I don't understand: breathing deeply and using breathing for buoyancy control seem to contradict each other

[landphil]

As a beginner OW diver, it’s all kind of a progression- first, get comfortable enough that your breathing underwater is normal. That means not heading towards excited hyperventilating or doing some weird special breathing to try to game your air consumption. And as a bonus, all of that just comes with diving more, as you stop doing water aerobics with your hands and can just relax without focusing on your breathing.

The second piece that comes with more diving is knowing when you have the right amount of air in your BC/drysuit. Once you’ve tuned your buoyancy for your depth, a deep inhale and slow exhale starts you moving up, while a deep exhale and slow inhale starts you moving down. If one of the directions doesn’t work, you need to adjust the air in your BC. And if your BC is inflated right, normal breathing won’t be deep or shallow enough to change your depth. The quickest way to dial this in is to dive in warm water with minimal exposure gear, which for us cold water divers is another bonus- tropical vacation diving

 

[sea_ledford]

So this means I should not be breathing full lungfuls in and out but rather only 20% - going from 40%-60% or 65%-85%? That is not what I thought. I thought the ideal is to go from close to 0% to 100%? Is that wrong?

Look at random search result I now understand a bit more about the difference between the lung capacity after forcefully breaking in/out compared to normal in out. Given that, it looks like you are saying that I should be breathing a normal tidal volume, not deeper in or out than that? Maybe that is my misunderstanding.

Correct, normal tidal volume, which is about 0.5 L in an adult male. Pay attention to how much you are breathing during a leisurely walk. Your scuba breathing under a normal, non stressed situation should be about the same. The only time you'll use even close to full tidal volume is under very high aerobic work, like sprinting as fast as you can go for 30 to 60 seconds. That would be called vital capacity, and is about 4.5 L in an adult male. Although when I had my vital capacity measured last, I was close to 7L, so quite a bit of variability in there.

Depending on you body size and lung volume, you can easily adjust 4-6 lbs of weight change with relatively normal breathing patterns. If you were doing as full of a breath as possible, you'd be looking at something like 10 lbs of buoyancy shift (4.5L = 0.1589 cuft x 64lbs/cuft=10.2 lbs)

 

[FreqFlier]

A lot of great tips in this tread.

Few too many divers simply forget (or don't even know) that the most efficient O2 exchange happens in the lower part of our lungs. Hence diaphragmatic breathing comes into play. Two main benefits - better SAC rate and lesser impact on buoyancy swings. You can google the rest

 

[happyharris]

A lot of great tips in this tread.

Few too many divers simply forget (or don't even know) that the most efficient O2 exchange happens in the lower part of our lungs. Hence diaphragmatic breathing comes into play. Two main benefits - better SAC rate and lesser impact on buoyancy swings. You can google the rest

Breathing with the diaphragm is another thing that seems like an unconscious skill that people don't know how they do, and don't know how to explain. I do not have any more conscious control over my diaphragm than I do over my heart. In addition, whether I move my diaphragm or my ribs, the air is going to come in through the mouth, down my throat, through the trachea, then the bronchi, etc. I imagine that something is being done differently by people who talk about breathing with their diaphragm, but I wonder what it is.

 

[Lorenzoid]

Breathing with the diaphragm is another thing that seems like an unconscious skill that people don't know how they do, and don't know how to explain. I do not have any more conscious control over my diaphragm than I do over my heart. In addition, whether I move my diaphragm or my ribs, the air is going to come in through the mouth, down my throat, through the trachea, then the bronchi, etc. I imagine that something is being done differently by people who talk about breathing with their diaphragm, but I wonder what it is.

My wife who is not only my dive buddy but also teaches voice (that is, singing) apparently routinely describes that sort of breathing technique involving the diaphragm to her students. Maybe it helps her in diving, too, but for me that degree of detail is way more than I need to know. I believe some of it is simply trial and error. If you're yo-yo-ing more than a couple of inches, it's too deep, so back off. If you're getting headaches or otherwise not feeling quite right, it may be too shallow, so breathe deeper. Play around with it.

 

[Nosmosis]

I am confused about how using breathing for buoyancy control interacts with breathing deeply to be efficient with air usage.

In my training dives I found that I was eventually able to stay in a relatively still horizontal position, without flapping my arms and legs around. However, when I took a deep breath in, I would go up, and when I breathed out again, I would go down. The only way for me to stop yoyo-ing up and down was to take small breaths in and out. The problem with that, of course is that it's a really inefficient use of air, due to dead space. The advice I see is to take deep breaths in and out (4, 5, 6 seconds each).

Could people help me see what I am missing here? How do I breath in and out deeply, without yoyo-ing up and down?

There is a great part in Technical Diving by Mark Powell that talks about this and provides good diagrams that are excellent for describing the answer to this question.

 

[happyharris]

My wife who is not only my dive buddy but also teaches voice (that is, singing) apparently routinely describes that sort of breathing technique involving the diaphragm to her students. Maybe it helps her in diving, too, but for me that degree of detail is way more than I need to know. I believe some of it is simply trial and error. If you're yo-yo-ing more than a couple of inches, it's too deep, so back off. If you're getting headaches or otherwise not feeling quite right, it may be too shallow, so breathe deeper. Play around with it.

I have heard singers talk about that too, in the same way. I think it is the same issue. Something other than just "breathing with the diaphragm" is going on but the people who know how to do it are unable to describe what they are doing.

I think it's similar to equalizing ears. I am able to just open my Eustachian tubes at will to equalize (lucky me). I rarely need to try any of the tricks like yawning, moving lower jaw, swallowing, turning my head, etc. I can just do it. However trying to describe to someone else how I do it is really hard. Same with the diaphragm (if that is really what is happening). Maybe some people actually have conscious control of their diaphragm. I don't and asking me to use it is like asking me to to slow down peristalsis or only use my left nostril. Can't do it.

 

[Chavodel8en]

You should breath steadily, slowly & deeply most of the time, and yes, you will go up and down, but generally this is not a big deal. Just make sure you don't touch the bottom (if you are, you may need to add a puff of air to BC).

This is assuming you are at depth, where yo-yoing is not a big deal. If you are in shallow water, too deep a breath and you will yo-yo yourself right to the surface. So you may need to control your breath more when shallow. But at depth, breath as deeply as you like.

Use your lungs for buoyancy control ONLY when you are intentionally trying to move up or down. And then go back to regular deep, steady breathing. So not a contradiction. Different times/circumstances call for different breathing.

Edit: I think people who caution against yo-yoing should qualify that they mean yo-yoing is a problem when shallow. When you're deep enough, there is nothing wrong with yo-yoing, its a natural result of breathing. If you breath slowly, it will be lessened, but there is no reason not to breath deeply at depth.

 

[Edward3c]

The reason behind breathing advice to new students stems from the use of snorkels, which used to be taught before scuba. If you shallow breath the air in your bronchial tubes, mouth, and snorkel would be breathed in again meaning little, if any, fresh oxygen would get to your alveoli. A few cycles and the amount of O2 in the rebreathed air is insufficient to keep you conscious. The same principle of dead air can be applied to the 2nd stage, in place of a snorkel.

It’s more important you get properly oxygenated air than worry about slight changes in buoyancy.

 

[dmaziuk]

Breathing with the diaphragm is another thing that seems like an unconscious skill that people don't know how they do, and don't know how to explain. I do not have any more conscious control over my diaphragm than I do over my heart.

Try taiji. Or yoga meditation or more or less any Asian martial art, but taiji tends to get you there faster -- meaning abdominal breathing, not the ability to stop your hart on cue.