Physiological responses during a maximal breath-hold in a world champion freediver

Physiological responses during a maximal breath-hold in a world champion freediver | 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 Case Report Physiological responses during a maximal breath-hold in a world champion freediver Gillian Schockaert, Sofie Engelborghs, Niels Bochanen, Rafael Machado Tironi, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8978491/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 Few studies have described physiological and cardiac rhythm responses to maximal voluntary breath-holding in elite freedivers. This case study presents minute ventilation, PETO 2 , PETCO 2 , involuntary breathing movements (IBMs; surface electromyography), SpO 2 , muscle and cerebral oxygenation (near-infrared spectroscopy), and cardiac rhythm changes (electrocardiogram) before, during, and after a dry, maximal, voluntary breath-hold in a world champion freediver. Glossopharyngeal insufflation prior to the breath-hold increased forced vital capacity from 6.92 L (138% predicted) to 9.04 L (180% predicted). Compared to resting end-tidal gas pressures, the breathe-up in preparation of the breath-hold increased PETO 2 (108 mmHg to 135 mmHg) and decreased PETCO 2 (36 mmHg to 21 mmHg). The breath-hold was 06’07” in duration, of which 02’20” was spent in the easy-going phase and 03’47” in the struggle phase – the latter encompassing a total of 48 IBMs. Throughout the breath-hold, PETO 2 decreased to 38 mmHg and PETCO 2 increased to 65 mmHg. SpO 2 decreased from 97% to 73%. Muscle oxygenation decreased from 50% to 22%, whereas cerebral oxygenation remained relatively stable until the final ∼20 s of the breath-hold (∼68% to ∼62%). Heart rate variability-based markers of autonomic cardiac activity decreased during the easy-going phase, increased during the struggle phase, and normalized after. Asymptomatic bradycardia with competition between sinus bradycardia and junctional rhythm and (supra)ventricular extrasystoles manifested throughout the struggle phase and resolved after breath-hold cessation. This report of a world champion freediver shows that a long voluntary breath-hold induced transient asymptomatic cardiac arrhythmias, likely linked to the physiological stress of extreme voluntary breath-holding. Sports Medicine and Kinesiology Breath-hold Mammalian dive response Hypoxia Arrhythmia Case report Full Text Additional Declarations The authors declare no competing interests. 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-8978491","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":597603362,"identity":"7fe78309-e6f0-476b-b621-5107f6378784","order_by":0,"name":"Gillian Schockaert","email":"","orcid":"https://orcid.org/0009-0003-9936-9616","institution":"KU Leuven","correspondingAuthor":false,"prefix":"","firstName":"Gillian","middleName":"","lastName":"Schockaert","suffix":""},{"id":597603363,"identity":"cbb9a1d9-db03-4a31-87ca-a7135c15bcdd","order_by":1,"name":"Sofie Engelborghs","email":"","orcid":"","institution":"KU 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cardiac rhythm responses to maximal voluntary breath-holding in elite freedivers.\u003c/p\u003e\n\u003cp\u003eThis case study presents minute ventilation, PETO\u003csub\u003e2\u003c/sub\u003e, PETCO\u003csub\u003e2\u003c/sub\u003e, involuntary breathing movements (IBMs; surface electromyography), SpO\u003csub\u003e2\u003c/sub\u003e, muscle and cerebral oxygenation (near-infrared spectroscopy), and cardiac rhythm changes (electrocardiogram) before, during, and after a dry, maximal, voluntary breath-hold in a world champion freediver.\u003c/p\u003e\n\u003cp\u003eGlossopharyngeal insufflation prior to the breath-hold increased forced vital capacity from 6.92 L (138% predicted) to 9.04 L (180% predicted). Compared to resting end-tidal gas pressures, the breathe-up in preparation of the breath-hold increased PETO\u003csub\u003e2\u003c/sub\u003e (108 mmHg to 135 mmHg) and decreased PETCO\u003csub\u003e2\u003c/sub\u003e (36 mmHg to 21 mmHg). The breath-hold was 06’07” in duration, of which 02’20” was spent in the easy-going phase and 03’47” in the struggle phase – the latter encompassing a total of 48 IBMs. Throughout the breath-hold, PETO\u003csub\u003e2\u003c/sub\u003e decreased to 38 mmHg and PETCO\u003csub\u003e2\u003c/sub\u003e increased to 65 mmHg. SpO\u003csub\u003e2\u003c/sub\u003e decreased from 97% to 73%. Muscle oxygenation decreased from 50% to 22%, whereas cerebral oxygenation remained relatively stable until the final ∼20 s of the breath-hold (∼68% to ∼62%). Heart rate variability-based markers of autonomic cardiac activity decreased during the easy-going phase, increased during the struggle phase, and normalized after. Asymptomatic bradycardia with competition between sinus bradycardia and junctional rhythm and (supra)ventricular extrasystoles manifested throughout the struggle phase and resolved after breath-hold cessation.\u003c/p\u003e\n\u003cp\u003eThis report of a world champion freediver shows that a long voluntary breath-hold induced transient asymptomatic cardiac arrhythmias, likely linked to the physiological stress of extreme voluntary breath-holding.\u003c/p\u003e","manuscriptTitle":"Physiological responses during a maximal breath-hold in a world champion freediver","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-27 04:02:15","doi":"10.21203/rs.3.rs-8978491/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":"0bc0ce01-dd46-4eae-a8be-6660ed39f1b4","owner":[],"postedDate":"February 27th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":63593628,"name":"Sports Medicine and Kinesiology"}],"tags":[],"updatedAt":"2026-02-27T04:02:15+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-27 04:02:15","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8978491","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8978491","identity":"rs-8978491","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}