title: The oxygen-conserving potential of the diving response: A kinetic-based analysis.
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.
authors.affiliation: a CETAPS Laboratory , Normandie University , Mont Saint-Aignan , France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Costalat
authors.affiliation: a CETAPS Laboratory , Normandie University , Mont Saint-Aignan , France.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Coquart
authors.affiliation: a CETAPS Laboratory , Normandie University , Mont Saint-Aignan , France.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Castres
authors.affiliation: b UMR MD2, Aix Marseille University and IRBA , Marseille , France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Joulia
authors.affiliation: a CETAPS Laboratory , Normandie University , Mont Saint-Aignan , France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Sirost
authors.affiliation: c NRS-EPHE , USR3278 , Papetoai , French Polynesia.
authors.forename: Eric
authors.initials: E
authors.lastname: Clua
authors.affiliation: a CETAPS Laboratory , Normandie University , Mont Saint-Aignan , France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lemaître
mesh_terms: D000328:Adult; D062485:Breath Holding; D002302:Cardiac Output; D004242:Diving / Q000502:physiology*; D006321:Heart / Q000502:physiology; D006339:Heart Rate; D006439:Hemodynamics; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000378:metabolism; D011659:Pulmonary Gas Exchange; D019265:Spectroscopy, Near-Infrared; D013318:Stroke Volume
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin; D010100:Oxygen
keywords: Diving reflex; NIRS; breath-holding; haemodynamics; kinetics; oxygen-conserving effect