Static PB's

[efattah]

Martin Stepanek is not great at equalizing with air and he had to flood his sinuses on his 90m record. When he was forced to use a mask in Ibiza (i.e. no water equalizing allowed), then he turned at 65m because he said he couldn't equalize.

Herbert and I both use the mouthfill, and that is the only way I could go over 30m on a passive exhale.

Seb Murat, however, uses water all the time; I don't think he ever learned the mouthfill.


Eric Fattah
BC, Canada

[Sebastien]

Hi,

Actually Eric I use both air and water. I have a broad repetoire of equalization techniques depending on the dive depth envisaged, water conditions (especially water temperature and purity) and familiarity with the environment I dive in (with or without mask).

For example, If I think I have enough oxygen to do a dive, i.e., it's anaerobic limited, then I'll use air to equalize and may switch to water if need be; I may even use a mouthfill.

If for some reason on the other hand water purity is an issue I may be forced to equalize on air alone. I may even settle for not equalizing at all if the pressure on my ear drums doesn't exceed much more than 1.2-1.3 atm and the dive is aerobic limited.

In short, my experiences have taught me to be flexible and employ a broad range of techniques depending on where I wish to be physically and physiologically.

On the topic of passive exhale dives, i.e., FRC dives, I'll often do them as I descend, evidenced by a telltale stream of air bubbles. This allows me to equalize with air for a few meters (no mask, no nose plug and still inverted) then use a quick mouthfill (positive mouth pressure and finally mouth volume reduction) before switching to water. This prevents excessive water entering the nasal cavity or Eustachian tubes.....I never let water enter my tubes!

The real reason for exhales is to reduce the energy cost of the descent by using gravity as the propulsive force, since the energy cost of passive drag vs. active drag is about 1/3. The benefit outweighs the corresponding energy cost in ascending, through loss of buoyancy. Free-fall distance varies in direct proportion to my anticipated dive depth. I vary free-fall distance by varying the lung volume and not by adding ballast. I believe the use of ballast to counteract positive buoyancy could be a fundamental flaw in current freediving methodology.

The other reason for passive exhales is to minimize the risk of SWB and DCI during deep dives and promoting an earlier onset and more magnified dive response.

Ivan and others indicated that wet equalization could lead to an increased risk of drowning. As long as as the glottis is shut you wont drown but you might get the sensation of a swollen throat as a result of the osmotic difference between sea-water and throat tissues.To wet equalize correctly, the soft palate must be closed otherwise water will rush in and down.

Sebastien
Townsville, Aust.

[ivan]

hi Seb

Im not really sure on all the tech words but maybe you can clarify a few things for me. Firstly why does water purity affect your diving? do you mean visibility, or sediment in the water.

Also I take it that you fill your tubes with water after a few metres into the descent ?

Why dont you fill them before you descend at all ?

You said you never let water into your tubes, I thought thats exactly what you did so that you dont have to use air to equalise them ?

How does diving on empty lungs help prevent shallow water blackout ?

What is a glottis?

What is osmotic ?

What is a soft palate ?

Lastly how do you fill your equalising tubes with water.

as you can see Im not that smart on tech freediving things and I dont think a lot of others on here are as well.

cheers

Ps Im from Wonga Beach Qld do you know where that is.

[Sebastien]

Hi Ivan,

No worries ......no one is born learned.

Equalizing with water that is high in microorganisms (tropical) could lead to infections if you were to get it in the middle ear. I only fill the sinuses and nasal cavities. Water never enters my middle ears. To ensure this doesn't happen one should have some estimate of one's sinus and nasal volumes. That info. can be gotten in specialist anatomical textbooks. From there you can then work out calculations on pressure volume relations as they relate with depth.

Some might be willing to let water enter the middle-ear, e.g., Stepaneck but the depth limiting factor isn't ability to equalize but ability to tolerate high hydrostatic loads on the venous system and heart muscle, i.e., you could blow a main if blood pressure rises high enough.


You can reduce the risk of SWB by reducing your initial lung volume. As you know they call it shallow water blackout happens (usually) in the last few meters where the pressure gradient is steep. For example, in ascending from 10m to the surface your lung volume will roughly increase two twice the volume. Lung gas must re-expand and/or be 'sucked' out from the circulation for this to happen. If your initial lung volume is say, 4 liters at 10m then by the time you reach the surface this will have expanded to roughly 8 liters, i.e., twice. The greater the change in volume the greater the potential suction effect. If the change in volume is great enough enough O2 could be removed from the circulation to drop arterial oxygen pressure. Now, if the change in volume is small as for example when doing an exhalation dive then so too will the suctional effect.


Glottis is that part of the anatomy which blocks air moving from mouth to lungs and vice versa; as when you hold your breath. The soft plate is that part which opens and closes when you breathe, or not, through your nose. Osmosis is to do with solutions and their concentrations such that the constituent of a solution seek to move from areas of high concentrations to areas of low concentrations and thus gain balance, e.g., pruning effect of the skin when you've been in say, fresh-water too long.


If it still doesn't make sense and if your in Cairns on Thursdays I'm usually at the Woree pool from 11.30am onwards. Feel free to drop by or give us a call the night before (Tel: 40 511150) so that I can confirm that I'll be there. Don't know what you know or don't know but if you feel you might get some benefit from doing a no nonsense session with me, feel free.



Seb
Townsville, Aust.

[Erik]

Obviously a decent dude as well as a champion, this guy Sebastien
Very good to have your input here!
Cheers,
Erik Y.

[efattah]

Personally I think the passive exhale dive gets its main benefit from reduced narcosis & DCS risk, as well as reduced effort during the descent.

I think it is deceptive to say that it reduces the chance of shallow water blackout -- true, but only because it makes deep water blackout more likely.

During an inhale dive, blackout typically occurs in the last 15m -- where the safety freediver is waiting. During an exhale dive, there is no reason to believe the blackout will occur at the end -- it could occur at 30 or 40m if the diver overstepped his limits -- and for most divers, diving with one or two safety freedivers only, there isn't anyone down at 40m to drag them back up.

However, the risk of blacking out at the absolute bottom (60m+) is minimized, due to decreased O2 toxicity & decreased CO2 narcosis... although the extreme negative pressure might cause a blackout...


Eric Fattah
BC, Canada

[TMcKee]

Well, couldn't you take the lesser of two evils and do a full lung dive but exhale quickly in the last 15m to 30m? I don't know...Im just asking. Would this work? I've always seen that pic of kirk exhaling on his way up...

Just wondering..

[JimGlynn]

Sebastien-
Great to have your input. I really like your monofin style. Do you have any videos on the web? I remember seeing a dynamic video last yr. but I cannot find it anymore.
Jim

[Sebastien]

True Eric: reduced narcosis, O2 tox and DCI are important (I think I may have alluded to that previously elsewhere).

When you are referring to a deep black-out due to extreme negative pressure are you referring to extreme vasoconstriction and concommitant increase in arterial CO2 partial gas pressure? If so, my stand on that is that arterial CO2 uptake is reduced because circulation is reduced to central organs. In addition I feel there might be a significant depression of central organ metabolism, e.g., bradycardia, reduced brain temp. Furthermore, the high increase in haematocrit (splenic emptying) and reduced N2 reduces the negative effects of CO2 in the blood through the 'haemoglobin diluting effect'.

The danger I think lies in in the intense vasoconstriction and associated shift to anaerobiosis in prime movers --> plenty of oxygen to maintain consciousness but none to propel the body back-up. On the other hand, there may be a hidden mechanism which modulates muscle oxygen supply so as to strike the best possible balance in energy conservation. In other words, the aerobic limit varies according to effort not just vasoconstriction and hence depth.

Ofcourse a hypoxic episode could occur during descent but unlikely due to the increase in ppO2, despite low lung volumes.
As the dive progresses and the blood shift increases pulmonary shunting increases, i.e., pulmonary bypass through the Thebesian circulation such that gas exchange is impeded. If gas exchange is very much reduced this would create a significant difference between alveolar and arterial ppO2 such that O2 is stored, becoming re-available during the re-expansion (ascent) phase.


Bottom line: speculation and conjecture.
Best knowledge is first-hand experience.


PS: Jim, try www.amphibios.info


Available next thursday
Sebastien
Townsville, Aust.

[ivan]

hi Seb

Wow are you in the Cairns pool every Thursday if so for how much longer. Like I said im from Wonga beach so im about 100km north of you but If I can find some time I will definetly give you a ring. It would be so cool to meet someone who knows what you mean when you say freediving, yep Ive never met anyone who freedives without a gun.

BTW way I dont think I could do your training im not a good diver, but I would like to watch you train maybe if thats alright. Maybe I will get to see a monofin in real life. I work usually from 8 or 9 pm till 12pm but maybe I will get a couple of days off work.

cheers

[ivan]

hi Seb

Ive been thinking hard and planning a way to get there. I think I can maybe get there this thursday if your there. The only problem is I dont own my own car so I might have to be VERY NICE to my parents so they should lend me there car. How long are you training for. I will Pm you also cos people may get angry if I keep asking you questions.

cheers

[A Brownsword]

Wow, this discussion is certainly pushing the envelope on my knowledge of physiology! I'm particularly interested by this statement, however:

Originally posted by Sebastien
The real reason for exhales is to reduce the energy cost of the descent by using gravity as the propulsive force, since the energy cost of passive drag vs. active drag is about 1/3. The benefit outweighs the corresponding energy cost in ascending, through loss of buoyancy. Free-fall distance varies in direct proportion to my anticipated dive depth. I vary free-fall distance by varying the lung volume and not by adding ballast. I believe the use of ballast to counteract positive buoyancy could be a fundamental flaw in current freediving methodology.

Obviously this is what aquatic mammals do as well since we're the only ones silly enough to carry around lead weights. May I ask what depth you weight yourself to be neutral at then? And do you vary it at all, when changing your diving suit or switching from fresh to salt water, for example?

One nice thing about weights is that you (or your buddy) can drop them with the advent of a problem. On an exhale dive you have no ability to improve your bouancy.


On the subject of exhalation during the last part of the ascent (as the photo of Kirk shows, and I believe he recommends in his courses), this obviously relieves the problem of chest pressure due to expansion... but what effect does it have on the O2/CO2 partial pressures? Is such an exhalation during the last 10m or so going to convince your body that it has to breathe more or less urgently?

Thanks for the great discussion.

[TMcKee]

Originally posted by ivan
hi TMckee

I have never thought of what you just said and it kinda makes sense. Are you saying that in the first 33ft of the dive that this is when I will be using most of my precious 4L of air. SO once you start getting past 33ft you shouldnt have to waste so much air equlising. Can you tell me a little more about this please.

Zipy yeah 100ft is more like it

cheers

Typically the biggest pressure change is between 0 - 33fsw. I found that in a decompression chamber or diving deeper usually didn't require much clearing. Correct though, after 30fsw or so, you shouldn't have to equalize quite so often.

[cdavis]

Hi all, fabulous discussion

Just to add an historical example, pearl diving was a big thing in polynesia before WWII, no fins, crude masks, down with a big rock, not sure how they got up. Several reporters at the time, some eyewitnesses, report dive times of 3-4 minutes, depths of up to 45m, commonly 36m. What is really interesting is the description of the divers going down with only half a full breath and begining to exhale on the bottom, half way through the dive, and continuing to exhale until they surface. Any comments from the experts? Has anybody tried anything like this?

[Sebastien]

Reply to: A Brownsword

May I ask what depth you weight yourself to be neutral at then? And do you vary it at all, when changing your diving suit or switching from fresh to salt water, for example?

One nice thing about weights is that you (or your buddy) can drop them with the advent of a problem. On an exhale dive you have no ability to improve your bouancy.

On the subject of exhalation during the last part of the ascent (as the photo of Kirk shows, and I believe he recommends in his courses), this obviously relieves the problem of chest pressure due to expansion... but what effect does it have on the O2/CO2 partial pressures? Is such an exhalation during the last 10m or so going to convince your body that it has to breathe more or less urgently?

That will vary with the type of dive I do; I have no fixed recipe.
That being said, I'm approx. 1.5kg -ve at the surface at FRC (wet) without a wetsuit in seawater. I'm fortunate enough to be diving at present in 29 degree Celcius in the ocean at the moment so wearing a wetsuits isn't an issue presently.

I've never dived in freshwater and so have no opinion on that.

For me this issue of neutral buoyancy is irrelevant. I only seek to reduce effort at the surface by being positive whilst breathing and negative whilst diving. One of my aims is to minimize buoyancy changes. I cannot increase +ve buoyancy greatly whilst ascending but that's ok as I'm prepared to work anaerobically if I have to.

Kirk may be be purposefully exhaling on ascending if his aim is to improve venous return during the final few metres. Buccal pumping could prevent adequate venous return and result in loss of consciousness.


Reply to Ivan of Wonga Beach:

It doesn't matter if you can't do my training, sometimes I can't do it too....intent and attitude is much more important I think.
Try me on 47 240 019 (Townsville) if you can't get me in Cairns.



Sebastien Murat
Townsville, Aust.