{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T05:39:14Z","timestamp":1790314754788,"version":"4.1.0"},"reference-count":40,"publisher":"Wiley","issue":"21","license":[{"start":{"date-parts":[[2023,9,29]],"date-time":"2023-09-29T00:00:00Z","timestamp":1695945600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/501100000038","name":"Natural Sciences and Engineering Research Council of Canada","doi-asserted-by":"publisher","award":["RGPIN\u20102019\u201004615"],"award-info":[{"award-number":["RGPIN\u20102019\u201004615"]}],"id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000038","name":"Natural Sciences and Engineering Research Council of Canada","doi-asserted-by":"publisher","award":["RGPIN\u20102022\u201002977"],"award-info":[{"award-number":["RGPIN\u20102022\u201002977"]}],"id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000196","name":"Canada Foundation for Innovation","doi-asserted-by":"publisher","award":["#38432"],"award-info":[{"award-number":["#38432"]}],"id":[{"id":"10.13039\/501100000196","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["physoc.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["The Journal of Physiology"],"published-print":{"date-parts":[[2023,11]]},"abstract":"Abstract<\/jats:title>Intrathoracic pressure (ITP) swings that permit spontaneous ventilation have physiological implications for the heart. We sought to determine the effect of respiration on cardiac output () during semi\u2010supine cycle exercise using a proportional assist ventilator to minimize ITP changes and lower the work of breathing (W<\/jats:italic>b<\/jats:sub>). Twenty\u2010four participants (12 females) completed three exercise trials at 30%, 60% and 80% peak power (W<\/jats:italic>max<\/jats:sub>) with unloaded (using a proportional assist ventilator, PAV) and spontaneous breathing. Intrathoracic and intraabdominal pressures were measured with balloon catheters placed in the oesophagus and stomach. Left ventricular (LV) volumes and were determined via echocardiography. Heart rate (HR) was measured with electrocardiogram and a customized metabolic cart measured oxygen uptake (). Oesophageal pressure swings decreased from spontaneous to PAV breathing by \u22122.8\u00a0\u00b1\u00a03.1, \u22124.9\u00a0\u00b1\u00a05.7 and \u22128.1\u00a0\u00b1\u00a07.7\u00a0cmH2<\/jats:sub>O at 30%, 60% and 80% W<\/jats:italic>max<\/jats:sub>, respectively (P\u00a0=<\/jats:italic>\u00a00.01). However, the decreases in W<\/jats:italic>b<\/jats:sub> were similar across exercise intensities (27\u00a0\u00b1\u00a042 vs<\/jats:italic>. 35\u00a0\u00b1\u00a024 vs<\/jats:italic>. 41\u00a0\u00b1\u00a022%, respectively, P\u00a0=<\/jats:italic>\u00a00.156). During PAV breathing compared to spontaneous breathing, decreased by \u22121.0\u00a0\u00b1\u00a01.3 vs<\/jats:italic>. \u22121.4\u00a0\u00b1\u00a01.4 vs<\/jats:italic>. \u22121.5\u00a0\u00b1\u00a01.9 l\u00a0min\u22121<\/jats:sup> (all P\u00a0<<\/jats:italic>\u00a00.05) and stroke volume decreased during PAV breathing by \u221211\u00a0\u00b1\u00a012 vs<\/jats:italic>. \u22129\u00a0\u00b1\u00a010 vs<\/jats:italic>. \u22127\u00a0\u00b1\u00a011\u00a0ml from spontaneous breathing at 30%, 60% and 80% W<\/jats:italic>max<\/jats:sub>, respectively (all P\u00a0<<\/jats:italic>\u00a00.05). HR was lower during PAV breathing by \u22125\u00a0\u00b1\u00a04\u00a0beats\u00a0min\u22121<\/jats:sup> at 80% W<\/jats:italic>max<\/jats:sub> (P\u00a0<<\/jats:italic>\u00a00.0001). Oxygen uptake decreased by 100\u00a0ml min\u22121<\/jats:sup> during PAV breathing compared to spontaneous breathing at 80% W<\/jats:italic>max<\/jats:sub> (P\u00a0<<\/jats:italic>\u00a00.0001). Overall, attenuating ITPs mitigated LV preload and ejection, thereby suggesting that the ITPs associated with spontaneous respiration impact cardiac function during exercise.\nimage<\/jats:alt-text><\/jats:graphic><\/jats:boxed-text><\/jats:p><\/jats:sec>Key points<\/jats:title>\nPulmonary ventilation is accomplished by alterations in intrathoracic pressure (ITP), which have physiological implications on the heart and dynamically influence the loading parameters of the heart.<\/jats:p><\/jats:list-item>\nProportional assist ventilation was used to attenuate ITP changes and decrease the work of breathing during exercise to examine its effects on left ventricular (LV) function.<\/jats:p><\/jats:list-item>\nProportional assist ventilation with progressive exercise intensities (30%, 60% and 80% W<\/jats:italic>max<\/jats:sub>) led to reductions in cardiac output at all intensities, primarily through reductions in stroke volume.<\/jats:p><\/jats:list-item>\nDecreases in LV end\u2010diastolic volume (30% and 60% W<\/jats:italic>max<\/jats:sub>) and increases in LV end\u2010systolic volume (80% W<\/jats:italic>max<\/jats:sub>) were responsible for the reduction in stroke volume.<\/jats:p><\/jats:list-item>\nThe relationship between cardiac output and oxygen uptake is disrupted during respiratory muscle unloading.<\/jats:p><\/jats:list-item>\n<\/jats:list><\/jats:p><\/jats:sec>","DOI":"10.1113\/jp285101","type":"journal-article","created":{"date-parts":[[2023,9,29]],"date-time":"2023-09-29T13:32:36Z","timestamp":1695994356000},"page":"4807-4821","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Attenuating intrathoracic pressure swings decreases cardiac output at different intensities of exercise"],"prefix":"10.1113","volume":"601","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0265-254X","authenticated-orcid":false,"given":"Sarah 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of British Columbia Vancouver British Columbia Canada"},{"name":"Department of Cellular and Physiological Science, Faculty of Medicine The University of British Columbia Vancouver British Columbia Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eric J.","family":"St\u00f6hr","sequence":"additional","affiliation":[{"name":"Institute of Sports Science, COR\u2010HELIX Leibniz University Hannover Hannover Germany"},{"name":"Department of Medicine Division of Cardiology Columbia University Irving Medical Center New York NY USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8601-323X","authenticated-orcid":false,"given":"Jason S.","family":"Au","sequence":"additional","affiliation":[{"name":"Department of Kinesiology and Health Sciences University of Waterloo Waterloo Ontario 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