Man as a breath-hold diver

There are many thousands of both recreational and professional divers daily engaged in breath-hold diving throughout the world. The most widely known breath-hold divers are found among males and females in Japan and Korea, collectively called the ama. However, compared with many diving animals, man's ability as a breath-hold diver is very much limited. The average duration of a dive is 30–60 s, although one can dive for a period of up to 2–3 min. Usual depths of dive are 5–20 m. However, Jacques Mayol dove to 105 m in 1983, setting a new world record. It is still not clearly understood how one can reach such a depth without developing a pulmonary "squeeze." Human divers also display a mild but significant diving bradycardia which is often accompanied by cardiac arrhythmias. Although the cardiac output decreases slightly, the arterial blood pressure increases during breath holding. It has been suggested, but not unequivocally demonstrated that these cardiovascular changes observed during diving in man subserve to conserve O2 as in diving animals. Human divers descend to the bottom while retaining a considerable amount of air in the lung, thus allowing diffusion of N2 into the blood. As a result, human breath-hold divers can develop decompression sickness if they dive to deeper depths frequently enough. The major limiting factor for human divers is the loss of body heat to the surrounding medium (water) which has a high thermoconductivity. The subcutaneous fat thickness of human divers is much less than that in diving animals and thus human divers are at a great disadvantage. Although repetitive exposures to cold water stress are known to induce a significant cold acclimatization in man, these changes are rather ineffective in prolonging cold water diving time.

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Tolerance to extreme cold at altitude in a Nepalese pilgrim

Journal of Applied Physiology ◽

10.1152/jappl.1963.18.6.1234 ◽

1963 ◽

Vol 18 (6) ◽

pp. 1234-1238 ◽

Cited By ~ 21

Author(s):

L. G. C. E. Pugh

Keyword(s):

Body Temperature ◽

Skin Temperature ◽

Rectal Temperature ◽

Cold Water ◽

Subcutaneous Fat ◽

Subcutaneous Fat Thickness ◽

Fat Thickness ◽

Extreme Cold

Body temperature and respiratory experiments are reported on a Nepalese pilgrim who survived, uninjured, 4 days of exposure at 15,000–17,500 ft in midwinter, wearing only light clothing and no shoes or gloves. His resistance to cold depended on elevation of metabolism and, unlike tolerance of immersion in cold water, was not related to subcutaneous fat thickness. He slept soundly in spite of the cold and so did not become exhausted. In 3–4-hr experiments at o C (clothed), rectal temperature and skin temperature over the trunk showed only minor changes; hand and foot temperatures did not fall below 10–13 C. Maintenance of body temperature was accounted for by elevation of metabolism. survival in cold Submitted on February 19, 1963

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Temperature effect on the human dive response in relation to cold water near-drowning

Journal of Applied Physiology ◽

10.1152/jappl.1984.56.1.202 ◽

1984 ◽

Vol 56 (1) ◽

pp. 202-206 ◽

Cited By ~ 46

Author(s):

J. S. Hayward ◽

C. Hay ◽

B. R. Matthews ◽

C. H. Overweel ◽

D. D. Radford

Keyword(s):

Heart Rate ◽

Water Temperature ◽

Cold Water ◽

Breath Holding ◽

Breath Hold ◽

Cold Stimulation ◽

Near Drowning ◽

Voluntary Hyperventilation ◽

Dive Response ◽

Breath Hold Duration

To facilitate analysis of mechanisms involved in cold water near-drowning, maximum breath-hold duration (BHD) and diving bradycardia were measured in 160 humans who were submerged in water temperatures from 0 to 35 degrees C at 5 degrees C intervals. For sudden submersion BHD was dependent on water temperature (Tw) according to the equation BHD = 15.01 + 0.92Tw. In cold water (0–15 degrees C), BHD was greatly reduced, being 25–50% of the presubmersion duration. BHD after brief habituation to water temperature and mild, voluntary hyperventilation was more than double that of sudden submersion and was also dependent on water temperature according to the equation BHD = 38.90 + 1.70Tw. Minimum heart rate during both types of submersions (diving bradycardia) was independent of water temperature. The results are pertinent to accidental submersion in cold water and show that decreased breath-holding capacity caused by peripheral cold stimulation reduces the effectiveness of the dive response and facilitates drowning. These findings do not support the postulate that the dive response has an important role in the enhanced resuscitatibility associated with cold water near-drowning, thereby shifting emphasis to hypothermia as the mechanism for this phenomenon.

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Spleen volume and blood flow response to repeated breath-hold apneas

Journal of Applied Physiology ◽

10.1152/japplphysiol.00221.2003 ◽

2003 ◽

Vol 95 (4) ◽

pp. 1460-1466 ◽

Cited By ~ 83

Author(s):

Darija Baković ◽

Zoran Valic ◽

Davor Eterović ◽

Ivica Vuković ◽

Ante Obad ◽

...

Keyword(s):

Blood Flow ◽

Cold Water ◽

Splenic Vein ◽

Arterial Blood Flow ◽

Breath Hold ◽

Spleen Volume ◽

Blood Flows ◽

Arterial Blood ◽

Active Contraction ◽

Spleen Contraction

The purpose of this study was 1) to answer whether the reduction in spleen size in breath-hold apnea is an active contraction or a passive collapse secondary to reduced splenic arterial blood flow and 2) to monitor the spleen response to repeated breath-hold apneas. Ten trained apnea divers and 10 intact and 7 splenectomized untrained persons repeated five maximal apneas (A1-A5) with face immersion in cold water, with 2 min interposed between successive attempts. Ultrasonic monitoring of the spleen and noninvasive cardiopulmonary measurements were performed before, between apneas, and at times 0, 10, 20, 40, and 60 min after the last apnea. Blood flows in splenic artery and splenic vein were not significantly affected by breath-hold apnea. The duration of apneas peaked after A3 (143, 127, and 74 s in apnea divers, intact, and splenectomized persons, respectively). A rapid decrease in spleen volume (∼20% in both apnea divers and intact persons) was mainly completed throughout the first apnea. The spleen did not recover in size between apneas and only partly recovered 60 min after A5. The well-known physiological responses to apnea diving, i.e., bradycardia and increased blood pressure, were observed in A1 and remained unchanged throughout the following apneas. These results show rapid, probably active contraction of the spleen in response to breath-hold apnea in humans. Rapid spleen contraction and its slow recovery may contribute to prolongation of successive, briefly repeated apnea attempts.

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Time course of deacclimatization to cold water immersion in Korean women divers

Journal of Applied Physiology ◽

10.1152/jappl.1983.54.6.1708 ◽

1983 ◽

Vol 54 (6) ◽

pp. 1708-1716 ◽

Cited By ~ 24

Author(s):

Y. S. Park ◽

D. W. Rennie ◽

I. S. Lee ◽

Y. D. Park ◽

K. S. Paik ◽

...

Keyword(s):

Longitudinal Study ◽

Time Course ◽

Cold Water ◽

Water Immersion ◽

Subcutaneous Fat ◽

Seasonal Fluctuation ◽

Cold Water Immersion ◽

Korean Women ◽

Subcutaneous Fat Thickness ◽

Fat Thickness

Seasonal basal metabolic rates (BMR), critical water temperature (Tcw), maximal body insulations (Imax), and finger blood flow during hand immersion in 6 degrees C water (Q finger) were measured periodically during the course of a 3-yr longitudinal study (1980–1982) of modern Korean diving women (ama), who have been wearing wet suits since 1977 to avoid cold stress during work. Methods and protocols were identical to previous studies of cotton-suited ama from 1961–1974. The BMR of modern ama did not undergo seasonal fluctuation (1980–1981) and was within the DuBois standard and comparable to nondivers year around Tcw of ama was still reduced by 2–3 degrees C in 1980 but increased progressively to equal that of nondivers in 1982, when compared at comparable subcutaneous fat thickness (SFT). Since modern ama and nondivers have 2.4 times thicker SFT (i.e., 4–13 mm) than in 1962 the absolute Tcw is significantly reduced. Q finger of ama was also significantly lower than controls in 1980 but in 1981–1982 was identical to controls. Imax of modern ama was identical to controls of comparable SFT in 1980–1982. The time course of cold deacclimatization thus was BMR, 3 yr; Imax, 3 yr; Q finger, 4 yr; and Tcw, 5 yr. This longitudinal study provides further evidence that acclimatization to cold did at one time exist in these diving women.

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Thermal insulation and shivering threshold in Greek sponge divers

Journal of Applied Physiology ◽

10.1152/jappl.1982.52.4.845 ◽

1982 ◽

Vol 52 (4) ◽

pp. 845-850 ◽

Cited By ~ 2

Author(s):

A. Veicsteinas ◽

D. W. Rennie

Keyword(s):

Sharp Increase ◽

Cold Water ◽

Subcutaneous Fat ◽

Long Time ◽

Subcutaneous Fat Thickness ◽

Fat Thickness ◽

Tissue Insulation ◽

Relationship Of ◽

The Relationship ◽

Average Skin

Sublingual temperature (Tor), average skin temperature (Tsk), and skin heat flow (Hsk) were determined in a field study for six Greek sponge divers and seven nondiving controls during head-out immersions at water temperature of 21 degrees C. Wetsuits kept Tsk at 22–28 degrees C for 1–3 h until Tor fell to 36.5–35.5 degrees C and violent shivering [metabolic rate (M) = 100–150 W . m-2] ended the test. At a steady Tsk, immediately before shivering, overall tissue insulation (It), calculated as (Tor--Tsk)/Hsk, was linearly related to mean subcutaneous fat thickness (MFT) in both groups without statistical difference between them. The onset of shivering, as detected by a sharp increase of M, occurred at the same Tor for a Tsk of about 26 degrees C, and the relationship of M vs. Tor (i.e., metabolic sensitivity) was the same for both groups. Contrary to other groups accustomed to diving in cold water, the use of a wetsuit for a long time has evidently prevented cold adaptation in these divers.

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Role of cerebral blood flow in extreme breath holding

Translational Neuroscience ◽

10.1515/tnsci-2016-0003 ◽

2016 ◽

Vol 7 (1) ◽

Cited By ~ 4

Author(s):

Anthony R. Bain ◽

Philip N. Ainslie ◽

Ryan L. Hoiland ◽

Chris K. Willie ◽

David B. MacLeod ◽

...

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Oral Administration ◽

Blood Gases ◽

Breath Holding ◽

Breath Hold ◽

Cyclooxygenase Inhibitor ◽

Arterial Blood Gases ◽

Arterial Blood

AbstractThe role of cerebral blood flow (CBF) on a maximal breath-hold (BH) in ultra-elite divers was examined. Divers (n = 7) performed one control BH, and one BH following oral administration of the non-selective cyclooxygenase inhibitor indomethacin (1.2 mg/kg). Arterial blood gases and CBF were measured prior to (baseline), and at BH termination. Compared to control, indomethacin reduced baseline CBF and cerebral delivery of oxygen (CDO

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Effects of Breath-Holding Tests on PetCO2 and Arterial Blood Oxygenation in Men

Ukraïnsʹkij žurnal medicini bìologìï ta sportu ◽

10.26693/jmbs06.05.423 ◽

2021 ◽

Vol 6 (5) ◽

pp. 423-429

Author(s):

A. A. Pytel ◽

◽

S. O. Kovalenko

Keyword(s):

Recovery Period ◽

Statistical Processing ◽

Blood Oxygenation ◽

Breath Holding ◽

Breath Hold ◽

External Respiration ◽

Group Iii ◽

Arterial Blood ◽

Individual Features ◽

Level I

To evaluate the state of external respiration system, breath-holding tests are usually used. However, there are few studies of the peculiarities of the gas exchange in breath-holding with previous hyperventilation. The purpose of the study was to analyze the dynamics of changes in the PetCO2 level and arterial blood oxygenation during breath-holding tests with and without previous hyperventilation in healthy young men. Materials and methods. The СО2 level was recorded in the side stream on the Datex Normocap capnograph (Datex, Finland). This value was recorded for 5 minutes at rest, 5 minutes after half-breath hold, for 5 minutes of regulated breathing with a frequency of 30 cycles per minute, 5 minutes after half-breath hold. The capnogram, atmospheric pressure level and humidity were used to assess the level of СО2 at the end of exhalation (PetCO2), respiratory rate, the ratio of inspiratory duration to expiratory duration (Rie). Statistical processing of the results was performed by parametric methods. According to the method of sigmoid deviation, three groups of individuals were distinguished by the PetCO2 level: I – PetCO2 < 32.7 mmHg, II – PetCO2 – 32.7-36.2 mmHg, III – PetCO2 > 36.2 mmHg. Results and discussion. Breath-holding during the test after hyperventilation was significantly greater than in the first attempt (62.99±3.31 s and 33.78±2.24 s, p <0.001). Visual qualitative and quantitative analysis of capnograms and graphs of arterial blood oxygenation revealed significant inter-individual features of the reactions of these indicators to tests. Therefore, changes in PetCO2 were compared depending on its initial level. After the breath-holding test, the PetCO2 levels on average during the 5-minute recovery reliably decreased in groups II and III compared with I. During the test with hyperventilation, a natural significant increase in its level of reactivity was registered, most pronounced in group III (-13.48 mmHg, p <0.001). After the second breath-holding, there was a decrease in PetCO2 compared to the level after the first breath-holding in all groups. However, the level of HbO2 in the tests differed only in group II. Thus, after a breath-holding test, individuals with relatively low PetCO2 did not have its decrease in contrast to those with relatively medium and high levels. The use of hyperventilation potentiates these reactions before breath-holding, and aligns their level after a long recovery period in different groups. Conclusion. The study shows that breath-holding tests without and after hyperventilation significantly affect the level of CO2 stress and arterial blood oxygenation; the breath-holding test after hyperventilation potentiates the decrease in PetCO2 and HbO2 in arterial blood by increasing breath-holding time. There are significant individual features in the reactivity of such physiological parameters

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Large Lung Volumes Delay the Onset of the Physiological Breaking Point During Simulated Diving

Frontiers in Physiology ◽

10.3389/fphys.2021.731633 ◽

2021 ◽

Vol 12 ◽

Author(s):

Paul F. McCulloch ◽

B. W. Gebhart ◽

J. A. Schroer

Keyword(s):

Lung Volume ◽

Blood Gases ◽

Breaking Point ◽

Breath Holding ◽

Breath Hold ◽

Lung Volumes ◽

Arterial Blood ◽

Face Immersion ◽

Residual Capacity ◽

End Tidal

During breath holding after face immersion there develops an urge to breathe. The point that would initiate the termination of the breath hold, the “physiological breaking point,” is thought to be primarily due to changes in blood gases. However, we theorized that other factors, such as lung volume, also contributes significantly to terminating breath holds during face immersion. Accordingly, nine naïve subjects (controls) and seven underwater hockey players (divers) voluntarily initiated face immersions in room temperature water at Total Lung Capacity (TLC) and Functional Residual Capacity (FRC) after pre-breathing air, 100% O2, 15% O2 / 85% N2, or 5% CO2 / 95% O2. Heart rate (HR), arterial blood pressure (BP), end-tidal CO2 (etCO2), and breath hold durations (BHD) were monitored during all face immersions. The decrease in HR and increase in BP were not significantly different at the two lung volumes, although the increase in BP was usually greater at FRC. BHD was significantly longer at TLC (54 ± 2 s) than at FRC (30 ± 2 s). Also, with each pre-breathed gas BHD was always longer at TLC. We found no consistent etCO2 at which the breath holding terminated. BDHs were significantly longer in divers than in controls. We suggest that during breath holding with face immersion high lung volume acts directly within the brainstem to actively delay the attainment of the physiological breaking point, rather than acting indirectly as a sink to produce a slower build-up of PCO2.

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