No breathing instruction?

[gcarter]

OK, now let’s define normal. Most people use thoracic breathing on the surface. That would be normal breathing . Thoracic breathing is “bad” breathing for diving.

This is twice now (sort of) you have said this. Interesting. My "normal" has always been gut rather than chest. In working on my breathing and bouyancy, I have been trying to chest breathe, thinking that was the right way to do it. From the start I have been working against my natural breathing tendency.

When next wet I will have to try this approach.

 

[lowviz]

This is twice now (sort of) you have said this. Interesting. My "normal" has always been gut rather than chest. In working on my breathing and bouyancy, I have been trying to chest breathe, thinking that was the right way to do it. From the start I have been working against my natural breathing tendency.

When next wet I will have to try this approach.

The thing that I found to be most useful was being able to reproducibly gauge one's level of lung inflation. If you just fill your lungs, you (at least I) don't have a way to get to the same spot on the next cycle.

-you would be one of the "lucky" ones, go back to what is natural for you. Diaphragmatic breathing is currently considered to be the "best" way to breathe. (buy Steve's book, you won't regret it.)

 

[Thalassamania]

Just to clarify, if I can recall, we were talking on the phone and I think what I suggested was, in the poll ... deep end, to first do the classic weight for neutral at eye level. Then exhale to descend and on the way down, gently inhale to establish neutral. When you hit neutral, stop breathing for an instant, think about where in your cycle you are, and try to keep that as your midpoint. Up a bit, down a bit, up a bit, down a bit, rather than: fill to the top, drop a bit, fill to the top, drop a bit. Now play with that mid point, shed a pound and do it again, shed another pound, do it again, keep shedding a pound till you're breathing comfortably down toward the bottom of your cycle. DO NOT TAKE IT SO FAR THAT YOU ARE UNCOMFORTABLE AND FORCEFULLY EXHALING! I'm told that it is possible, with a forceful exhale, to collapse small airways, trap air behind the collapse and embolize on the way up ... I don't know if that's true, but forewarned is forearmed, ey wot?

Now, when you get this down, depending on the size of your lungs, you'll be able to shift both your buoyancy and your trim by moving the centerpoint of your breath. I'm a big guy, with big lungs, I can shift about 14 lbs. that way. Small women whom I've taught are often in the neighborhood of five lbs. Between sliding my rubber weightbelt fore and aft and shifting my breathing and putting a dash in whatever sort of BC I'm using, trim is a non-issue.

 

[Bubbletrubble]

JI'm told that it is possible, with a forceful exhale, to collapse small airways, trap air behind the collapse and embolize on the way up ... I don't know if that's true, but forewarned is forearmed, ey wot?

@Thalassamania: There is probably some truth to what you've heard, although I've never heard of such a documented case in a real life scuba diver (forceful exhale leading to formation of arterial gas emboli).

In med school, respiratory physiologists taught us that, in the dependent regions of the lungs during forced exhalation, a certain number of small airways (respiratory bronchioles) do collapse, trapping some gas in distal alveoli. This happens at very low lung volumes in normal kids, but it does occur at higher volumes (approaching functional residual capacity) in healthy elderly patients. Bear in mind that the term "dependent" relates to the force of gravity. On land, when we are standing upright, the dependent part of the lungs would be the base. While diving in a horizontal position, the dependent region would refer to a larger region of the lungs (think of the orientation of the lungs). I'm not sure whether the increase in ambient pressure at recreational diving depths is significant enough to amplify such a collapse of respiratory bronchioles during forced exhalation.

For the record, I'm not a pulmonary specialist.

 

[Thalassamania]

Pulmonologist or no, thanks for the consult.

 

[dumpsterDiver]

@Thalassamania: There is probably some truth to what you've heard, although I've never heard of such a documented case in a real life scuba diver (forceful exhale leading to formation of arterial gas emboli).

In med school, respiratory physiologists taught us that, in the dependent regions of the lungs during forced exhalation, a certain number of small airways (respiratory bronchioles) do collapse, trapping some gas in distal alveoli. This happens at very low lung volumes in normal kids, but it does occur at higher volumes (approaching functional residual capacity) in healthy elderly patients. Bear in mind that the term "dependent" relates to the force of gravity. On land, when we are standing upright, the dependent part of the lungs would be the base. While diving in a horizontal position, the dependent region would refer to a larger region of the lungs (think of the orientation of the lungs). I'm not sure whether the increase in ambient pressure at recreational diving depths is significant enough to amplify such a collapse of respiratory bronchioles during forced exhalation.

For the record, I'm not a pulmonary specialist.

I was taught that this is why you don't want to exhale all the air from your lungs at say 60 feet and then just swim up in an emergency. Theoretically, you would not exceed the volumetric capacity of the lungs due to expansion of the resideual volume, but in practice you could embolize because of this effect.