The oxygen-conserving potential of the diving response: A kinetic-based analysis |
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| Authors: | Guillaume Costalat Jeremy Coquart Ingrid Castres Fabrice Joulia Olivier Sirost Eric Clua |
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| Institution: | 1. CETAPS Laboratory, Normandie University, Mont Saint-Aignan, France;2. UMR MD2, Aix Marseille University and IRBA, Marseille, France;3. NRS-EPHE, USR3278, Papetoai, French Polynesia |
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| Abstract: | We investigated the oxygen-conserving potential of the human diving response by comparing trained breath-hold divers (BHDs) to non-divers (NDs) during simulated dynamic breath-holding (BH). Changes in haemodynamics heart rate (HR), stroke volume (SV), cardiac output (CO)] and peripheral muscle oxygenation oxyhaemoglobin (HbO2]), deoxyhaemoglobin (HHb]), total haemoglobin (tHb]), tissue saturation index (TSI)] and peripheral oxygen saturation (SpO2) were continuously recorded during simulated dynamic BH. BHDs showed a breaking point in HR kinetics at mid-BH immediately preceding a more pronounced drop in HR (?0.86 bpm.%?1) while HR kinetics in NDs steadily decreased throughout BH (?0.47 bpm.%?1). By contrast, SV remained unchanged during BH in both groups (all P > 0.05). Near-infrared spectroscopy (NIRS) results (mean ± SD) expressed as percentage changes from the initial values showed a lower HHb] increase for BHDs than for NDs at the cessation of BH (+24.0 ± 10.1 vs. +39.2 ± 9.6%, respectively; P < 0.05). As a result, BHDs showed a tHb] drop that NDs did not at the end of BH (?7.3 ± 3.2 vs. ?3.0 ± 4.7%, respectively; P < 0.05). The most striking finding of the present study was that BHDs presented an increase in oxygen-conserving efficiency due to substantial shifts in both cardiac and peripheral haemodynamics during simulated BH. In addition, the kinetic-based approach we used provides further credence to the concept of an “oxygen-conserving breaking point” in the human diving response. |
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| Keywords: | Diving reflex breath-holding haemodynamics kinetics oxygen-conserving effect NIRS |
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