{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T21:08:13Z","timestamp":1792789693182,"version":"4.5.0"},"reference-count":37,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T00:00:00Z","timestamp":1789689600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Steno Diabetes Center Copenhagen","id":[{"id":"https:\/\/ror.org\/03gqzdg87","id-type":"ROR","asserted-by":"crossref"}]},{"id":[{"id":"https:\/\/ror.org\/03gqzdg87","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Metabolites"],"abstract":"<jats:p>Purpose: To characterize plasma metabolomic responses to maximal exercise and their associations with cardiorespiratory fitness (CRF) in adults with type 1 diabetes. Methods: In this exploratory pooled secondary analysis, 21 adults (67% female; age, 51.6 \u00b1 13.2 years; HbA1c, 67.5 \u00b1 7.0 mmol\/mol) completed a cycle-ergometer test to exhaustion; metabolomic data were available for 20. Plasma collected at rest, anaerobic threshold (AT), peak exercise, and recovery underwent targeted and untargeted gas chromatography\u2013mass spectrometry profiling. Peak oxygen uptake (V\u0307O2peak) quantified CRF. Linear mixed-effects models adjusted for age, sex, HbA1c, and diabetes duration. Results: At the AT, L-(+)-lactic acid and 2-hydroxyisobutyric acid increased relative to rest (both q \u2264 0.010). Peak exercise produced changes in glycolytic, tricarboxylic acid (TCA)-cycle, and purine metabolites, with enrichment of the TCA cycle and nucleotide metabolism. TCA-cycle enrichment persisted during recovery. In exploratory interaction analyses, higher V\u0307O2peak was associated with increases in L-(+)-lactic acid at AT (\u03b2 = 0.032, q = 0.040) and peak exercise (\u03b2 = 0.031, q = 0.024), and in malic acid at peak exercise (\u03b2 = 0.063, q = 0.010) and recovery (\u03b2 = 0.061, q = 0.015). Conclusions: These preliminary findings suggest the presence of intensity-dependent and fitness-associated metabolic responses to exercise in adults with type 1 diabetes. Given the small sample size, particularly for interaction analyses, these findings require confirmation in larger independent cohorts.<\/jats:p>","DOI":"10.3390\/metabo16090687","type":"journal-article","created":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T11:09:35Z","timestamp":1790075375000},"page":"687","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Exercise Metabolomics Reveals Intensity-Dependent Metabolic Responses Associated with Cardiorespiratory Fitness in Adults with Type 1 Diabetes"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6971-611X","authenticated-orcid":false,"given":"Olivia M.","family":"McCarthy","sequence":"first","affiliation":[{"name":"Copenhagen University Hospital, Steno Diabetes Center Copenhagen, Borgmester Ib Juuls Vej 83, 2730 Herlev, Denmark"},{"name":"Applied Sport, Technology, Exercise and Medicine Research Centre, Faculty of Science and Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Clara","family":"Sol\u00e0","sequence":"additional","affiliation":[{"name":"Copenhagen University Hospital, Steno Diabetes Center Copenhagen, Borgmester Ib Juuls Vej 83, 2730 Herlev, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Chloe","family":"Nicholas","sequence":"additional","affiliation":[{"name":"Copenhagen University Hospital, Steno Diabetes Center Copenhagen, Borgmester Ib Juuls Vej 83, 2730 Herlev, Denmark"},{"name":"Applied Sport, Technology, Exercise and Medicine Research Centre, Faculty of Science and Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, 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Denmark"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6968-6675","authenticated-orcid":false,"given":"Signe","family":"Schmidt","sequence":"additional","affiliation":[{"name":"Copenhagen University Hospital, Steno Diabetes Center Copenhagen, Borgmester Ib Juuls Vej 83, 2730 Herlev, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1620-8271","authenticated-orcid":false,"given":"Kirsten","family":"N\u00f8rgaard","sequence":"additional","affiliation":[{"name":"Copenhagen University Hospital, Steno Diabetes Center Copenhagen, Borgmester Ib Juuls Vej 83, 2730 Herlev, Denmark"},{"name":"Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6986-6449","authenticated-orcid":false,"given":"Richard M.","family":"Bracken","sequence":"additional","affiliation":[{"name":"Applied Sport, Technology, Exercise and Medicine Research Centre, Faculty of Science and Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, UK"},{"name":"Health Technology and Solutions Interdisciplinary Research Institute, Faculty of Science and Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, 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