Never hold your breath, except...

[FlyingSquid]

...except when? In which noteworthy situations it's ok to violate the rule?

What if you meet that breathtaking whaleshark?

 

[warmwaterturner]

When the breath that you are holding was taken at the surface and not from a compressed supply at depth.........

 

[Akimbo]

Somewhere in the 1970s “Never hold your breath while ascending in SCUBA” became “Never hold your breath”. Note that Scuba was an acronym them. There are any number of reasons why, but none are complimentary to students or instructors.

 

[Peter Guy]

OP -- as with so many "rules" one needs to understand the reason for them.

Why is there a rule to "Never hold your breath" while scuba diving?

Akimbo wrote the proper rule.

So, please, explain to all of us why Akimbo's restatement is the correct one. Once you have done that, you have answered your own question.

 

[BDSC]

I'll sometimes hold my breath when I'm doing video, especially if I am trying to get a close up shot.

 

[FlyingSquid]

OP -- as with so many "rules" one needs to understand the reason for them.

Why is there a rule to "Never hold your breath" while scuba diving?

Akimbo wrote the proper rule.

So, please, explain to all of us why Akimbo's restatement is the correct one. Once you have done that, you have answered your own question.

I was going to elaborate on my post, but didn't want to bias the answer. From day 1, I thought that not holding your breath, period, was a safe way to make new divers lose this habit without thinking much. So, just NEVER do it. Easy to remember it like this, without exceptions.

But as far as I could tell also from day 1, there wouldn't be any particular problem if I held my breath while keeping my depth or going down. Although also no particular advantage in doing so either. Of course, it's taken for granted, rightly so, that students would totally suck at controlling buoyancy in their first dives, so better to stick with the "never", period.

I wondered about which situations would actually beadvantageous to do so. BDSC gave an example.

 

[emoreira]

Sometimes I hold my breath when taking photos and I'm pretty near the fish I'm shooting. One thing that you should be sure when holding your breath is that there should be no depth changes during the breath hold.
The second moment when I hold my breath is doing the surface weight check.
Besides those two moments, never, ever.

 

[261311]

Lung over expansion, it's like selling ammo and reminding people not to hunt certain things. There are situations where you may want to, situations where you've exhausted all of your air so in doing so you obviously can't exhale, etc.

One thing I've always wondered, personally- is lung over expansion something you feel immediately (like a pop and you're screwed) or a feeling relative to your ascent rate where you can feel the uncomfortable pressure building and can accommodate by exhaling deeper. I ask this because PADI literature (unsure about others) say to exhale at a rate that sounds like "ahhh" through your regulator. If you're as confused at what that rate is as I am, then good. WHAT DOES THAT MEAN!? My "ahh" isn't the same as the writers. How poorly written.

 

[Lorenzoid]

I can't imagine it's ever a good idea to hold one's breath underwater. Yeah, freedivers do it. Seems to me that ensuring a steady supply of oxygen and release of carbon dioxide has many benefits. Okay, hovering motionless for a photo, you might hold your breath for a second. But I can't imagine PADI or anyone else teaching that it is a fine idea.

261311, I doubt one can always feel an arterial gas embolism occurring. My understanding is that the damage is mainly to the alveoli in the lungs, and that the pressure gradient needed to cause it can be surprisingly low. I cringe when non-divers who did a Discover Scuba dive or something along those lines talk about not wanting to "pop a lung." From what I understand, a lung is less like an impervious sac or balloon than it is like a sponge.

As far as "ahh" is concerned, when your doctor puts a tongue depressor in your mouth and says "Say ahh," my guess is that most people respond by doing pretty much the same thing. How accurate does the rate-of-ahh really need to be? The point is that making a sound while exhaling helps moderate the rate of exhalation (and I'm assuming you're talking about doing an emergency ascent).

 

[Doomnova]

Lung over expansion, it's like selling ammo and reminding people not to hunt certain things. There are situations where you may want to, situations where you've exhausted all of your air so in doing so you obviously can't exhale, etc.

One thing I've always wondered, personally- is lung over expansion something you feel immediately (like a pop and you're screwed) or a feeling relative to your ascent rate where you can feel the uncomfortable pressure building and can accommodate by exhaling deeper. I ask this because PADI literature (unsure about others) say to exhale at a rate that sounds like "ahhh" through your regulator. If you're as confused at what that rate is as I am, then good. WHAT DOES THAT MEAN!? My "ahh" isn't the same as the writers. How poorly written.

I don't think you would feel anything till you burst a lung since the lungs do not contain pain receptors most of the space in the lungs are occupied by alvioli. Honestly thought I'm not about to go and try it out though. I except after the lung goes then the pain would come quite quickly as air floods into your chest cavity and tries to push out that way and or into your blood stream and get lodged where it shouldn't be while expanding.

The biggest reason why not to hold you breath came into play is quite simply the following equation P=pressure V= volume
P1V1=P2V2
your lungs can only expand so much before "pop goes the weasel" The question of when is this happens should depend on the individual. either way going from a higher pressure to a lower pressure(ascent) you do not want to hold you breath as the volume needed by said air will increase risking the pop. Other way around going from low pressure to high pressure (decent) shouldn't have any ill effects. That is not to say holding ones breath is a good thing due to CO2 build up which is a whole other kettle of fish. Now I might pause my breath at a normal lung volume to check my buoyancy but that is about the only time I "hold my breath" and that is to see if I go up or down to then make adjustments as needed to my BCD and Drysuit.