Sex-specific patterns of skeletal muscle aging at the L3 level: a quantitative study based on opportunistic CT

Sex-specific patterns of skeletal muscle aging at the L3 level: a quantitative study based on opportunistic CT | 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 Sex-specific patterns of skeletal muscle aging at the L3 level: a quantitative study based on opportunistic CT Deng Xin¹, Ma Huan¹, Guo Xinyi¹, Li Rui¹, Fu Fei¹, Zhao Hui¹, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9064966/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Objective This study utilized opportunistic abdominal CT data to investigate age- and sex-related changes in muscle mass and quality at the third lumbar vertebra (L3) level in males over 50 and postmenopausal females. Methods Clinical and imaging data from 292 hospitalized patients (146 males, 146 females) admitted between July 2019 and July 2022 were retrospectively analyzed. Patients with musculoskeletal or other wasting diseases were excluded. Skeletal muscle area (SMA), skeletal muscle index (SMI), skeletal muscle density (SMD), intramuscular adipose tissue content (IMAC), and intermuscular adipose tissue (IMAT) were measured at the L3 level using Image J software. Sex- and age-stratified analyses were performed to delineate differential aging patterns. Inter-rater reliability was assessed using the intra-class correlation coefficient (ICC). Independent sample t-tests and one-way ANOVA were used for group comparisons, and univariate linear regression to analyze the impact of age. Results Measurements for all muscle parameters demonstrated excellent inter-rater reliability (ICC > 0.75). In males, SMA, SMI, and SMD declined significantly after age 70 (p < 0.05), accompanied by a significant increase in IMAT (p < 0.05). In females, SMD decreased significantly across all postmenopausal age groups (p < 0.05), while IMAT increased markedly after age 60 (p < 0.05). Notably, while the decline in muscle mass was more pronounced in males, the deterioration of muscle quality and fat infiltration occurred earlier and were more severe in females. Regression analysis showed that with each additional year of age, SMA decreased by 0.504 standard units in males vs. 0.267 in females, whereas the decline in SMD was similar between sexes. Conclusions Our findings reveal a sex-dimorphic pattern of skeletal muscle aging: males experience a more rapid loss of muscle mass, while females exhibit an earlier and more pronounced decline in muscle quality, driven by accelerated intermuscular fat infiltration. These insights underscore the need for sex-specific strategies in the assessment and management of sarcopenia and related musculoskeletal aging. opportunistic CT sarcopenia༛myosteatosis༛male / female༛age factors༛body composition Full Text Additional Declarations No competing interests reported. This study was approved by the Ethics Committee of Tianjin Hospital. Given the retrospective nature of the study and the use of anonymized clinical data, the requirement for written informed consent from participants was waived by the ethics committee. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 11 May, 2026 Reviewers agreed at journal 11 May, 2026 Reviewers agreed at journal 17 Apr, 2026 Reviews received at journal 25 Mar, 2026 Reviewers agreed at journal 17 Mar, 2026 Reviewers invited by journal 11 Mar, 2026 Editor invited by journal 11 Mar, 2026 Editor assigned by journal 11 Mar, 2026 Submission checks completed at journal 11 Mar, 2026 First submitted to journal 08 Mar, 2026 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-9064966","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":603832447,"identity":"28676eb3-6ba6-4214-a1d7-7835256da07f","order_by":0,"name":"Deng Xin¹","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Deng","middleName":"","lastName":"Xin¹","suffix":""},{"id":603832451,"identity":"b0b9496c-d66a-44e4-9fe8-6c04ed5e9ba1","order_by":1,"name":"Ma Huan¹","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ma","middleName":"","lastName":"Huan¹","suffix":""},{"id":603832452,"identity":"5d5cac95-1201-414c-9c7c-65fd0925df3a","order_by":2,"name":"Guo Xinyi¹","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Guo","middleName":"","lastName":"Xinyi¹","suffix":""},{"id":603832454,"identity":"3f5edb91-ef39-4f44-8526-9f5d30020a5c","order_by":3,"name":"Li Rui¹","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Li","middleName":"","lastName":"Rui¹","suffix":""},{"id":603832456,"identity":"71ff8b43-f48b-4407-bd0d-5a07553f762a","order_by":4,"name":"Fu Fei¹","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Fu","middleName":"","lastName":"Fei¹","suffix":""},{"id":603832457,"identity":"19aab241-cef1-4e48-bb85-0730b9042a20","order_by":5,"name":"Zhao Hui¹","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Zhao","middleName":"","lastName":"Hui¹","suffix":""},{"id":603832458,"identity":"ab43ce3c-3312-437d-93d0-52517246dc15","order_by":6,"name":"Guo Lin¹","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Guo","middleName":"","lastName":"Lin¹","suffix":""},{"id":603832459,"identity":"15ecd4a2-7e44-4e0a-bb03-6ee27f18e72d","order_by":7,"name":"Wan Yeda¹","email":"","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":false,"prefix":"","firstName":"Wan","middleName":"","lastName":"Yeda¹","suffix":""},{"id":603832460,"identity":"d41c5468-536f-41a5-93cc-1eff0f1fa96c","order_by":8,"name":"He Zhen¹","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAmUlEQVRIiWNgGAWjYBACAwYGZoYPBjZ2pGlhnFGQlkyaFmaeD4cYG4jWYs5/+LCxjcEBZgb2w0c3EKXFsuFYcnKOwR0+Bp60tBvEOexgj/HhHINnzAwSPGZEajnMY3zYwuAwYwPxWo7xGCczkKblDFuyYY9BWjIb8X45f/iwxI8/Nnb87IePEacFDthIUz4KRsEoGAWjAC8AADi0K8SM7LOLAAAAAElFTkSuQmCC","orcid":"","institution":"Tianjin Hospital","correspondingAuthor":true,"prefix":"","firstName":"He","middleName":"","lastName":"Zhen¹","suffix":""}],"badges":[],"createdAt":"2026-03-08 14:40:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9064966/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9064966/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104383595,"identity":"d6a8af7d-9f96-4683-b817-2d9382b8a99a","added_by":"auto","created_at":"2026-03-11 08:12:34","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":937218,"visible":true,"origin":"","legend":"","description":"","filename":"38.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9064966/v1_covered_8463ce6e-8140-4ee8-813d-141cbb2ca3c2.pdf"}],"financialInterests":"\u003cp\u003eNo competing interests reported.\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Ethics Committee of Tianjin Hospital. Given the retrospective nature of the study and the use of anonymized clinical data, the requirement for written informed consent from participants was waived by the ethics committee.\u003c/p\u003e","formattedTitle":"Sex-specific patterns of skeletal muscle aging at the L3 level: a quantitative study based on opportunistic CT","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"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":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"opportunistic CT, sarcopenia༛myosteatosis༛male / female༛age factors༛body composition","lastPublishedDoi":"10.21203/rs.3.rs-9064966/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9064966/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eThis study utilized opportunistic abdominal CT data to investigate age- and sex-related changes in muscle mass and quality at the third lumbar vertebra (L3) level in males over 50 and postmenopausal females.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eClinical and imaging data from 292 hospitalized patients (146 males, 146 females) admitted between July 2019 and July 2022 were retrospectively analyzed. Patients with musculoskeletal or other wasting diseases were excluded. Skeletal muscle area (SMA), skeletal muscle index (SMI), skeletal muscle density (SMD), intramuscular adipose tissue content (IMAC), and intermuscular adipose tissue (IMAT) were measured at the L3 level using Image J software. Sex- and age-stratified analyses were performed to delineate differential aging patterns. Inter-rater reliability was assessed using the intra-class correlation coefficient (ICC). Independent sample t-tests and one-way ANOVA were used for group comparisons, and univariate linear regression to analyze the impact of age.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eMeasurements for all muscle parameters demonstrated excellent inter-rater reliability (ICC\u0026thinsp;\u0026gt;\u0026thinsp;0.75). In males, SMA, SMI, and SMD declined significantly after age 70 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), accompanied by a significant increase in IMAT (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In females, SMD decreased significantly across all postmenopausal age groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), while IMAT increased markedly after age 60 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Notably, while the decline in muscle mass was more pronounced in males, the deterioration of muscle quality and fat infiltration occurred earlier and were more severe in females. Regression analysis showed that with each additional year of age, SMA decreased by 0.504 standard units in males vs. 0.267 in females, whereas the decline in SMD was similar between sexes.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eOur findings reveal a sex-dimorphic pattern of skeletal muscle aging: males experience a more rapid loss of muscle mass, while females exhibit an earlier and more pronounced decline in muscle quality, driven by accelerated intermuscular fat infiltration. These insights underscore the need for sex-specific strategies in the assessment and management of sarcopenia and related musculoskeletal aging.\u003c/p\u003e","manuscriptTitle":"Sex-specific patterns of skeletal muscle aging at the L3 level: a quantitative study based on opportunistic CT","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-11 08:09:30","doi":"10.21203/rs.3.rs-9064966/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"123825216906610502796851966332372712188","date":"2026-05-11T13:42:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"66564680927915331035953241718934318254","date":"2026-05-11T10:14:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"209594556908728464841945470414425391903","date":"2026-04-17T14:32:09+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-25T13:48:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"223224971788583678029961248675549900232","date":"2026-03-17T06:54:36+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-11T20:58:43+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-11T13:00:20+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-11T04:20:02+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-11T04:19:04+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2026-03-08T14:31:16+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f34af460-cc32-4c5e-9669-d5c52c588312","owner":[],"postedDate":"March 11th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"123825216906610502796851966332372712188","date":"2026-05-11T13:42:36+00:00","index":192,"fulltext":""},{"type":"reviewerAgreed","content":"66564680927915331035953241718934318254","date":"2026-05-11T10:14:10+00:00","index":191,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-11T21:08:23+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-11 08:09:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9064966","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9064966","identity":"rs-9064966","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}