{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T01:23:33Z","timestamp":1787016213014,"version":"build-2736575974"},"reference-count":24,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2022,11,30]],"date-time":"2022-11-30T00:00:00Z","timestamp":1669766400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["physoc.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Experimental Physiology"],"published-print":{"date-parts":[[2023,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    Repeated maximal breath\u2010holds have been demonstrated to induce bradycardia, increase haematocrit and haemoglobin and prolong subsequent breath\u2010hold duration by 20%. Freedivers use non\u2010maximal breath\u2010hold techniques (BHTs) to improve breath\u2010hold duration. The aim of this study was to investigate the cardiorespiratory and haematological responses to various BHTs. Ten healthy men (34.5\u00a0\u00b1\u00a01.9 years) attended five randomized experimental trials and performed a 40\u00a0min period of quiet rest or one of three BHTs followed by a maximal breath\u2010hold challenge during facial immersion in water at 30 or 10\u00b0C. Cardiovascular and respiratory parameters were measured continuously using finger plethysmography and breath\u2010by\u2010breath gas analysis, respectively, and venous blood samples were collected throughout. Facial immersion in cold water caused marked bradycardia (74.1 vs. 50.2\u00a0beats\/min after 40 s) but did not increase breath\u2010hold duration compared with warm water control conditions. Facial immersion breath\u2010hold duration was 30.8\u201343.3% greater than the control duration when preceded by BHTs that involved repeated breath\u2010holds of constant duration (\n                    <jats:italic>P<\/jats:italic>\n                    \u00a0=\u00a00.021), increasing duration (\n                    <jats:italic>P<\/jats:italic>\n                    \u00a0&lt;\u00a00.001) or increasing frequency (\n                    <jats:italic>P<\/jats:italic>\n                    \u00a0&lt;\u00a00.001), with no difference observed between BHTs. The increased duration of apnoea across all three BHT protocols was associated with a 6.8% increase in end\u2010tidal O\n                    <jats:sub>2<\/jats:sub>\n                    and a 13.1% decrease in end\u2010tidal CO\n                    <jats:sub>2<\/jats:sub>\n                    immediately before facial immersion. There were no differences in blood pressure, cardiac output, heart rate, haematocrit or haemoglobin between each BHT and control conditions (\n                    <jats:italic>P<\/jats:italic>\n                    \u00a0&gt;\u00a00.05). In conclusion, the duration of apnoea can be extended by manipulating blood gases through repeated prior breath\u2010holds, but changes in cardiac output and red blood cell mass do not appear essential.\n                  <\/jats:p>","DOI":"10.1113\/ep090531","type":"journal-article","created":{"date-parts":[[2022,11,30]],"date-time":"2022-11-30T04:43:24Z","timestamp":1669783404000},"page":"50-62","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["The effect of various breath\u2010hold techniques on the cardiorespiratory response to facial immersion in humans"],"prefix":"10.1113","volume":"108","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6838-1020","authenticated-orcid":false,"given":"Matthew J.","family":"Burley","sequence":"first","affiliation":[{"name":"Department of Sport and Health Sciences College of Life and Environmental Sciences University of Exeter  Exeter UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jamie","family":"Blackwell","sequence":"additional","affiliation":[{"name":"Department of Sport and Health Sciences College of Life and Environmental Sciences University of Exeter  Exeter UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3597-8562","authenticated-orcid":false,"given":"Bert","family":"Bond","sequence":"additional","affiliation":[{"name":"Department of Sport and Health Sciences College of Life and Environmental Sciences University of Exeter  Exeter UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1740-6248","authenticated-orcid":false,"given":"Craig","family":"Williams","sequence":"additional","affiliation":[{"name":"Department of Sport and Health Sciences College of Life and Environmental Sciences University of Exeter  Exeter UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6312-5351","authenticated-orcid":false,"given":"Francis B.","family":"Stephens","sequence":"additional","affiliation":[{"name":"Department of Sport and Health Sciences College of Life and Environmental Sciences University of Exeter  Exeter UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2022,11,30]]},"reference":[{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1007\/s004210000317"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00221.2003"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1038\/ajh.2011.106"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00055.2001"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1113\/jphysiol.1986.sp016196"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1172\/JCI101757"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1600-0838.2005.00440.x"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.1186\/s12970-016-0134-y"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1976.41.3.336"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1161\/HYPERTENSIONAHA.108.127530"},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1959.14.5.689"},{"key":"e_1_2_9_13_1","doi-asserted-by":"publisher","DOI":"10.1080\/02640410903121351"},{"issue":"3","key":"e_1_2_9_14_1","first-page":"288","article-title":"End\u2010tidal and arterial carbon dioxide measurements correlate across all levels of physiologic dead space","volume":"55","author":"McSwain S. 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E.","year":"1990","journal-title":"Japanese Journal of Physiology"},{"key":"e_1_2_9_18_1","doi-asserted-by":"publisher","DOI":"10.1007\/s004210050341"},{"key":"e_1_2_9_19_1","doi-asserted-by":"publisher","DOI":"10.1139\/h05-120"},{"issue":"1","key":"e_1_2_9_20_1","first-page":"4","article-title":"Effect of hypercapnia on spleen\u2010related haemoglobin increase during apnea","volume":"42","author":"Richardson M. 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