .087). Relative grip strength improved in BMI-decreased and declined in BMI-increased groups despite comparable absolute grip gains, identifying it as a more sensitive functional indicator.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003ePath-analytic associations between prescription characteristics and fitness change, indexed through BMI change, followed sex-specific profiles: descriptively type-indexed in men and count-indexed in women (interpretation is hypothesis-generating and associative rather than causal). These observational findings are hypothesis-generating for sex-specific randomized trials. Relative grip strength is recommended as a functional fitness indicator in overweight populations.\u003c/p\u003e","manuscriptTitle":"Effects of body mass index changes on body composition and physical fitness in overweight Korean adults: a sex-stratified path-analytic description of exercise prescription characteristics","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-30 10:02:41","doi":"10.21203/rs.3.rs-9511401/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"51431d0c-90bf-4fc5-88dd-1dee4cee16e5","owner":[],"postedDate":"April 30th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-30T10:02:50+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-30 10:02:41","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9511401","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9511401","identity":"rs-9511401","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}