Limited matching of the cardiac output response to the peripheral demand of heat stress and exercise

Abstract It is widely accepted that cardiac output matches the prevailing peripheral demand in healthy humans. However, it remains unknown whether stroke volume and heart rate are regulated interdependently to arrive at a specific cardiac output. The aim of this study was to determine whether the he...

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Main Authors: Moritz Lampkemeyer, Jonas Kell, Veit Börß, Tobias Claussen, Fabian Spahiu, Michelle Ottlik, Lars C. Helbig, Craig G. Crandall, Eric J. Stöhr
Format: Article
Language:English
Published: Wiley 2025-05-01
Series:Experimental Physiology
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Online Access:https://doi.org/10.1113/EP092688
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author Moritz Lampkemeyer
Jonas Kell
Veit Börß
Tobias Claussen
Fabian Spahiu
Michelle Ottlik
Lars C. Helbig
Craig G. Crandall
Eric J. Stöhr
author_facet Moritz Lampkemeyer
Jonas Kell
Veit Börß
Tobias Claussen
Fabian Spahiu
Michelle Ottlik
Lars C. Helbig
Craig G. Crandall
Eric J. Stöhr
author_sort Moritz Lampkemeyer
collection DOAJ
description Abstract It is widely accepted that cardiac output matches the prevailing peripheral demand in healthy humans. However, it remains unknown whether stroke volume and heart rate are regulated interdependently to arrive at a specific cardiac output. The aim of this study was to determine whether the healthy human heart responds specifically according to the peripheral demands of heat stress and exercise. Eleven healthy humans (women/men n = 3/8; age = 26 ± 2 years; body mass = 73 ± 11 kg) underwent leg heat stress and cycling exercise (60 W), with and without blood flow restriction (pressure set at the prevailing mean arterial pressure of the individual). Cardiac output was measured with triplane echocardiography. Additionally, haemodynamics, oxygen consumption, carbon dioxide production and lactate were assessed. Data were analysed using two‐way repeated‐measures ANOVA. Despite stable heat and exercise demands, cardiac output decreased significantly with blood flow restriction in both conditions (Δ−0.87 and −1.03 L min−1, 17% and 11%, respectively, p = 0.01), owing to a decline in end‐diastolic volume (p < 0.0001) and stroke volume (p < 0.0001) not sufficiently compensated for by an increase in heart rate (p = 0.001). Importantly, these responses were accompanied by an increased rate of skin temperature rise (p = 0.04) during heat stress and a significantly greater rise in circulating lactate (p < 0.0001) during exercise. The cardiac output response to local heat stress and submaximal exercise does not appear to be entirely specific to the peripheral thermal and energetic requirements. This finding supports the theory that even the healthy heart does not coordinate stroke volume and heart rate to arrive at a specific target output.
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spelling doaj-art-6e3b3de249d04c4cbe9fca0044c918cc2025-08-20T02:11:26ZengWileyExperimental Physiology0958-06701469-445X2025-05-01110572273410.1113/EP092688Limited matching of the cardiac output response to the peripheral demand of heat stress and exerciseMoritz Lampkemeyer0Jonas Kell1Veit Börß2Tobias Claussen3Fabian Spahiu4Michelle Ottlik5Lars C. Helbig6Craig G. Crandall7Eric J. Stöhr8COR‐HELIX, Institute of Sport Science Leibniz University Hannover GermanyCOR‐HELIX, Institute of Sport Science Leibniz University Hannover GermanyCOR‐HELIX, Institute of Sport Science Leibniz University Hannover GermanyCOR‐HELIX, Institute of Sport Science Leibniz University Hannover GermanyCOR‐HELIX, Institute of Sport Science Leibniz University Hannover GermanyCOR‐HELIX, Institute of Sport Science Leibniz University Hannover GermanyCOR‐HELIX, Institute of Sport Science Leibniz University Hannover GermanyDivision of Cardiology, Department of Internal Medicine University of Texas Southwestern Medical Center, Institute for Exercise and Environmental Medicine Dallas Texas USACOR‐HELIX, Institute of Sport Science Leibniz University Hannover GermanyAbstract It is widely accepted that cardiac output matches the prevailing peripheral demand in healthy humans. However, it remains unknown whether stroke volume and heart rate are regulated interdependently to arrive at a specific cardiac output. The aim of this study was to determine whether the healthy human heart responds specifically according to the peripheral demands of heat stress and exercise. Eleven healthy humans (women/men n = 3/8; age = 26 ± 2 years; body mass = 73 ± 11 kg) underwent leg heat stress and cycling exercise (60 W), with and without blood flow restriction (pressure set at the prevailing mean arterial pressure of the individual). Cardiac output was measured with triplane echocardiography. Additionally, haemodynamics, oxygen consumption, carbon dioxide production and lactate were assessed. Data were analysed using two‐way repeated‐measures ANOVA. Despite stable heat and exercise demands, cardiac output decreased significantly with blood flow restriction in both conditions (Δ−0.87 and −1.03 L min−1, 17% and 11%, respectively, p = 0.01), owing to a decline in end‐diastolic volume (p < 0.0001) and stroke volume (p < 0.0001) not sufficiently compensated for by an increase in heart rate (p = 0.001). Importantly, these responses were accompanied by an increased rate of skin temperature rise (p = 0.04) during heat stress and a significantly greater rise in circulating lactate (p < 0.0001) during exercise. The cardiac output response to local heat stress and submaximal exercise does not appear to be entirely specific to the peripheral thermal and energetic requirements. This finding supports the theory that even the healthy heart does not coordinate stroke volume and heart rate to arrive at a specific target output.https://doi.org/10.1113/EP092688blood flowblood flow restrictioncardiovascular controlcardiovascular responseexerciseexercise physiology
spellingShingle Moritz Lampkemeyer
Jonas Kell
Veit Börß
Tobias Claussen
Fabian Spahiu
Michelle Ottlik
Lars C. Helbig
Craig G. Crandall
Eric J. Stöhr
Limited matching of the cardiac output response to the peripheral demand of heat stress and exercise
Experimental Physiology
blood flow
blood flow restriction
cardiovascular control
cardiovascular response
exercise
exercise physiology
title Limited matching of the cardiac output response to the peripheral demand of heat stress and exercise
title_full Limited matching of the cardiac output response to the peripheral demand of heat stress and exercise
title_fullStr Limited matching of the cardiac output response to the peripheral demand of heat stress and exercise
title_full_unstemmed Limited matching of the cardiac output response to the peripheral demand of heat stress and exercise
title_short Limited matching of the cardiac output response to the peripheral demand of heat stress and exercise
title_sort limited matching of the cardiac output response to the peripheral demand of heat stress and exercise
topic blood flow
blood flow restriction
cardiovascular control
cardiovascular response
exercise
exercise physiology
url https://doi.org/10.1113/EP092688
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