Cardiovascular Responses during Free-Diving in the Sea

Marongiu, Elisabetta; Crisafulli, Antonio; Ghiani, Giovanna; Olla, Sergio; Roberto, Silvana; Pinna, Marco; Pusceddu, Matteo M.; Palazzolo, Girolamo; Sanna, Ignazio; Concu, Alberto; Tocco, Filippo

doi:10.1055/s-0034-1389969

Cited by 16 publications

(19 citation statements)

References 28 publications

(31 reference statements)

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“…However, considering the competitive situation, swimming distance, and repeated dynamic apneas, these increases seem mild, although in agreement with recent studies (Marongiu et al. ; Rodríguez‐Zamora et al. ).…”

Section: Discussionsupporting

confidence: 91%

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Physiological stress markers during breath‐hold diving and SCUBA diving

et al. 2019

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This study investigated the sources of physiological stress in diving by comparing SCUBA dives (stressors: hydrostatic pressure, cold, and hyperoxia), apneic dives (hydrostatic pressure, cold, physical activity, hypoxia), and dry static apnea (hypoxia only). We hypothesized that despite the hypoxia induces by a long static apnea, it would be less stressful than SCUBA dive or apneic dives since the latter combined high pressure, physical activity, and cold exposure. Blood samples were collected from 12 SCUBA and 12 apnea divers before and after dives. On a different occasion, samples were collected from the apneic group before and after a maximal static dry apnea. We measured changes in levels of the stress hormones cortisol and copeptin in each situation. To identify localized effects of the stress, we measured levels of the cardiac injury markers troponin ( cTnI ) and brain natriuretic peptide ( BNP ), the muscular stress markers myoglobin and lactate), and the hypoxemia marker ischemia‐modified albumin ( IMA ). Copeptin, cortisol, and IMA levels increased for the apneic dive and the static dry apnea, whereas they decreased for the SCUBA dive. Troponin, BNP , and myoglobin levels increased for the apneic dive, but were unchanged for the SCUBA dive and the static dry apnea. We conclude that hypoxia induced by apnea is the dominant trigger for the release of stress hormones and cardiac injury markers, whereas cold or and hyperbaric exposures play a minor role. These results indicate that subjects should be screened carefully for pre‐existing cardiac diseases before undertaking significant apneic maneuvers.

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Section: Discussionsupporting

confidence: 91%

“…Indeed, electrocardiographic abnormalities (Marongiu et al. ; Zelenkova and Chomahidze ) or a decrease in stroke volume (Gargne et al. ) were previously described during apneic dive and attributed to the effect of pressure and/or hypoxemia.…”

Section: Discussionmentioning

confidence: 96%

Physiological stress markers during breath‐hold diving and SCUBA diving

et al. 2019

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“…As classically described, the functional role for peripheral vasoconstriction during a breath hold is to prioritize oxygen‐rich blood flow to the brain and to attenuate the decline in oxygen saturation by increasing circulating haemoglobin concentration through splenic contractions (Espersen, Frandsen, Lorentzen, Kanstrup, & Christensen, ) and by forcing the hypoxic skeletal muscle tissue towards non‐oxidative metabolism (Ferretti, ). This latter non‐oxidative metabolic response might play a leading role in oxygen conservation during dynamic/diving breath holds (Andersson & Evaggelidis, ; Andersson, Liner, Fredsted, & Schagatay, ; Marongiu et al., ). However, evidence for a shift towards non‐oxidative skeletal muscle metabolism during a dry static breath hold in elite apneists is less evident.…”

Section: Cardiovascular Regulation and The Dive Responsementioning

confidence: 99%

“…For example, in considering increases in plasma lactate as a rough proxy for increases in non‐oxidative metabolism (from the anaerobic conversion of pyruvate to lactate), an increase in anaerobic metabolism is likely to be minimal given that circulating lactate increases only modestly by ∼0.3 mmol l −1 (absolute at ∼1.3 mmol l −1 ) during dry static breath holds lasting ∼5 min (Bain et al., , ). In comparison, plasma lactate may increase to ∼4 mmol l −1 during depth dives to 30 m (Marongiu et al., ) and >10 mmol l −1 during strenuous exercise (van Loon, Greenhaff, Constantin‐Teodosiu, Saris, & Wagenmakers, ).…”

Section: Cardiovascular Regulation and The Dive Responsementioning

confidence: 99%

“…The magnitude of the increase in MAP during a breath hold is variable, but appears similar whether it is performed in dry (out of water) or wet (water immersion) conditions (Breskovic et al, 2011b). [The increase in blood pressure is, of course, accentuated when the breath hold is performed with exercise (Breskovic et al, 2011b;Marongiu et al, 2015).] On average, in elite apneists MAP is increased at the termination of a static dry breath hold (>5 min) by 35-55% (absolute up to ∼160 mmHg) from supine resting values (Bain et al, 2015a;Breskovic et al, 2011b;Willie et al, 2015), resulting from elevations in both systolic and diastolic pressure (Breskovic et al, 2011b;Perini et al, 2008).…”

Section: Blood Pressure and Baroreceptionmentioning

confidence: 99%

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Physiology of static breath holding in elite apneists

Bain

Drviš

Dujić

et al. 2018

Experimental Physiology

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Breath-hold-related activities have been performed for centuries, but only recently, within the last ∼30 years, has it emerged as an increasingly popular competitive sport. In apnoea sport, competition relates to underwater distances or simply maximal breath-hold duration, with the current (oxygen-unsupplemented) static breath-hold record at 11 min 35 s. Remarkably, many ultra-elite apneists are able to suppress respiratory urges to the point where consciousness fundamentally limits a breath-hold duration. Here, arterial oxygen saturations as low as ∼50% have been reported. In such cases, oxygen conservation to maintain cerebral functioning is critical, where responses ascribed to the mammalian dive reflex, e.g. sympathetically mediated peripheral vasoconstriction and vagally mediated bradycardia, are central. In defence of maintaining global cerebral oxygen delivery during prolonged breath holds, the cerebral blood flow may increase by ∼100% from resting values. Interestingly, near the termination of prolonged dry static breath holds, recent studies also indicate that reductions in the cerebral oxidative metabolism can occur, probably attributable to the extreme hypercapnia and irrespective of the hypoxaemia. In this review, we highlight and discuss the recent data on the cardiovascular, metabolic and, particularly, cerebrovascular function in competitive apneists performing maximal static breath holds. The physiological adaptation and maladaptation with regular breath-hold training are also summarized, and future research areas in this unique physiological field are highlighted; particularly, the need to determine the potential long-term health impacts of extreme breath holding.

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Unlocking the depths: multiple factors contribute to risk for hypoxic blackout during deep freediving

et al. 2023

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Purpose To examine the effect of freediving depth on risk for hypoxic blackout by recording arterial oxygen saturation (SpO2) and heart rate (HR) during deep and shallow dives in the sea. Methods Fourteen competitive freedivers conducted open-water training dives wearing a water-/pressure proof pulse oximeter continuously recording HR and SpO2. Dives were divided into deep (> 35 m) and shallow (10–25 m) post-hoc and data from one deep and one shallow dive from 10 divers were compared. Results Mean ± SD depth was 53 ± 14 m for deep and 17 ± 4 m for shallow dives. Respective dive durations (120 ± 18 s and 116 ± 43 s) did not differ. Deep dives resulted in lower minimum SpO2 (58 ± 17%) compared with shallow dives (74 ± 17%; P = 0.029). Overall diving HR was 7 bpm higher in deep dives (P = 0.002) although minimum HR was similar in both types of dives (39 bpm). Three divers desaturated early at depth, of which two exhibited severe hypoxia (SpO2 ≤ 65%) upon resurfacing. Additionally, four divers developed severe hypoxia after dives. Conclusions Despite similar dive durations, oxygen desaturation was greater during deep dives, confirming increased risk of hypoxic blackout with increased depth. In addition to the rapid drop in alveolar pressure and oxygen uptake during ascent, several other risk factors associated with deep freediving were identified, including higher swimming effort and oxygen consumption, a compromised diving response, an autonomic conflict possibly causing arrhythmias, and compromised oxygen uptake at depth by lung compression possibly leading to atelectasis or pulmonary edema in some individuals. Individuals with elevated risk could likely be identified using wearable technology.

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Cardiovascular Responses during Free-Diving in the Sea

Cited by 16 publications

References 28 publications

Physiological stress markers during breath‐hold diving and SCUBA diving

Physiological stress markers during breath‐hold diving and SCUBA diving

Physiology of static breath holding in elite apneists

Unlocking the depths: multiple factors contribute to risk for hypoxic blackout during deep freediving

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