Apneothèque

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Spleen contraction during 20 min normobaric hypoxia and 2 min apnea in humans.
Aviat Space Environ Med. 2010 Jun;81(6):545-9
Authors: Lodin-Sundström A, Schagatay E
INTRODUCTION: Spleen contraction occurs in humans during exercise, apnea, and simulated altitude, resulting in ejection of stored red blood cells into circulation. The mechanisms responsible for initiating the contraction are not fully known: hypoxia is likely involved, but other, unknown factors may also contribute. To reveal the initiating factors, we studied its occurrence in two different situations involving similar reductions in arterial oxygen saturation (SaO2). We hypothesized that similar spleen responses would result if the level of hypoxia is the main factor involved. METHODS: Five female and four male healthy volunteers performed two different trials on separate days: (1) 20 min of normobaric hypoxic breathing (14.2% oxygen); and II) 2 min of apnea after a deep inspiration of air. Both trials started and en…

Conclusions: Barotrauma was observed in breath-hold divers who increased their lung volumes by GI. The long-term effects of this barotrauma are uncertain and longitudinal studies are required to assess cumulative lung damage. (Source: Respirology)

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CIH: from sleep apnea to breath-hold diving : Is sympathetic activation inevitable?
Clin Auton Res. 2010 Apr 20;
Authors: Chapleau MW

PMID: 20405161 [PubMed - as supplied by publisher]

We report on a Japanese male professional breath-hold diver (Ama) who developed neurological disorders during repetitive dives to 22 meters of sea water. Each diving duration and surface interval were 40-80 seconds and 20-30 seconds, respectively. He suffe... (Source: SafetyLit: All (Unduplicated))

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Energetics of breath-hold hunting: Modeling the effects of aging on foraging success in the Weddell seal.
J Theor Biol. 2010 Apr 1;
Authors: Hindle AG, Horning M
A simulation model was developed to predict age-related changes in foraging energetics of individual Weddell seals, Leptonychotes weddellii. Aging in diving animals is interesting because their characteristic cyclic sequence of apneustic hunting and eupnea should elevate oxidative stress, possibly accelerating aging. Such a hypothesis can be evaluated by modeling energetics of constrained, time-partitioned activities with well-defined costs. Three possible consequences of physiological aging in divers were specified and appraised. The model examined the potential impacts of age-related decline in muscle contractile ability, increased buoyancy, and reduced aerobic dive limit, alone and in combination, on a daily energy budget. A uniform age effect evident in model outputs is reduced foraging efficiency. The components of this…

Another iPhone table application

For dynamic apnea, having proper bouyancy is key to moving efficiently through the water. While some divers simply wear a weight belt as in depth disciplines, a weight around your neck will better compensate for the extra bouyancy in your lungs, meaning your body will remain level (rather than trying to swim through the water on an angle).

It is possible to buy neck weights, but why bother when it's simple to make your own?

Description from cid-9e3b45e706a6e578.skydrive.live.com:

Designed to run standard and custom tables with audio alerts, the ability to play media files and the ability to run up to 96 consecutive intervals of up to 59:59 each. Compatible with Windows and I think Mac operating systems. Has an extra large timer to assist those of us who are visually challenged.

Description from www.google.com:

iGoogle is your personalized Google page. Add news, photos, weather, and stuff from across the web to your page.

Description from forums.deeperblue.com:

I was getting bored at the computer and am trying to work on my static apnea (my best is 2:25, which i set today during my history exam). so I made these two sound files of the tables. they give you a five second countdown to when it begins, and a five sec til the end.

Summary: The physiological responses to apnea training exhibited by elite breath-hold divers may contribute to improving sports performance. Breath-hold divers have shown reduced blood acidosis, oxidative stress and basal metabolic rate, and increased hematocrit, erythropoietin concentration, hemoglobin mass and lung volumes. We hypothesise that these adaptations contributed to long apnea durations and improve performance. These results suggest that apnea training may be an effective alternative to hypobaric or normobaric hypoxia to increase aerobic and/or anaerobic performance. (Source: Medical Hypotheses)

Condition and mass impact oxygen stores and dive duration in adult female northern elephant seals.
J Exp Biol. 2010 Feb;213(Pt 4):585-92
Authors: Hassrick JL, Crocker DE, Teutschel NM, McDonald BI, Robinson PW, Simmons SE, Costa DP
The range of foraging behaviors available to deep-diving, air-breathing marine vertebrates is constrained by their physiological capacity to breath-hold dive. We measured body oxygen stores (blood volume and muscle myoglobin) and diving behavior in adult female northern elephant seals, Mirounga angustirostris, to investigate age-related effects on diving performance. Blood volume averaged 74.4+/-17.0 liters in female elephant seals or 20.2+/-2.0% of body mass. Plasma volume averaged 32.2+/-7.8 liters or 8.7+/-0.7% of body mass. Absolute plasma volume and blood volume increased independently with mass and age. Hematocrit decreased weakly with mass but did not vary with age. Muscle myoglobin concentration, while higher than previously reported (7.4+/-0.7 g%), did not vary w…

The rat: a laboratory model for studies of the diving response.
J Appl Physiol. 2010 Jan 21;
Authors: Panneton WM, Gan Q, Juric R
Underwater submersion in mammals induces an apnea, a parasympathetically-mediated bradycardia, and a sympathetically-mediated peripheral vasoconstriction. These effects are collectively termed the diving response, potentially the most powerful autonomic reflex known. Although these physiological responses are directed by neurons in the brain, the study of the neural control of the diving response has been hampered since: a) it is difficult to study the brains of animals while they are underwater, b) feral marine mammals are usually large and have brains of variable size, and c) there are but few references on the brains of naturally-diving species. Similar responses are elicited in anesthetized rodents after stimulating their nasal mucosa, but this nasopharyngeal reflex has not been compared directly to natural-diving behavior in the rat. In the present study, we compared…

(Source: Aviation, Space, and Environmental Medicine)

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Marked pericardial inhomogeneity of specific ventilation at total lung capacity and beyond.
Respir Physiol Neurobiol. 2009 Oct 31;169(1):44-9
Authors: Sun Y, Butler JP, Lindholm P, Walvick RP, Loring SH, Gereige J, Ferrigno M, Albert MS
We measured regional ventilation at 1l above functional residual capacity (FRC+1L) and total lung capacity (TLC) in three normal subjects and four elite breath-hold divers, and above TLC after glossopharyngeal insufflation (TLC+GI) in the divers. Hyperpolarized (3)He MRI was used to map the local ventilation per unit volume over the entire lung. At TLC and above, there was markedly increased regional ventilation of the lungs in the pericardial region compared with the relatively uniform ventilation throughout the rest of the lung. The distribution of fractional ventilation regionally was relatively uniform at FRC+1L, with a small non-gravitational cephalocaudal gradient of specific ventilation in the supine posture. Our observations at high lung volu…

Decompression sickness in breath-hold divers: A review.
J Sports Sci. 2009 Dec 3;:1-16
Authors: Lemaitre F, Fahlman A, Gardette B, Kohshi K
Although it has been generally assumed that the risk of decompression sickness is virtually zero during a single breath-hold dive in humans, repeated dives may result in a cumulative increase in the tissue and blood nitrogen tension. Many species of marine mammals perform extensive foraging bouts with deep and long dives interspersed by a short surface interval, and some human divers regularly perform repeated dives to 30-40 m or a single dive to more than 200 m, all of which may result in nitrogen concentrations that elicit symptoms of decompression sickness. Neurological problems have been reported in humans after single or repeated dives and recent necropsy reports in stranded marine mammals were suggestive of decompression sickness-like symptoms. Modelling attempts have suggested that marine mammals may live permanently with elevated nitrogen concentrations …

Linér MH, Andersson JPA. Hypoxic syncope in a competitive breath-hold diver with elevation of the brain damage marker S100B. Aviat Space Environ Med 2009; 80:1066-8.
Introduction: Competitive breath-hold divers can accomplish previously unbelievable performances; e.g., the current world record for apnea during rest (“static apnea”) is 11 min 35 s. However, whether such performances are associated with a risk for hypoxic brain damage has not been established. Case Report: A breath-hold diver's competitive performance resulted in a loss of consciousness, after which he was subjected to a medical examination by the event physician. Blood samples were collected for analysis of the brain damage marker S100B in serum. The S100B in serum was 0.100 μg · L−1 in the blood sample collected 15 min after the loss of consciousness. At 1 and 5 d after the incident it was 0.097 μg · L−1 and 0.045 μg · L−1, respectively. Discussion: The elevated level of S10…

Authors: Breskovic T, Ivancev V, Banic I, Jordan J, Dujic Z Apnea divers are exposed to repeated massive arterial oxygen desaturation, which could perturb chemoreflexes. An earlier study suggested that peripheral chemoreflex regulation of sympathetic vasomotor tone and ventilation may have recovered 4 or more weeks into the off season. Therefore, we tested the hypothesis that peripheral chemoreflex regulation of ventilation and sympathetic vasomotor tone is present during the training season. We determined ventilation, heart rate, blood pressure, cardiac stroke volume, and muscle sympathetic nerve activity (MSNA) during isocapnic hypoxia in 10 breath hold divers and 11 matched control subjects. The study was carried out at the end of the season of intense apnea trainings. Baseline MSNA...

This study was conducted to determine whether ventilatory parameters would change in breath-hold divers (BHDs) after they performed the glossopharyngeal technique for lung insufflation. Fifteen elite BHDs, 16 non-expert BHDs and 15 control subjects participated in this cross-sectional study. Volumes and expiratory flow rates were measured twice, before and after the glossopharyngeal technique performed at rest. Before the technique, greater forced vital capacity (FVC) and forced expiratory volume in 1_s (FEV1) and lower FEV1/FVC were noted in the elite and non-expert BHDs compared with controls. No difference was noted regarding the other pulmonary parameters. After the technique, increases were noted in FVC, FEV1 and maximal voluntary ventilation in the elite BHDs (P_<&n...