Freediving Leading to Sleep Apnea?

[superhornet59]

I think I can really agree on the "Lower O2 consumption means lower CO2 concentration" theory. I imagine that yes, we are more efficient at O2 use, and as such it takes longer before the CO2 levels reach that unbearable point.

Still very interesting, this changes my perspective on my training a bit...

 

[trux]

I think I can really agree on the "Lower O2 consumption means lower CO2 concentration" theory. I imagine that yes, we are more efficient at O2 use, and as such it takes longer before the CO2 levels reach that unbearable point.

I do not think that anyone ever doubted it. And I would not even call it a theory, but rather a well known fact. However, the reduced CO2 production does not explain why a freediver who can suffer through CO2 contractions for several minutes, gave up in that study at the same level as an ordinary test subject who never tried to overcome urge to breathe for more than couple of seconds. Even with reduced CO2 production, and limited growth of PaCO2 in lungs at prolonged apnea, the stress a freediver needs to pass through at such max attempt, is certainly much higher than at a non-diver who normally interrupts any breath-hold after 30-40 seconds because of discomfort.

 

[superhornet59]

is there any evidence of any temporary changes occurring during a breath hold that don't occur while breathing?

The CO2 levels might be the same either way, but during either a breath hold, or low oxygen concentrations (I'm assuming those High CO2 tests were still done with adequate O2 in the mix), the body could be doing something to increase its tolerance?

The reason I used the word theory is because I haven't read (not that they don't exist, I just haven't looked for them) any studies that suggest that a freediver sitting face down in a pool is burning any less oxygen then an average Joe in a similar relaxed (ie same heart rate and level of physical activity) state.

 

[wet]

I think diaphragmatic contractions are CO2-induced reflex muscle twitches that evolved to stimulate propulsion of the body towards the surface, that act as supplemental pumping mechanisms moving oxygen rich blood towards the body/brain core, equivalent to apneic autonomic rhythmic gasping.

Initial contractions during a dive do not indicate hypoxia, nor danger-level hypercapnea, only higher-than-aerobic-level CO2.

Inhaling CO2-rich air indicates danger-level hypercapnea and acidosis, whether or not accompanied by contractions. The only reaction to that is to respire, whether during a dive or asleep afaict.

 

[wet]

Seals have sleep and dive apnea
Seals' muscles hide a built-in scuba tank - life - 14 October 2008 - New Scientist

AN OXYGEN reservoir within seals' muscles could explain how they can dive underwater for up to 80 minutes at a time without taking a breath. Seal muscle contains 20 times as much myoglobin - a protein that stores and transfers oxygen within their cells - as humans. Seals also stop breathing for 20 minutes at a time while asleep on land, which probably helps them conserve energy.

Walruses have sleep and dive apnea
http://www.msnbc.msn.com/id/29616122/

A new study on the sleeping habits of walruses reveals that these flippered marine mammals are some of the world's most unusual snoozers, since they appear to sleep anywhere, but they may also break the world's record for continuously staying awake.


Apnea sleeping walruses: at water surface with inflated pharyngeal air sac, on sea bottom with deflated pharyngeal air sac, unihemispherically (like dolphins, swimming while half asleep), hanging from icefloes semisubmersed.
AFAIK they never backfloat while sleeping, unlike sea otters.

Sleeping whales & dolphins (see comments): http://www.nature.com/news/2008/080221/full/news.2008.613.html

 

[efattah]

I've done tests with my own CO2 monitor and with training I have been able to withstand 10-11% CO2 in my lungs during CO2 tables. A normal untrained person can't even withstand 6.5% CO2.

I also routinely do breath-holds where I simply inhale and hold, without any breathe up whatsoever, and still can hold to near BO.

So anyone who thinks that trained freedivers have the same resistance to CO2 as untrained people is fooling themselves in a big way.

 

[trux]

I've done tests with my own CO2 monitor and with training I have been able to withstand 10-11% CO2 in my lungs during CO2 tables. A normal untrained person can't even withstand 6.5% CO2.

I also routinely do breath-holds where I simply inhale and hold, without any breathe up whatsoever, and still can hold to near BO.

So anyone who thinks that trained freedivers have the same resistance to CO2 as untrained people is fooling themselves in a big way.

Eric, I suppose you are measuring your venous CO2 saturation, and not the CO2 saturation in alveolar gas. In the study mentioned in this thread, test subjects inhaled CO2 enriched air (without holding their breath). At real breath-hold, after certain threshold, the alveolar CO2 grows very slowly, while the SvCO2 rises quicker. That's why I also wrote the study was not really studying the same effect we experience during apnea, but merely resistance against high alveolar CO2. Despite it, the equal results at non-freedivers and top freedivers, were surprising. And if I remember well, one of the test subjects was Tom Sietas, so we cannot really tell the freedivers were not on a sufficient level.

 

[felipe felop]

in one way or another depending on self your body reacts to different stresses be they air/water,your body deals with it but what about the other way round,the mind must overcome the natural functions/dyssfunctions of what your body tells you first. Primarily it and must be supreme self fitness, diet, measured confidence,small goals set by self, not others, but driven and directed by others with control/knowledge for all of us to progress at an even rate,this function of the mind/body takes a lot of understanding/training outside the realms of self belief,water borne intuity that can take a lifetime to begin to master,do you take time out how to breathe without pressure of water first,because i believe it is taken too lightly by all, as it is a given in 1bar pressure.incorrect, breathe at 0.5 bar then learn again

 

[reason]

I have no clue about the science, but i do know i have found myself dreaming about diving and my wife will attest to me holding my breath in my sleep. I do lump this into behavior like my hound dog chasing squirrels in her sleep. Its just what we like to do.

 

[tuppertn]

This one's been dormant for a while, but I just joined the forum so....BUMP.

CO2 tolerance aside, one thing that concerns me about apnea diving in relation to Obstructive Sleep Apnea (OSA) is the development of pulmonary hypertension (PHTN).

Background:
Patients with long-standing, untreated OSA eventually develop PHTN due to chronic hypoxia. There is a compensatory mechanism in the pulmonary vasculature called hypoxic pulmonary vasoconstriction. It's a normal physiologic phenomenon that reduces pulmonary shunting by locally constricting blood vessels going to areas of the lung that are underventilated (ie-hypoxic). The blood then takes the path of least resistance into areas that are better ventilated. In additons to other things, it helps to compensate for conditions that cause collapse of alveoli in the lung bases--obesity, pregnancy, prolonged bedrest/inactivity.

During prolonged apnea from OSA the entire lung becomes hypoxic leading to pulmonary vasoconstriction on a global scale. Over time (many years) the pulmonary arterioles become fibrotic and stiff creating high resistance in the normally low resistance pulmunary vascular bed--PHTN. Eventually the PHTN leads to right heart failure, ie-the Pickwickian Syndrome.

The Question:
How is freediving any different? If you train yourself to tolerate low O2 levels, dive regularly and over a period of many years are you at risk for a similar phenomenon? Does someone's SpO2 during a 5-6 minute apnea dive just not go all that low? I'm a rank beginner, but mine went to 90% after 2.5 minutes sitting in a chair. That's what got me wondering.

kendall

 

[trux]

Interestingly enough, I have been discussing sleep apnea just a few days ago on the French forum EspritApnee, so have already researched some related studies, and briefly browsed through them.

And so I know that although there are some similarities between sleep apnea and breath-holding, they are in fact two completely different animals, that do not have as much common as one would expect.

There are several reasons for it - first of all, you usually do not perform breath holding each day during 8 hours, with very short recoveries. While during sleep apnea, the O2 saturation drops seriously (i.e. to 60%) and stays on that level for hours, during normal freediving it rarely drops below some 80%, and if so, then just for couple of seconds.

Then, during breath-hold diving, there is the diving reflex that helps to cope with the interrupted air supply. Although at sleep apnea some effect of the diving reflex may be also present, it is quite different than at diving.

And then, although I did not see any study about it, I think we should not underestimate the mental aspect - while breath-hold diving, your brain is well aware of what you are doing, and that you do it voluntarily (emotionally positive). When sleeping, the brain just fights back the lack of air supply (inducing emotionally negative feelings).

So now, let's look at some of the aspects and comparisons between sleep apnea and freediving:

1) Hypertension - the study Central chemoreflex sensitivity and sympathetic neural outflow in elite breath-hold divers -- Dujic et al. 104 (1): 205 -- Journal of Applied Physiology shows that breath-holding does not lead to sustained arterial hypertension as sleep apnea does:

Repeated hypoxemia in obstructive sleep apnea patients increases sympathetic activity, thereby promoting arterial hypertension. Elite breath-holding divers are exposed to similar apneic episodes and hypoxemia. We hypothesized that trained divers would have increased resting sympathetic activity and blood pressure, as well as an excessive sympathetic nervous system response to hypercapnia. We recruited 11 experienced divers and 9 control subjects. During the diving season preceding the study, divers participated in 7.3 ± 1.2 diving fish-catching competitions and 76.4 ± 14.6 apnea training sessions with the last apnea 3–5 days before testing. We monitored beat-by-beat blood pressure, heart rate, femoral artery blood flow, respiration, end-tidal CO2, and muscle sympathetic nerve activity (MSNA). After a baseline period, subjects began to rebreathe a hyperoxic gas mixture to raise end-tidal CO2 to 60 Torr. Baseline MSNA frequency was 31 ± 11 bursts/min in divers and 33 ± 13 bursts/min in control subjects. Total MSNA activity was 1.8 ± 1.5 AU/min in divers and 1.8 ± 1.3 AU/min in control subjects. Arterial oxygen saturation did not change during rebreathing, whereas end-tidal CO2 increased continuously. The slope of the hypercapnic ventilatory and MSNA response was similar in both groups. We conclude that repeated bouts of hypoxemia in elite, healthy breath-holding divers do not lead to sustained sympathetic activation or arterial hypertension. Repeated episodes of hypoxemia may not be sufficient to drive an increase in resting sympathetic activity in the absence of additional comorbidities.

2) Then this study SpringerLink - Journal Article investigates arrythmias at sleep apnea and breath-holding

In conclusion, ectopic arrhythmias were common during maximal static apneas for training purposes. The results indicate that the occurrence of ectopic beats is associated with individual factors such as the tolerable SaO2 decrease.

3) And this document can be interesting for you too Cerebrovascular reactivity to hypercapnia is unimpaired in breath-hold divers

Our findings indicate that the regulation of the cerebral circulation in response to hypercapnia is intact in elite breath-hold divers, potentially as a protective mechanism against the chronic intermittent cerebral hypoxia and/or hypercapnia that occurs during breath-hold diving. These data also suggest that factors other than repeated apnoeas contribute to the blunting of cerebrovascular reactivity in conditions like sleep apnoea.

If you Google the topic, you can find many more interesting documents

 

[tuppertn]

Good stuff, Trux. I've been browsing the subject a little more since posting yesterday. It does appear that duration and chronicity are major factors.

kendall

 

[ploum]

Like reason, I know I'm doing a lot of sleep apnea… because I'm dreaming about freediving. I'm a bit worried about it but I don't think it's really related to the "sleep apnea" medical condition.

 

[michael white]

Wondering how many other free divers experience sleep apnea? I suspect it may be quite often whit increased risk of health.. I can help with that. www.breathing.com/themes.htm

 

[michael white]

A trained freediver can handle very low levels of CO2 (i.e. hyperventilate without fainting), as well as handle high levels of CO2 (>10% in some cases).

Personally, I used my oximeter to check to see if I had sleep apnea, and I did !

I set the alarm to 80% SaO2, and it would wake me up every 5 minutes. I set it for record mode and turned off the alarm. By the morning it had shown that I had desaturated over 50 times, many times to 75% SaO2.

"Personally, I used my oximeter to check to see if I had sleep apnea, and I did !" I study breathing. Sleep apnea is of huge interest. I can help email is mike at breathing.com

 

[michael white]

I believe that logic will not answer the question. I would like to see a poll taken about who free dives and has sleep apnea. I suspect there is a correlation and can help with that with my breathing development but have no clue how i can connect with those who need that information.

 

[michael white]

This one's been dormant for a while, but I just joined the forum so....BUMP.

CO2 tolerance aside, one thing that concerns me about apnea diving in relation to Obstructive Sleep Apnea (OSA) is the development of pulmonary hypertension (PHTN).

Background:
Patients with long-standing, untreated OSA eventually develop PHTN due to chronic hypoxia. There is a compensatory mechanism in the pulmonary vasculature called hypoxic pulmonary vasoconstriction. It's a normal physiologic phenomenon that reduces pulmonary shunting by locally constricting blood vessels going to areas of the lung that are underventilated (ie-hypoxic). The blood then takes the path of least resistance into areas that are better ventilated. In additons to other things, it helps to compensate for conditions that cause collapse of alveoli in the lung bases--obesity, pregnancy, prolonged bedrest/inactivity.

During prolonged apnea from OSA the entire lung becomes hypoxic leading to pulmonary vasoconstriction on a global scale. Over time (many years) the pulmonary arterioles become fibrotic and stiff creating high resistance in the normally low resistance pulmunary vascular bed--PHTN. Eventually the PHTN leads to right heart failure, ie-the Pickwickian Syndrome.

The Question:
How is freediving any different? If you train yourself to tolerate low O2 levels, dive regularly and over a period of many years are you at risk for a similar phenomenon? Does someone's SpO2 during a 5-6 minute apnea dive just not go all that low? I'm a rank beginner, but mine went to 90% after 2.5 minutes sitting in a chair. That's what got me wondering.

kendall

What have you learned since then?

 

[michael white]

Like reason, I know I'm doing a lot of sleep apnea… because I'm dreaming about freediving. I'm a bit worried about it but I don't think it's really related to the "sleep apnea" medical condition.

/
What have you learned since the/n