{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T17:52:25Z","timestamp":1774374745112,"version":"3.50.1"},"reference-count":43,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,1,6]],"date-time":"2025-01-06T00:00:00Z","timestamp":1736121600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005350","name":"Centrum f\u00f6r Idrottsforskning","doi-asserted-by":"publisher","award":["P2023-0120"],"award-info":[{"award-number":["P2023-0120"]}],"id":[{"id":"10.13039\/501100005350","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Physiol."],"abstract":"<jats:sec><jats:title>Background and aim<\/jats:title><jats:p>Hyperventilation before breath-hold diving (freediving) is widely accepted as a risk factor for hypoxic syncope or blackout (BO), but there is no practical way to address it before dives. This study explores the feasibility of using a force sensor to predict end-tidal carbon dioxide (<jats:italic>P<\/jats:italic><jats:sub>ET<\/jats:sub>CO<jats:sub>2<\/jats:sub>) to assess hyperventilation in freedivers.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods and results<\/jats:title><jats:p>Twenty-one freedivers volunteered to participate during two national competitions. The divers were instructed to breathe normally and perform three dry apneas of 1, 2, and 3-min duration at 2-min intervals in a sitting position. Before and after the apneas, <jats:italic>P<\/jats:italic><jats:sub>ET<\/jats:sub>CO<jats:sub>2<\/jats:sub> was recorded. The signal from the force sensor, attached to a chest belt, was used to record the frequency and amplitude of the chest movements, and the product of these values in the 60\u00a0s before the apnea was used to predict <jats:italic>P<\/jats:italic><jats:sub>ET<\/jats:sub>CO<jats:sub>2<\/jats:sub>. The mean <jats:italic>P<\/jats:italic><jats:sub>ET<\/jats:sub>CO<jats:sub>2<\/jats:sub> was below 35\u00a0mmHg before all apneas. The mean amplitude of the signal from the force sensor increased from apnea 1 to apnea 3 (p &amp;lt; 0.001), while the respiratory rate was similar (NS). The product of the respiratory rate and amplitude from the force sensor explained 34% of the variability of the <jats:italic>P<\/jats:italic><jats:sub>ET<\/jats:sub>CO<jats:sub>2<\/jats:sub> in the third apnea.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>This study shows that a force sensor can estimate hyperventilation before static apnea, providing a basis for further research. More studies are needed to confirm its effectiveness in preventing issues. Freedivers may hyperventilate without noticing it, and such a system could improve awareness of this condition. Additional underwater tests are essential to determine whether this system can enhance safety in freediving.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fphys.2024.1498399","type":"journal-article","created":{"date-parts":[[2025,1,6]],"date-time":"2025-01-06T07:03:20Z","timestamp":1736147000000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Toward a hyperventilation detection system in freediving: a proof of concept using force sensor technology"],"prefix":"10.3389","volume":"15","author":[{"given":"Frank","family":"Pernett","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eric","family":"Mulder","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Filip","family":"Johansson","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Arne","family":"Sieber","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ricardo","family":"Bermudez","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marcus","family":"Lossner","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Erika","family":"Schagatay","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2025,1,6]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"30","DOI":"10.1152\/jappl.1963.18.1.30","article-title":"Diaphragm activity during breath holding: factors related to its onset","volume":"18","author":"Agostoni","year":"1963","journal-title":"J. Appl. Physiol."},{"key":"B2","doi-asserted-by":"publisher","first-page":"3231","DOI":"10.1177\/0271678X16686093","article-title":"Hypercapnia is essential to reduce the cerebral oxidative metabolism during extreme apnea in humans","volume":"37","author":"Bain","year":"2017","journal-title":"J. Cereb. Blood Flow Metabolism"},{"key":"B3","doi-asserted-by":"publisher","first-page":"379","DOI":"10.3758\/BF03192707","article-title":"Recommended effect size statistics for repeated measures designs","volume":"37","author":"Bakeman","year":"2005","journal-title":"Behav. Res. Methods"},{"key":"B4","doi-asserted-by":"publisher","first-page":"307","DOI":"10.1016\/s0140-6736(86)90837-8","article-title":"Statistical methods for assessing agreement between two methods of clinical measurement","volume":"327","author":"Bland","year":"1986","journal-title":"Lancet"},{"key":"B5","doi-asserted-by":"publisher","first-page":"1558","DOI":"10.3389\/fphys.2018.01558","article-title":"Arterial blood gas analysis in breath-hold divers at depth","volume":"9","author":"Bosco","year":"2018","journal-title":"Front. Physiol."},{"key":"B6","first-page":"518","article-title":"Fatal and nonfatal drowning outcomes related to dangerous underwater breath-holding behaviors - New York State, 1988-2011","volume":"64","author":"Boyd","year":"2015","journal-title":"MMWR Morb. Mortal. Wkly. Rep."},{"key":"B7","doi-asserted-by":"publisher","first-page":"793","DOI":"10.1136\/jnnp.2009.174425","article-title":"Spontaneous hyperventilation and brain tissue hypoxia in patients with severe brain injury","volume":"81","author":"Carrera","year":"2010","journal-title":"J. Neurol. Neurosurg. Psychiatry"},{"key":"B8","volume-title":"Statistical power analysis for the behavioral sciences","author":"Cohen","year":"1988"},{"key":"B9","doi-asserted-by":"publisher","first-page":"171","DOI":"10.1249\/00005768-197600830-00007","article-title":"Summary of 58 cases of loss of consciousness during underwater swimming and diving","volume":"8","author":"Craig","year":"1976","journal-title":"Med. Sci. Sports"},{"key":"B10","doi-asserted-by":"publisher","first-page":"583","DOI":"10.1152\/jappl.1961.16.4.583","article-title":"Causes of loss of consciousness during underwater swimming","volume":"16","author":"Craig","year":"1961","journal-title":"J. Appl. Physiol."},{"key":"B11","doi-asserted-by":"publisher","first-page":"445","DOI":"10.1001\/JAMA.1955.02960060003002","article-title":"Clinical aspects of glossopharyngeal breathing; report of use by one hundred postpoliomyelitic patients","volume":"158","author":"Dail","year":"1955","journal-title":"J. Am. Med. Assoc."},{"key":"B12","doi-asserted-by":"publisher","first-page":"100103","DOI":"10.1016\/j.resplu.2021.100103","article-title":"An underappreciated cause of ocean-related fatalities: a systematic review on the epidemiology, risk factors, and treatment of snorkelling-related drowning","volume":"6","author":"Dunne","year":"2021","journal-title":"Resusc. Plus"},{"key":"B13","doi-asserted-by":"publisher","first-page":"591","DOI":"10.5694\/j.1326-5377.1999.tb123809.x","article-title":"Snorkelling deaths in Australia, 1987-1996","volume":"171","author":"Edmonds","year":"1999","journal-title":"Med. J. Aus"},{"key":"B14","doi-asserted-by":"publisher","first-page":"794","DOI":"10.1152\/jappl.1991.70.2.794","article-title":"Alveolar gas composition and exchange during deep breath-hold diving and dry breath holds in elite divers","volume":"70","author":"Ferretti","year":"1991","journal-title":"J. Appl. Physiol."},{"key":"B15","doi-asserted-by":"publisher","first-page":"743","DOI":"10.1002\/cphy.c100045","article-title":"Control of breathing during exercise","volume":"2","author":"Forster","year":"2012","journal-title":"Compr. Physiol."},{"key":"B16","doi-asserted-by":"publisher","first-page":"463","DOI":"10.1097\/00005373-199509000-00012","article-title":"Cerebral blood flow and blood volume in response to O2 and CO2 changes in normal humans","volume":"39","author":"Fortune","year":"1995","journal-title":"J. Trauma"},{"key":"B17","doi-asserted-by":"publisher","first-page":"201","DOI":"10.1016\/0034-5687(73)90078-9","article-title":"Hyperventilation, breath holding and alveolar oxygen tensions at the breaking point","volume":"19","author":"Hill","year":"1973","journal-title":"Respir. Physiol."},{"key":"B18","doi-asserted-by":"publisher","first-page":"844","DOI":"10.1152\/japplphysiol.00637.2013","article-title":"Hyperventilation, cerebral perfusion, and syncope","volume":"116","author":"Immink","year":"2014","journal-title":"J. Appl. Physiol."},{"key":"B19","doi-asserted-by":"publisher","first-page":"182","DOI":"10.1055\/S-0043-1771179","article-title":"Comparison of the arterial PaCO2 values and ETCO2 values measured with sidestream capnography in patients with a prediagnosis of COPD exacerbation","volume":"13","author":"\u0130\u015fat","year":"2023","journal-title":"Avicenna J. Med."},{"key":"B20","doi-asserted-by":"publisher","first-page":"663","DOI":"10.5694\/j.1326-5377.2010.tb03673.x","article-title":"Don\u2019t hold your breath: anoxic convulsions from coupled hyperventilation-underwater breath-holding","volume":"192","author":"Kumar","year":"2010","journal-title":"Med. J. Aus"},{"key":"B21","doi-asserted-by":"publisher","first-page":"863","DOI":"10.3389\/fpsyg.2013.00863","article-title":"Calculating and reporting effect sizes to facilitate cumulative science: a practical primer for t-tests and ANOVAs","volume":"4","author":"Lakens","year":"2013","journal-title":"Front. Psychol."},{"key":"B22","doi-asserted-by":"publisher","first-page":"291","DOI":"10.1152\/jappl.1974.37.3.291","article-title":"Physiological and conventional breath hold breaking points","volume":"37","author":"Lin","year":"1974","journal-title":"J. Appl. Physiol."},{"key":"B23","doi-asserted-by":"publisher","first-page":"701","DOI":"10.1007\/s00421-004-1242-y","article-title":"Aggravated hypoxia during breath-holds after prolonged exercise","volume":"93","author":"Lindholm","year":"2005","journal-title":"Eur. J. Appl. Physiol."},{"key":"B24","first-page":"463","article-title":"Alveolar gas composition before and after maximal breath-holds in competitive divers","volume":"33","author":"Lindholm","year":"2006","journal-title":"Undersea Hyperb. Med."},{"key":"B25","doi-asserted-by":"publisher","first-page":"192","DOI":"10.28920\/dhm49.3.192-203","article-title":"Snorkelling and breath-hold diving fatalities in Australia, 2001 to 2013. Demographics, characteristics and chain of events","volume":"49","author":"Lippmann","year":"2019","journal-title":"Diving Hyperb. Med."},{"key":"B26","doi-asserted-by":"publisher","first-page":"230","DOI":"10.5694\/mja11.10988","article-title":"Snorkelling-related deaths in Australia, 1994-2006","volume":"197","author":"Lippmann","year":"2012","journal-title":"Med. J. Aus"},{"key":"B27","doi-asserted-by":"publisher","DOI":"10.31236\/OSF.IO\/8JNBR","article-title":"Features of gas exchange in advanced level freediver during monofin practice in pool","author":"Molchanova","year":"2020","journal-title":"SportRxiv"},{"key":"B28","doi-asserted-by":"publisher","first-page":"4124","DOI":"10.3390\/S21124124","article-title":"Assessing the tidal volume through wearables: a scoping review","volume":"21","author":"Monaco","year":"2021","journal-title":"Sensors (Basel)"},{"key":"B29","doi-asserted-by":"publisher","first-page":"649674","DOI":"10.3389\/fphys.2021.649674","article-title":"First evaluation of a newly constructed underwater pulse oximeter for use in breath-holding activities","volume":"12","author":"Mulder","year":"2021","journal-title":"Front. Physiol."},{"key":"B30","doi-asserted-by":"publisher","first-page":"104","DOI":"10.1055\/s-2003-38401","article-title":"Arterial blood gases during diving in elite apnea divers","volume":"24","author":"Muth","year":"2003","journal-title":"Int. J. Sports Med."},{"key":"B31","first-page":"80","article-title":"Mechanisms of \u201cbuccal pumping\u201d (\u201clung packing\u201d) and its pulmonary effects","volume-title":"24th annual scientific meeting, European underwater baromedical society","author":"\u00d6rnhagen","year":"1998"},{"key":"B32","doi-asserted-by":"publisher","first-page":"100378","DOI":"10.1016\/J.SBSR.2020.100378","article-title":"Design of a low cost, double triangle, piezoelectric sensor for respiratory monitoring applications","volume":"30","author":"Panahi","year":"2020","journal-title":"Sens. Biosensing Res."},{"key":"B33","doi-asserted-by":"publisher","first-page":"1809","DOI":"10.1007\/s00421-023-05202-7","article-title":"Effects of hyperventilation on oxygenation, apnea breaking points, diving response, and spleen contraction during serial static apneas","volume":"123","author":"Pernett","year":"2023","journal-title":"Eur. J. Appl. Physiol."},{"key":"B34","doi-asserted-by":"publisher","first-page":"285","DOI":"10.1152\/jappl.1993.75.1.285","article-title":"Arterial blood gas tensions during breath-hold diving in the Korean ama","volume":"75","author":"Qvist","year":"1993","journal-title":"J. Appl. Physiol."},{"key":"B35","doi-asserted-by":"publisher","first-page":"566","DOI":"10.1161\/01.str.3.5.566","article-title":"Hyperventilation and cerebral blood flow","volume":"3","author":"Raichle","year":"1972","journal-title":"Stroke"},{"key":"B36","doi-asserted-by":"publisher","first-page":"25","DOI":"10.1152\/AJPLEGACY.1964.206.1.25","article-title":"Arterial Pco2 and cerebral hemodynamics","volume":"206","author":"Reivich","year":"1964","journal-title":"Am. J. Physiol."},{"key":"B37","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1007\/BF00262802","article-title":"Effects of water and ambient air temperatures on human diving bradycardia","volume":"73","author":"Schagatay","year":"1996","journal-title":"Eur. J. Appl. Physiol."},{"key":"B38","first-page":"822","article-title":"Breath holding in divers and non-divers-a reappraisal","volume":"69","author":"Schneeberger","year":"1986","journal-title":"S Afr. Med. J."},{"key":"B39","doi-asserted-by":"publisher","first-page":"1490","DOI":"10.1152\/japplphysiol.00111.2021","article-title":"Arterial blood gas measurements during deep open-water breath-hold dives","volume":"130","author":"Scott","year":"2021","journal-title":"J. Appl. Physiol."},{"key":"B40","article-title":"Novel sensor for assessment of involuntary breathing movements (respiratory contractions) during breath-hold diving [poster presentation]","volume-title":"46th annual European underwater and baromedical society conference","author":"Sieber","year":"2022"},{"key":"B41","doi-asserted-by":"publisher","first-page":"399","DOI":"10.1007\/S10877-022-00901-6\/","article-title":"Comparison of mainstream end tidal carbon dioxide on Y-piece side versus patient side of heat and moisture exchanger filters in critically ill adult patients: a prospective observational study","volume":"37","author":"Tamashiro","year":"2023","journal-title":"J. Clin. Monit. Comput."},{"key":"B42","volume-title":"West\u2019s respiratory physiology: the essentials","author":"West","year":"2021"},{"key":"B43","doi-asserted-by":"publisher","first-page":"292","DOI":"10.1002\/PPUL.10260","article-title":"Good estimation of arterial carbon dioxide by end-tidal carbon dioxide monitoring in the neonatal intensive care unit","volume":"35","author":"Wu","year":"2003","journal-title":"Pediatr. Pulmonol."}],"container-title":["Frontiers in Physiology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fphys.2024.1498399\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,1,6]],"date-time":"2025-01-06T07:03:25Z","timestamp":1736147005000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fphys.2024.1498399\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,1,6]]},"references-count":43,"alternative-id":["10.3389\/fphys.2024.1498399"],"URL":"https:\/\/doi.org\/10.3389\/fphys.2024.1498399","relation":{},"ISSN":["1664-042X"],"issn-type":[{"value":"1664-042X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,1,6]]},"article-number":"1498399"}}