Breathing

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WKenny

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Location
Chicago, Illinois
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Recently, several divers were discussing proper methods of breathing to conserve air. We covered the basics of inhaling slowly and fully from the diaphram; a momentary pause after inhaling; and exhaling slowly. One of the divers suggested that exhaling slowly through the nose, instead of through the mouth, was a good method to conserve air because the exhale was slower through the nose than through the mouth. He also said that he did not experience a mask leak when exhaling through his nose. Does anyone have any comments or opinions regarding whether this method of exhaling through the nose has any merit in extending the bottom time?
 
Does anyone have any comments or opinions regarding whether this method of exhaling through the nose has any merit in extending the bottom time?

Yes. It seems quite silly.
 
Whatever 'trik' you'll do, the gain will be marginal (if any). Just relax, and the SAC will decrease with experience eventually. And you may always get a bigger tank if your dive requires it.

Let's say your SAC is 25l/min. The "trick" will get you to 20l/min (highly doubt it). Then at 20 meters you'll use 40l/min instead of 50l/min. From a 15L tank, using 150 of 200 atm, then you'll stay 56 instead of 45 minutes (counting all as bottom time, to simplify). At 30 meters you'll use 60 instead of 75l/m, which means 37 minutes instead of 30 minutes. Even this imaginary huge SAC decrease provided a marginal gain (but as it wasn't natural for your breathing, probably the discomfort wasn't worth it).

It's like when you drive on the highway at a mad speed but doing the basic calculus you'll discover you gained ~15 minutes on a 2 hours trip, while risking your life for almost nothing. Here, an unnatural breathing pattern might get you drowned from CO2 poisoning)
 
Breathing to conserve air is like pushing a rope. It's trying to do things the wrong way around.

Learn to be quiescent in the water, able to effortlessly hover neutrally buoyant in the water without any extraneous flapping, and learn to slow down. Minimizing motion reduces the amount of calories you burn, reducing your CO2 generation, reducing your gas consumption. Learn to be relaxed and calm underwater without worrying about things (like your breathing). Reducing your stress level will also reduce your gas consumption. Wear sufficient thermal protection to be warm (but not overheating). By losing less heat to the water, your body will not need to burn as many calories just to try to keep warm, and with fewer calories used, you'll have less CO2 generated to breathe out.

Trying to reduce your gas consumption by concentrating on your breathing does nothing for your physical exertion level or heat loss. Unless it *vastly* reduces your stress level (and it may increase it, if you're really trying to breathe "correctly"), you won't be generating any less CO2. If you're breathing less and generating the same amount of CO2, it naturally follows that you are retaining more CO2 by your efforts.

Elevating your CO2 level by trying to force your breathing makes you more susceptible to oxygen toxicity, it contributes (perhaps strongly) to narcosis, and it's likely to give you some *royal* headaches. It's just a bad idea. Far better is to concentrate on the things that generate CO2, as when you reduce those (slow down, fix your buoyancy and *especially* your trim, wear the wetsuit) your body will naturally breathe less and your dives can relax into longer times without any buggy whips or spurs necessary.

Breathing is a sign to be read, not a skill to be learned.
 
Buoyancy / Trim / Weighting will have a tremendous impact on gas consumption. Another thing that I've found helps a lot is having an objective. When you focus on an objective you tend to naturally relax.

For instance, find a local species of life that is rare or hard to find. Spend the entire dive slowly, methodically searching every nook & cranny.
 
just dive more and it will come... once you are trim and neutrally buoyant you'll notice more gas in the tank after a long dive. (not only that, it seems that the more you worry about it, the worse it gets) Breathing is just that BREATHING...no "triks" will help.

Like Vixtor said, get a larger tank! If you are finding that you are the first one to call the dive and you are all diving "80's" get a "95" or larger and you'll hit the curve. When I stopped worrying about it, it got better!
 
Not only do I agree that it's silly, but I disagree with the claim that it doesn't cause mask leaking. I know (for me, at least) that when I'm conscious of my breathing and make sure that I only exhale through my mouth that my mask doesn't leak....but toward the end of the dive, and especially if I'm getting cold, I start paying less attention to my breathing, which results in exhaling through my nose. I get a big bubble in my hood and a decent amount of water pooling in my mask.

As has been mentioned multiple times, figuring out buoyancy and becoming more relaxed in the water help air consumption significantly. I wouldn't work on silly little tricks to get better air consumption....focus on inhaling and exhaling fully (and not skip breathing) and things will get better quickly.
 
Even if the mask doesn't leak, exhaling through the nose may present problems. You're pumping lots of warm moist air into the mask, and it's likely to increase fogging, especially in cool water.
Your exhale rate is determined by the diaphram and it should be easy to exhale just as slowly through the mouth.

Overall, I agree with Clayjar. If you focus on the causes of high air consumption, the breathing rate will drop naturally in response to lower oxygen demand and CO2 output. Moreover focusing on managing the breathing rate risks breathing less than your body requires and can lead to increased CO2 retention.
 
Hmmph, all of you are mouth breathers?

I probably exhale 30-40% of the time through my nose -- more towards the end of the dive BECAUSE it is warm air and it gives me just a little more heat (or, more correctly, I lose a little less). It also has the added benefit of constantly "clearing" my mask which compensates for whatever annoying mustache leak might exist (which it does all too often).

Does it extend my BT -- I don't think so. It's just part of my normal breathing pattern. I was actually thinking about this on my way up from feeding horses this morning. Above water I apparently do the majority of my breathing through my nose, not my mouth. It is thus "unnatural" for me to breathe in and out through a reg.
 

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