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Kinetics of Left Ventricular Mechanics during Transition from Rest to Exercise

IZEM, OMAR1; MAUFRAIS, CLAIRE1; OBERT, PHILIPPE1; RUPP, THOMAS2; SCHUSTER, IRIS3; NOTTIN, STÉPHANE1

Medicine & Science in Sports & Exercise: September 2019 - Volume 51 - Issue 9 - p 1838–1844
doi: 10.1249/MSS.0000000000002005
BASIC SCIENCES
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Purpose At the onset of physical exercise, oxygen (O2) transport adapts to meet the working muscle O2 demands. Cardiac output abruptly increases through the concomitant changes of HR and stroke volume (SV), which is conditioned by the left ventricular (LV) function. The purpose of this study was to investigate the contribution of many LV diastolic and systolic function parameters, including twist–untwist mechanics, to SV adaptation during the first minutes after exercise onset.

Methods Diastolic and systolic myocardial strains and twist were monitored by two-dimensional speckle-tracking echocardiography with high temporal resolution in 28 young men (mean age, 23 ± 4 yr) who performed five similar constant work-load exercises on a cycloergometer (target HR: 125 bpm). Two-dimensional cine-loops were recorded every 15 s during the first minute of exercise, and then every 30 s for the next 3 min.

Results During the first 60 s of exercise, SV (from 104 ± 15 mL to 126 ± 21 mL, P < 0.001) increased concomitantly with LV strain and strain rates. Early filling was the main SV determinant during this phase, probably linked to the increase of venous return (at the very beginning of exercise), LV relaxation (from 1.5 ± 0.3 s to 2.5 ± 0.4 s, P < 0.001) and untwisting (from −78 ± 34°·s−1 to −165 ± 61°·s−1, P < 0.001). After the first minute, SV remained constant, whereas LV untwisting continued to increase (from −165 ± 61°·s−1 to −187 ± 60°·s−1, P < 0.001) and the other systolic and diastolic parameters reached a plateau.

Conclusions This study gives new mechanical insights into LV kinetics to address the challenge of SV response at the onset of exercise.

1Avignon University, Avignon, FRANCE

2LIBM, Inter-university Laboratory of Human Movement Science, University Savoie Mont Blanc, Chambéry, FRANCE

3Faculty of Medicine, Montpellier University and Nîmes University Hospital Center, Nîmes, FRANCE

Address for correspondence: Stéphane Nottin, Ph.D., EA 4278, Laboratoire de Pharm-Écologie Cardiovasculaire, 33, Rue Louis Pasteur, 84000 Avignon, France; E-mail: stephane.nottin@univ-avignon.fr.

Submitted for publication September 2018.

Accepted for publication March 2019.

Online date: April 19, 2019

© 2019 American College of Sports Medicine