The Circulatory Effects of Increased Hydrostatic Pressure Due to Immersion and Submersion

Weenink, Robert P.; Wingelaar, Thijs T.

doi:10.3389/fphys.2021.699493

Cited by 7 publications

(5 citation statements)

References 14 publications

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“…Diving is often preferred because it is an activity during which divers experience relaxation and stress reduction ( 37 ) while deep and controlled breathing leads to calmness, like meditation ( 38 – 40 ). In addition, this effect could be also contributed by a feeling of weightlessness, which is a result of the abolished effect of gravity due to buoyancy ( 41 ). However, it should be also taken into consideration that cortisol and ACTH are known for their distinctive circadian rhythm ( 42 ), i.e., they reach their peak concentrations between 6:00 and 10:00 am and significantly decline afterward.…”

Section: Discussionmentioning

confidence: 99%

Effects of recreational SCUBA diving practiced once a week on neurohormonal response and myokines-mediated communication between muscles and the brain

Bratičević

Žarak

Simac

et al. 2023

Front. Cardiovasc. Med.

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ObjectiveDuring physical activity, activation of muscular, endocrine, and nervous systems, results in intensive crosstalk between muscles and other organs, which enables response to physiological stress. In SCUBA diving, extreme environmental conditions represent an additional challenge for homeostasis maintenance, but underlying mechanisms are largely unknown. We aimed to contribute to the understanding of neurohormonal response and muscle-brain crosstalk by measuring the concentrations of the selected hormones secreted by the pituitary-target organ axis and myokines involved in the muscle-brain endocrine loop in recreational SCUBA (rSCUBA) divers.MethodsFourteen male divers performed five open-water recreational dives (one per week, depth of 20–30 m, lasting 30 min, between 9 and 10 am), after a winter non-diving period of 5 months. Blood samples were collected immediately before and after the first, third, and fifth dives. Adrenocorticotropic hormone (ACTH), cortisol, thyroid-stimulating hormone (TSH), free thyroxine (fT4), prolactin, total testosterone, growth hormone (GH), insulin-like growth factor-1 (IGF-1), irisin, brain-derived neurotrophic factor (BDNF), S100B, glial fibrillary acidic protein (GFAP), and neuron-specific enolase (NSE) were measured using commercially available immunoassays.ResultsCortisol and ACTH levels decreased after every dive, while total testosterone decreased only after the first dive. No significant changes in post-dive values, as well as the cumulative effect on any other measured hormone, were observed. Although irisin and BDNF levels decreased after the first and third dives, the fifth dive caused a significant increase in both myokines. Changes in IGF-1 levels were not observed. All three dives caused a significant increase in S100B levels. A statistically significant decrease in GFAP concentration was observed after every dive, while NSE pre-dive concentration declined over the studied period. The cumulative effect on myokine levels was reflected in a continuous decline in irisin and BDNF pre-dive levels throughout the studied period, but an increasing trend after the fifth dive was observed.ConclusionsObserved changes in myokines and hormone levels point to a specific response to rSCUBA practiced once a week, most likely due to extreme environmental conditions. Further studies on communication between muscles and other organ systems, particularly on the muscle-brain endocrine loop, are required for a deeper understanding of the adaptation mechanisms to this kind of physiological stress.

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Section: Discussionmentioning

confidence: 99%

Effects of recreational SCUBA diving practiced once a week on neurohormonal response and myokines-mediated communication between muscles and the brain

Bratičević

Žarak

Simac

et al. 2023

Front. Cardiovasc. Med.

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“…We noted with interest the article by Weenink and Wingelaar published last July in Frontiers in Physiology (Weenink and Wingelaar, 2021). However, reading the abstract and the article was largely disappointing.…”

Section: A Commentary Onmentioning

confidence: 98%

Commentary: The Circulatory Effects of Increased Hydrostatic Pressure Due to Immersion and Submersion

Regnard¹,

Bouhaddi²,

Castagna³

et al. 2022

Front. Physiol.

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“…Measurements were all done during dry apneas after glossopharyngeal insufflation, which limits venous return ( Eichinger et al, 2010 ). As submersion during diving may cause 500-700 mL increase in circulating volume ( Weston et al, 1987 ; Weenink and Wingelaar, 2021 ) future studies may reveal the most important reservoirs of blood and volume changes during human apnea diving.…”

Section: Limitationsmentioning

confidence: 99%

Hemoglobin concentration and blood shift during dry static apnea in elite breath hold divers

Kjeld,

Krag,

Brenøe

et al. 2024

Front. Physiol.

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IntroductionElite breath-hold divers (BHD) enduring apneas of more than 5 min are characterized by tolerance to arterial blood oxygen levels of 4.3 kPa and low oxygen-consumption in their hearts and skeletal muscles, similar to adult seals. Adult seals possess an adaptive higher hemoglobin-concentration and Bohr effect than pups, and when sedated, adult seals demonstrate a blood shift from the spleen towards the brain, lungs, and heart during apnea. We hypothesized these observations to be similar in human BHD. Therefore, we measured hemoglobin- and 2,3-biphosphoglycerate-concentrations in BHD (n = 11) and matched controls (n = 11) at rest, while myocardial mass, spleen and lower extremity volumes were assessed at rest and during apnea in BHD.Methods and resultsAfter 4 min of apnea, left ventricular myocardial mass (LVMM) determined by 15O-H2O-PET/CT (n = 6) and cardiac MRI (n = 6), was unaltered compared to rest. During maximum apnea (∼6 min), lower extremity volume assessed by DXA-scan revealed a ∼268 mL decrease, and spleen volume, assessed by ultrasonography, decreased ∼102 mL. Compared to age, BMI and VO2max matched controls (n = 11), BHD had similar spleen sizes and 2,3- biphosphoglycerate-concentrations, but higher total hemoglobin-concentrations.ConclusionOur results indicate: 1) Apnea training in BHD may increase hemoglobin concentration as an oxygen conserving adaptation similar to adult diving mammals. 2) The blood shift during dry apnea in BHD is 162% more from the lower extremities than from the spleen. 3) In contrast to the previous theory of the blood shift demonstrated in sedated adult seals, blood shift is not towards the heart during dry apnea in humans.

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The Circulatory Effects of Increased Hydrostatic Pressure Due to Immersion and Submersion

Cited by 7 publications

References 14 publications

Effects of recreational SCUBA diving practiced once a week on neurohormonal response and myokines-mediated communication between muscles and the brain

Effects of recreational SCUBA diving practiced once a week on neurohormonal response and myokines-mediated communication between muscles and the brain

Commentary: The Circulatory Effects of Increased Hydrostatic Pressure Due to Immersion and Submersion

Hemoglobin concentration and blood shift during dry static apnea in elite breath hold divers

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