{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T21:19:10Z","timestamp":1792790350817,"version":"4.5.0"},"posted":{"date-parts":[[2026,9,22]]},"group-title":"Physiology","reference-count":19,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T00:00:00Z","timestamp":1790035200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"name":"Arthritis Research UK","award":["22569"],"award-info":[{"award-number":["22569"]}],"id":[{"id":"https:\/\/ror.org\/03phf2w66","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,9,22]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  Age-related skeletal muscle atrophy differs between upper and lower body muscles and may also differ between lower limb muscles, but these muscle-specific patterns remain poorly characterised. We acquired axial 3T magnetic resonance images from sex-balanced samples of thirty young (24\u00b14 years) and thirty older adults (73\u00b14 years). Muscle volume of seventeen lower limb muscles\/compartments was quantified using manual segmentation and expressed as absolute volume, relative to body mass, and as a percentage of total muscle volume. Absolute muscle volume was lower in older adults in 13 out of 17 muscles compared to young, with substantial heterogeneity in the effect sizes (\n                  <jats:italic>d<\/jats:italic>\n                  =0.01-3.36). Age group \u00d7 muscle interaction contrasts revealed muscle-specific age-related differences in volume. Three of the quadriceps muscles demonstrated greater age-related atrophy compared to several other muscles (e.g. vastus lateralis differing from 14 of the other 16 muscles;\n                  <jats:italic>d<\/jats:italic>\n                  \u22651.54). Conversely, the anterior and deep posterior compartments of the shank and biceps femoris short head showed significantly smaller age-related atrophy than several other muscles. These interaction effects were exacerbated when expressed in relative terms. Consequently, three of four shank compartments, gluteus maximus and adductor magnus represented a greater proportion of total muscle volume in older adults, whereas the vastus lateralis, vastus intermedius, rectus femoris, semitendinosus, gracilis, and iliopsoas contributed a smaller proportion in older adults. These findings highlight the variability in age-related leg muscle atrophy in a large mixed sex cohort, resulting in a redistribution of muscle volume in the lower limb.\n                <\/jats:p>","DOI":"10.64898\/2026.09.15.751873","type":"posted-content","created":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T20:15:20Z","timestamp":1790108120000},"source":"Crossref","is-referenced-by-count":0,"title":["The heterogeneity of age-related muscle atrophy of lower limb muscles"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-4697-0945","authenticated-orcid":false,"given":"Christopher D","family":"Connelly","sequence":"first","affiliation":[{"name":"School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3678-6044","authenticated-orcid":false,"given":"Jonathan P","family":"Folland","sequence":"additional","affiliation":[{"name":"School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom"},{"name":"National Institute for Health and Care Research (NIHR) Leicester Biomedical Research Centre, Leicester, LE3 9QP, Leicestershire, United Kingdom"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7804-4631","authenticated-orcid":false,"given":"Mathew","family":"Piasecki","sequence":"additional","affiliation":[{"name":"Centre of Metabolism, Ageing & Physiology (COMAP), National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0118-1216","authenticated-orcid":false,"given":"Jakob","family":"\u0160karabot","sequence":"additional","affiliation":[{"name":"School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026092501350448000_2026.09.15.751873v1.1","doi-asserted-by":"publisher","DOI":"10.1002\/jcsm.12238"},{"key":"2026092501350448000_2026.09.15.751873v1.2","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00768.2022"},{"key":"2026092501350448000_2026.09.15.751873v1.3","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00769.2022"},{"key":"2026092501350448000_2026.09.15.751873v1.4","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.2000.89.1.81"},{"key":"2026092501350448000_2026.09.15.751873v1.5","first-page":"320","article-title":"Comparison of MRI and DXA to measure muscle size and age-related atrophy in thigh muscles","volume":"13","year":"2013","journal-title":"Journal of Musculoskeletal & Neuronal Interactions"},{"key":"2026092501350448000_2026.09.15.751873v1.6","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2474-15-216"},{"key":"2026092501350448000_2026.09.15.751873v1.7","doi-asserted-by":"publisher","DOI":"10.1016\/j.exger.2023.112159"},{"key":"2026092501350448000_2026.09.15.751873v1.8","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00009.2023"},{"key":"2026092501350448000_2026.09.15.751873v1.9","doi-asserted-by":"publisher","DOI":"10.1249\/01.MSS.0000078924.61453.FB"},{"key":"2026092501350448000_2026.09.15.751873v1.10","doi-asserted-by":"publisher","DOI":"10.1093\/gerona\/56.3.M146"},{"key":"2026092501350448000_2026.09.15.751873v1.11","doi-asserted-by":"publisher","DOI":"10.1101\/2025.01.06.25319958"},{"key":"2026092501350448000_2026.09.15.751873v1.12","unstructured":"Lenth R , Singmann H , Love J , Buerkner P , Herve M. 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