Priming the cardiodynamic phase of pulmonary oxygen uptake through voluntary modulations of the respiratory pump at the onset of exercise

New Findings What is the central question of this study? The initial increase in oxygen uptake (V̇O2) at exercise onset results from pulmonary perfusion changes secondary to an increased venous return. Breathing mechanics contribute to venous return through abdominal and intrathoracic pressures vari...

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Bibliographic Details
Published in:Experimental physiology 2021-02, Vol.106 (2), p.555-566
Main Authors: Stucky, Frédéric, Aliverti, Andrea, Kayser, Bengt, Uva, Barbara
Format: Article
Language:English
Subjects:
Adult
Alveoli
cardiodynamic phase
Catheters
Esophagus
exercise
Exercise - physiology
Female
Humans
Lung - physiology
Male
Oxygen consumption
Oxygen Consumption - physiology
oxygen uptake kinetics
Pulmonary Gas Exchange
Respiration
respiratory pump
Respiratory Rate - physiology
venous return
Young Adult
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Summary:New Findings What is the central question of this study? The initial increase in oxygen uptake (V̇O2) at exercise onset results from pulmonary perfusion changes secondary to an increased venous return. Breathing mechanics contribute to venous return through abdominal and intrathoracic pressures variation. Can voluntary breathing techniques (abdominal or rib cage breathing) increase venous return and improve V̇O2 at exercise onset? What is the main finding and its importance? Abdominal and rib cage breathing increase venous return and V̇O2 at exercise onset. This mechanism could be clinically relevant in patients with impaired cardiac function limiting oxygen transport. We examined how different breathing patterns can modulate venous return and alveolar gas transfer during exercise transients in humans. Ten healthy men transitioned from rest to moderate cycling while breathing spontaneously (SP) or with voluntary increases in abdominal (AB) or intrathoracic (RC) pressure swings. We used double body plethysmography to determine blood displacements between the trunk and the extremities (Vbs). From continuous signals of airflow and O2 fraction, we calculated breath‐by‐breath oxygen uptake at the mouth and used optoelectronic plethysmography to correct for lung O2 store changes and calculate alveolar O2 transfer (V̇O2A). Oesophageal (Poes) and gastric (Pga) pressures were monitored using balloon‐tipped catheters. Cardiac stroke volume was measured using impedance cardiography. During the cardiodynamic phase (Φ1) of V̇O2A‐on kinetics (20 s following exercise onset), AB and RC increased total alveolar oxygen transfer compared to SP (227 ± 32, P = 0.019 vs. 235 ± 27, P = 0.001 vs. 206 ± 20 ml, mean ± SD). Pga and Poes swings increased with AB (by 24.4 ± 9.6 cmH2O, P 
ISSN:0958-0670
1469-445X
DOI:10.1113/EP089180