{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,2]],"date-time":"2025-11-02T16:57:39Z","timestamp":1762102659138,"version":"3.41.2"},"reference-count":46,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,6,21]],"date-time":"2021-06-21T00:00:00Z","timestamp":1624233600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Physiol."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>Respiratory muscle unloading through proportional assist ventilation (PAV) may enhance leg oxygen delivery, thereby speeding off-exercise oxygen uptake (<jats:inline-formula><mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" id=\"INEQ1\"><mml:mrow><mml:mover accent=\"true\"><mml:mtext>V<\/mml:mtext><mml:mo>.<\/mml:mo><\/mml:mover><mml:mo>\u2062<\/mml:mo><mml:msub><mml:mtext>O<\/mml:mtext><mml:mn>2<\/mml:mn><\/mml:msub><\/mml:mrow><\/mml:math><\/jats:inline-formula>) kinetics in patients with heart failure with reduced left ventricular ejection fraction (HFrEF).<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Ten male patients (HFrEF = 26 \u00b1 9%, age 50 \u00b1 13 years, and body mass index 25 \u00b1 3 kg m<jats:sup>2<\/jats:sup>) underwent two constant work rate tests at 80% peak of maximal cardiopulmonary exercise test to tolerance under PAV and sham ventilation. Post-exercise kinetics of <jats:inline-formula><mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" id=\"INEQ2\"><mml:mrow><mml:mover accent=\"true\"><mml:mtext>V<\/mml:mtext><mml:mo>.<\/mml:mo><\/mml:mover><mml:mo>\u2062<\/mml:mo><mml:msub><mml:mtext>O<\/mml:mtext><mml:mn>2<\/mml:mn><\/mml:msub><\/mml:mrow><\/mml:math><\/jats:inline-formula>, vastus lateralis deoxyhemoglobin ([deoxy-Hb + Mb]) by near-infrared spectroscopy, and cardiac output (Q<jats:sub><jats:italic>T<\/jats:italic><\/jats:sub>) by impedance cardiography were assessed.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>PAV prolonged exercise tolerance compared with sham (587 \u00b1 390 s vs. 444 \u00b1 296 s, respectively; <jats:italic>p<\/jats:italic> = 0.01). PAV significantly accelerated <jats:inline-formula><mml:math xmlns:mml=\"http:\/\/www.w3.org\/1998\/Math\/MathML\" id=\"INEQ3\"><mml:mrow><mml:mover accent=\"true\"><mml:mtext>V<\/mml:mtext><mml:mo>.<\/mml:mo><\/mml:mover><mml:mo>\u2062<\/mml:mo><mml:msub><mml:mtext>O<\/mml:mtext><mml:mn>2<\/mml:mn><\/mml:msub><\/mml:mrow><\/mml:math><\/jats:inline-formula> recovery (<jats:italic>\u03c4<\/jats:italic> = 56 \u00b1 22 s vs. 77 \u00b1 42 s; <jats:italic>p<\/jats:italic> &amp;lt; 0.05), being associated with a faster decline in \u0394[deoxy-Hb + Mb] and Q<jats:sub><jats:italic>T<\/jats:italic><\/jats:sub> compared with sham (<jats:italic>\u03c4<\/jats:italic> = 31 \u00b1 19 s vs. 42 \u00b1 22 s and 39 \u00b1 22 s vs. 78 \u00b1 46 s, <jats:italic>p<\/jats:italic> &amp;lt; 0.05). Faster off-exercise decrease in Q<jats:sub><jats:italic>T<\/jats:italic><\/jats:sub> with PAV was related to longer exercise duration (<jats:italic>r<\/jats:italic> = \u22120.76; <jats:italic>p<\/jats:italic> &amp;lt; 0.05).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>PAV accelerates the recovery of central hemodynamics and muscle oxygenation in HFrEF. These beneficial effects might prove useful to improve the tolerance to repeated exercise during cardiac rehabilitation.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fphys.2021.685274","type":"journal-article","created":{"date-parts":[[2021,6,21]],"date-time":"2021-06-21T08:40:50Z","timestamp":1624264850000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":7,"title":["Proportional Assist Ventilation Improves Leg Muscle Reoxygenation After Exercise in Heart Failure With Reduced Ejection Fraction"],"prefix":"10.3389","volume":"12","author":[{"given":"Audrey","family":"Borghi-Silva","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cassia da Luz","family":"Goulart","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cl\u00e1udia R.","family":"Carrascosa","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cristino Carneiro","family":"Oliveira","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Danilo C.","family":"Berton","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dirceu Rodrigues","family":"de Almeida","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Luiz Eduardo","family":"Nery","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ross","family":"Arena","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J. 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