negatives and contractions

[hteas]

At present my static training consists of negatives twice a week. I feel like they are better for spearfishing or recreational diving, since I reach the point of desperation much more quickly, and can do more of them during a lunch break training session. I exhale to start, then exhale any residual air every 5 seconds for the first half minute, then hold for a long as I can. Recoveries are 60 seconds. I'm sitting at my desk, so there is little danger of BO or LMC, except in the minds of co-workers.
One thing about the negatives that surprises me is that I get a lot of body rushes during breathholds from physiological adaptations and the CO2 reflex, but I never get contractions. On full lung breathholds I typically get my first contraction at 2:30 to 3:00, but have never had one doing negatives.
Anyone else notice this?
Howard

[naiad]

I also don't get proper contractions with negatives. I think others here have noticed the same.

There is probably still a risk of BO and LMC. These can strike without warning, particularly during empty lung apnea.

I started a thread about dry apnea safety, with some tips on how to train safely.
http://forums.deeperblue.net/safety/...ea-safety.html

[cdavis]

Exhales train low 02 tolerance, but don't do as much for co2 tolerance. With little extra 02 in the lungs and less than full blood shift, you're blood 02 level drops very fast doing exhales. You can see it clearly on an 02 meter. Given the right opportunity, you can make the nurse completely crazy with the reading on those meters; she'll think you're dead. Naiad's right, a BO on exhale is very possible. Don't fall out of your chair. I think the contraction thing is individual, I definitely get them, much more uncomfortable on exhale.

Connor

[naiad]

When I get normal contractions, they are like trying to breathe out, but when I get contractions on exhale, they are trying to breathe in. They happen more in dry negative statics, and hardly ever in the pool. They feel much worse than normal contractions, which is why I don't do negative statics very often.

It also scares me to have to actively stop myself from breathing in water. If I blacked out, it would probably be the first thing I do.

[hteas]

I agree with the safety issue. I never do empty negatives in the water.
On land they can be kind of fun. My wife is a nurse for my doctor, and she hates it whenever she checks my pulse. She never knows whether she'll find one.
I guess I'm lucky on the lack of contractions. Sounds like I wouldn't want them. ; )
H

[fflupo]

guys have a good look at this:

www.sub7seas.com

freefall the abyss
wolf

[naiad]

Thanks for the link, fflupo.

Sebastien Murat's method is very interesting, and backed up by a lot of scientific explanations.

However, I still have my doubts about the safety of exhale diving. The issue of water entering the lungs during a blackout or LMC is one of the things that concerns me. Another is negative buoyancy. I am very buoyant with full lungs, but negative even at the surface on full exhale. This would make getting to the surface that much more difficult in case of trouble.

[hteas]

Naiad,
Your comments bring up another training technique.
I do dynamics with partially full lungs. I become neutrally buoyant by exhaling until I can swim without having to fight to stay down. I do repeats of 25 m on the bottom followed by 25 m on my back on the surface for recovery. They're very conservative, but if I ever did push too hard, I guess I'd just float there. Seems a little unnerving. Anybody else train the same.
No, typically no partner-I have yet to find a reliable one, so my choice is to train conservatively or don't train.

[harbour seal]

Originally Posted by naiad

Thanks for the link, fflupo.

Sebastien Murat's method is very interesting, and backed up by a lot of scientific explanations.

However, I still have my doubts about the safety of exhale diving. The issue of water entering the lungs during a blackout or LMC is one of the things that concerns me. Another is negative buoyancy. I am very buoyant with full lungs, but negative even at the surface on full exhale. This would make getting to the surface that much more difficult in case of trouble.

it seems to me that you are mixing two quite different things together:

1 - negatives - this refers to forceful exhale(s) before breath holding, leaving the lungs close to residual volume (depending upon how much air you actually exhale). this can create negative pressure in the lungs as the pressure in the lungs can be below ambient. negatives are quite often used during warm up to help strengthen blood shift and can assist with depth adaptation.

2 - exhale diving - this refers to doing a passive exhale prior to breath holding, leaving the lungs at ambient pressure or functional reserve capacity during the hold. this style of diving is also called frc, seal or e (empty) diving. this is the style of diving pioneered by sebastien murat, among others.

Image:LungVolume.jpg - Wikipedia, the free encyclopedia


contractions due to carbon dioxide build up are nearly impossible with empty lungs during negatives. any contractions experienced are likely due to low oxygen levels.

as far as buoyancy, when diving the frc style the idea is to be able to sink in a passive fashion from the surface. the descent essentially becomes a static, which conserves oxygen until ascent (when the dive response is much stronger). comparing only the last part of the ascent it may seem more difficult to get to the surface using the frc style than full lungs due to the negative buoyancy; however, sebastien murat's findings consistently demonstrated that a diver returns to the surface with HIGHER partial pressure of oxygen in the lungs when using the frc style than with full lungs.

i may be mistaken, but i do not think there is more of a risk of water inhalation during exhale/frc diving than f (full lungs) diving; however, a diver's lungs will hit residual volume at a shallower depth given the lower starting lung volume. the pressure on the lungs at various depths will also (initially) feel greater using the frc style versus full lungs, and time for adaption is necessary to avoid lung squeeze.

finally, negatives should be performed with extreme caution as water inhalation after black out may be possible (due to the negative pressure---vacuum effect). in addition, it is easy to replicate the pressure of very deep dives and thus cause lung injury, if not properly adapted. i have read accounts of numerous experienced divers who have injured themselves while doing negatives.

more experience frc divers feel free to jump in here

cheers,
sean
vancouver, canada

[cdavis]

The extreme ease of getting down sold me on exhale diving, it is so deliciously easy, slowly learning how. Wish I could take Murat's course.

No contractions when doing negatives has got to be an individual thing. I get them. Just tried it, no warm up, full exhale, sitting down, first contraction in 35 seconds, feels just like c02, but more uncomfortable, can't endure very many and start feeling what I think is hypoxic around 50 seconds. Any idea why some do and some don't? Amount of residual volume?

Connor

Connor

[hteas]

Sean,
You state that contractions are nearly impossible with negatives. Is that an assumption or do you have any information you could share?
By the end of a 120 second negative (my best) I have been assuming that the concentration of CO2 in my blood is pretty high, but may be wrong. if you are right then the training is all based on hypoxia. I've been assuming that it was a hybrid with some aspects of both hypercapnia and hypoxia, since I limit breathing to 60 seconds between holds.
Howard

[hteas]

Connor,
I don't know how anyone else does it, but I breathe out whaat little is left every 5 seconds for the first 30 seconds in an effort to make it consistent, and to speed up the reflex by emptying my lungs as much as possible without resorting to negative packing. Right or wrong, I worry that negative packing is the best way in the world to tear your lungs loose from the pleural cavity, so I keep well away from it.
The variability is beyond me. I know some days I never get past 60 seconds, and on a few I do multiple 120s. Since I can't figure me out, I have no clue about anyone else. ; )
Howard

[harbour seal]

Originally Posted by hteas

Sean,
You state that contractions are nearly impossible with negatives. Is that an assumption or do you have any information you could share?
By the end of a 120 second negative (my best) I have been assuming that the concentration of CO2 in my blood is pretty high, but may be wrong. if you are right then the training is all based on hypoxia. I've been assuming that it was a hybrid with some aspects of both hypercapnia and hypoxia, since I limit breathing to 60 seconds between holds.
Howard

actually, no. i said that contractions due to carbon dioxide are nearly impossible with negatives.

to my knowledge, contractions can be caused by either high carbon dioxide levels or very low oxygen levels. in the case of low oxygen, contractions often feel more intense/urgent or are accompanied by a feeling of panic. these factors make them much more excruciating to endure as colin so aptly described.

the length of time you can hold a negative will greatly depend upon how much air you exhale before starting. the amount of air you can exhale will increase with practice as well. many people even do a series of reverse packs to further empty their lungs prior to doing a negative breath hold. look for some excellent descriptions of this and associated yoga techniques from will here on db (william trubridge). prior to a negative i do anywhere from 5 to 9 forceful exhales, the last half of which are only mouthfuls of air (reverse packs). leaning over and gently pressing on your diaphragm as you exhale can help decrease the volume of air left in your lungs.

as far as training hypercapnia, in my opinion negatives (forceful exhales) will not lead to particularly high levels of co2. although, i guess combined with short recoveries, this might allow co2 to build up over repeated holds.

one way of training both hypoxia and hypercapnia is to combine oxygen and co2 tables into one table. the table would have both a hold of increasing duration AND less ventilation time between successive holds.

howard, as a middle ground you could try using a passive exhale (instead of forceful exhales) to complete this kind of combined o2 and co2 table. this would allow you to reach hypoxic levels faster than with full lungs but also allow more opportunity for co2 to build up than with completely empty lungs.

as always, more experienced divers (or anyone for that matter ) please feel free to step in here.

cheers,
sean
vancouver, canada

[harbour seal]

Originally Posted by hteas

Connor,
I don't know how anyone else does it, but I breathe out whaat little is left every 5 seconds for the first 30 seconds in an effort to make it consistent, and to speed up the reflex by emptying my lungs as much as possible without resorting to negative packing. Right or wrong, I worry that negative packing is the best way in the world to tear your lungs loose from the pleural cavity, so I keep well away from it.
The variability is beyond me. I know some days I never get past 60 seconds, and on a few I do multiple 120s. Since I can't figure me out, I have no clue about anyone else. ; )
Howard

although i know they feel excruciating, i don't think this kind of self-inflicted damage is possible (at least under normal conditions).

in order to train empty lungs and diaphragm stretching and control certain yoga postures can be very helpful. one is called uddiyana bahdha, which is an abdominal lock. do some research and reading before rushing into it and allow lots of time for your body to adapt before pushing (don't just copy the video below).

self-inflicted barotrauma is unlikely at normal ambient air pressure; however, it is more than likely when combined with the added pressure caused by increasing depth, especially without appropriate time for adaptation. negatives done in the water can and do cause lung injury if not approached cautiously.

howard, the variable negative breath hold times you describe are likely caused by starting with differing amounts of air (assuming other more obvious factors were held consistent, such as time elapsed since last eating).

YouTube - YOGI Sumit Saadhak Practicing pranayama...

as an example, here someone doing uddiyana bandha and nauli kriya

cheers and enjoy freaking people out with your developing vacuum belly technique,
sean
vancouver, canada

[laminar]

Couple of thoughts:

1. Once I learned to dive FRC, I've felt much safer due to the energy conservation for most of the dive and because my first action at the surface is to inhale fresh air, not exhale first and then inhale. Getting that first breath is so important if you are on the edge. But, I've never been on the edge with FRC simply because diving this way forces you to be very careful with your oxygen consumption and mindful of diving technique. I think FRC makes me a better diver not only for performance but for safety. And I find it easier on my lungs - I haven't had any sort of lung squeeze since I started - and much more enjoyable. But it does take some time to learn it. I am happy that FRC has lead me to longer and more enjoyable dives than by inhaling - it just takes more practice.

2. I question the use of full negative pressure dives for recreational divers and for most competitive divers. I believe they are dangerous and too easy to do for divers who don't yet have the body awareness to do them safely and even for those who should do. I never use them anymore. I find FRC much more effective and gentle at preparing the body for deep dives. I think if you want a strong dive response, lose the wetsuit.

3. The big "thing" about training, for lack of a better word, is intensity and specificity. I've written this before on this forum, but I think for most people, CO2 and O2 tables are not intense enough for competitive training. Now if you simply want to prepare for a season of recreational freediving, I think that FRC statics are much more useful, preferably on the bottom of the pool with a buddy to learn how that works for you at different intensities. Be as specific as possible. Personally, I don't pool train anymore and prefer to swim in the ocean and go freediving as often as possible for my training because I'm aiming to improve over years and years. I think trying to get significantly better over days or weeks is too risky for me.

Mind you, I do have the benefit of having trained intensely years ago and been through all that. But if someone came to me and wanted to become an excellent freediver, I would go about it in a vastly different way. I would make it much more enjoyable, for starters. I can outline my approach if anyone is interested, although it would of course depend on your personal goals and preferences.

Howard, I think putting yourself through exhale statics is perhaps valuable only in experiencing what that feels like. I'm not sure that it will have a direct impact on your diving. Remember that while Will Trubridge does incredible exhale statics, there is a lot more to diving deep and long. I'd say it's not necessarily a direct link to his excellent performances.

Pete