title: Cardiovascular responses during free-diving in the sea.
abstract: Cardiac output has never been assessed during free-diving diving in the sea. Knowledge of human diving response in this setting is therefore scarce. 3 immersions were performed by 7 divers: at depths of 10 m, 20 m and 30 m. Each test consisted of 3 apnea phases: descent, static and ascent. An impedance cardiograph provided data on stroke volume, heart rate and cardiac output. Mean blood pressure, arterial O2 saturation and blood lactate values were also collected. Starting from a resting value of 4.5±1.6 L∙min(-1), cardiac output at 10 m showed an increase up to 7.1±2.2 L∙min(-1) (p<0.01) during the descent, while conditions during the static and ascent phases remained unchanged. At 20 m cardiac output values were 7.3±2.4 L∙min(-1) and 6.7(±1).2 L∙min(-1) during ascent and descent, respectively (p<0.01), and 4.3±0.9 L∙min(-1) during static phase. At 30 m cardiac output values were 6.5±1.8 L∙min(-1) and 7.5±2 L∙min(-1) during descent and ascent, respectively (p<0.01), and 4.7±2.1 L∙min(-1) during static phase. Arterial O2 saturation decreased with increasing dive depth, reaching 91.1±3.4% (p<0.001 vs. rest) upon emergence from a depth of 30 m. Blood lactate values increased to 4.1±1.2 mmol∙L(-1) at the end of the 30 m dive (p<0.001 vs. rest). Results seem to suggest that simultaneous activation of exercise and diving response could lead to an absence of cardiac output reduction aimed at an oxygen-conserving effect.
authors.affiliation: Medical Sciences, University of Cagliari, Cagliari, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Marongiu
authors.affiliation: Science Applied to Biological Systems, University of Cagliari, Cagliari, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Crisafulli
authors.affiliation: Medical Sciences, University of Cagliari, Cagliari, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Ghiani
authors.affiliation: Medical Sciences, University of Cagliari, Cagliari, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Olla
authors.affiliation: University of Cagliari, Clinical Sciences, Cagliari, Cagliari, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Roberto
authors.affiliation: CONI, Italian Regional Olympic Committee, Cagliari, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Pinna
authors.affiliation: Medical Sciences, University of Cagliari, Cagliari, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Pusceddu
authors.affiliation: Medical Sciences, University of Cagliari, Cagliari, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Palazzolo
authors.affiliation: Medical Sciences, University of Cagliari, Cagliari, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Sanna
authors.affiliation: Physiology, University of Cagliari, Cagliari, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Concu
authors.affiliation: Medical Sciences, University of Cagliari, Cagliari, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Tocco
mesh_terms: D000328:Adult; D001794:Blood Pressure; D002302:Cardiac Output; D002307:Cardiography, Impedance; D004242:Diving / Q000502:physiology*; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D010100:Oxygen / Q000097:blood; D013318:Stroke Volume
chemical_list: D019344:Lactic Acid; D010100:Oxygen