Cardiovascular response at maximal exercise at high altitude.

Abstract

Letter to the EditorCardiovascular response at maximal exercise at high altitudeJean-Paul Richalet and Eric HermandJean-Paul RichaletUMR INSERM U1272 Hypoxie & Poumon, Université Sorbonne Paris Nord, Paris, France and Eric HermandULR 7369 - URePSSS - Unité de Recherche Pluridisciplinaire Sport Santé Société, Université Littoral Côte d’Opale, Université Artois, Université Lille, CHU Lille, Dunkerque, FrancePublished Online:02 Jan 2023https://doi.org/10.1152/japplphysiol.00609.2022MoreSectionsPDF (166 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat to the editor: We read with great interest the article by Alex Lloyd et al. (1) proposing various models for predicting cardiovascular responses at rest and during exercise in extreme conditions. Among them, altitude drew our attention, as the prediction model seems to be based on erroneous assumptions. The authors assume that maximal cardiac output is not modified with increasing altitude, which is the opposite of common knowledge. From the two quoted papers, by PD Wagner (2), to support this assumption, none of them assumes a constancy of maximal cardiac output. Conversely, the first sentence of the abstract of one paper mentions: “When a lowlander ascends to altitude and acclimatizes over days to weeks, both maximal exercise capacity and maximal cardiac output are reduced compared to sea level.” Moreover, the title itself of the article says: “Reduced maximal cardiac output at altitude…” (2). This observation is confirmed by numerous other studies showing that cardiac output or heart rate at maximal exercise decrease with altitude. As stroke volume decreases, or at the most, does not change with altitude, a decrease in maximal heart rate means a decrease in maximal cardiac output. Therefore, the whole model concerning the effect of altitude is not compatible with major knowledge in its current state since it is based on a major erroneous hypothesis. A model of myocardial oxygenation at exercise at high altitude was recently proposed, developed from all publications focusing on maximal exercise at high altitude and its consequences on cardiac function. This paper is based on 22 studies showing a decrease in maximal heart rate with increasing altitude from 3,090 to 8,840 m (3). Therefore, we strongly suggest a major correction update for this model, nevertheless very interesting for its attempt to consider the effects of several environmental stresses on cardiovascular responses.DISCLOSURESNo conflicts of interest, financial or otherwise, are declared by the authors.AUTHOR CONTRIBUTIONSJ.-P.R. and E.H. conceived and designed research; J.-P.R. and E.H. interpreted results of experiments; J.-P.R. prepared figures; J.-P.R. drafted manuscript; J.-P.R. and E.H. edited and revised manuscript; J.-P.R. and E.H. approved final version of manuscript.REFERENCES1. Lloyd A, Fiala D, Heyde C, Havenith G. A mathematical model for predicting cardiovascular responses at rest and during exercise in demanding environmental conditions. J Appl Physiol (1985) 133: 247–261, 2022. doi:10.1152/japplphysiol.00619.2021.Link | ISI | Google Scholar2. Wagner PD. Reduced maximal cardiac output at altitude–mechanisms and significance. Respir Physiol 120: 1–11, 2000. doi:10.1016/s0034-5687(99)00101-2.Crossref | PubMed | Google Scholar3. Richalet J, Hermand E. Modeling the oxygen transport to the myocardium at maximal exercise at high altitude. Physiological Reports 10: e15262, 2022. doi:10.14814/phy2.15262. Crossref | PubMed | ISI | Google ScholarAUTHOR NOTESCorrespondence: J.-P. Richalet ([email protected]fr). Download PDF Previous Back to Top Next FiguresReferencesRelatedInformation Collections Related ArticlesA mathematical model for predicting cardiovascular responses at rest and during exercise in demanding environmental conditions 28 Jul 2022Journal of Applied PhysiologyReply to Richalet and Hermand. Updating the CVR model for limitations in maximum myocardial contractility at high altitude 02 Jan 2023Journal of Applied PhysiologyCited ByReply to Richalet and Hermand. Updating the CVR model for limitations in maximum myocardial contractility at high altitudeAlex B. Lloyd and George Havenith2 January 2023 | Journal of Applied Physiology, Vol. 134, No. 1 More from this issue > Volume 134Issue 1January 2023Pages 147-147 Crossmark Copyright & PermissionsCopyright © 2023 the American Physiological Society.https://doi.org/10.1152/japplphysiol.00609.2022PubMed36592408History Received 17 October 2022 Accepted 9 November 2022 Published online 2 January 2023 Published in print 1 January 2023 Keywordsaltitudeheart ratehypoxiamathematical model Metrics