holding breath on scuba

[Danny Valerio]

They teach you never to hold your breath on scuba but I've been wanting to get closer to fish and was wondering if the following would be safe:
-holding breath on exhale: I can exhale all my air and still hold my breath for about 30 seconds before needing to inhale again
-holding breath on descent: I see some fish below me and hold my breath to get closer to them but breath out before heading back up

The only reason I see for not holding your breath is that on the way up the air expands and can cause an embolism. So one should be safe holding your breath on your way down or on empty lungs right?

-Holding your breath is not a good idea for many reasons, the most important being the risk of an embolism as you already noted. Exhaling and then holding your breath does not change Boyle's Law, just the numbers in the equation. I don't believe that the technique you suggested is safe.

-Another problem with holding your breath is C02 build up. In the extreme cases, C02 build up can lead to hypercapnia - whose signs and symptoms include dyspnea, confusion, drowsiness, rigidity, spasms, loss of consciousness, and headache. To be fair, I don't think we're talking about that much build up, but consider it an fyi.

-The problem with holding your breath while you descend is that when you do finally exhale, your buoyancy will be off and you'll be significantly negative instead of neutral.

-You might check out the photography section, they might have some good tips on how to get closer to the fish.

 

[Boogie711]

Actually not true ... actually what's described is a legitimate breathing technique, although a 3 second pause is a bit excessive.

Skip breathing and pausing between inhale and exhale are very different things.

The first implies that you are actually holding your breath, closing the glotis, for several seconds. This will, in fact, lead to CO2 buildup, as you say.

Yes, certainly true enough. I may have misinterpreted what she was saying. I read "and hold it for about 3 seconds" and assumed a 'traditional' glotis-closed breath hold. You know what they say about assumptions.

The 'glotis-open' breath hold is used all the time to maintain neutral bouyancy on reg exchanges, yes. Certainly, I hope that's what she's doing when she says "holding her breath."

 

[String]

Holding breath is mainly an issue for depth changes (specifically ascents).

Buoyancy control by using lung volume if a different issue all together. I tend to find when trying to stay totally still for a photograph i end up holding my breath to maintain absolute depth.

In theory holding breath at a constant depth shouldnt have any expansion issues (although avoid skip breathing and CO2 retention problems its not recommended you do it a lot).

 

[jonnythan]

Holding your breath, glotis open or closed, for three seconds after every inhale is a bad idea. What effect would closing the glotis have on gas exchange in the lungs??

 

[Ann Marie]

However, pausing for a second or so between inhale and exhale allows a more effective exchange of inhaled air with the CO2 that your lungs want to expel. It just gives the alveoli in your lungs a bit more of a chance to do what they're designed to do. For safety sake you do want to keep your glotis open (like you do with the "aaaahhhh" they teach you in OW).


... Bob (Grateful Diver)

That is exactly what I was attempting to explain. It is very possible that I don't 'pause' for 3 seconds, that just sounded like a good number as I am sitting at my desk and am not actually underwater typing this. The pause that I make is short enough to do what Bob explained above but not long enough to make me feel like I need air. Thanks to all of you that expressed your concerns for my safety. Divers are great!!!!

 

[bober99]

I've noticed a lot of times for bouyancy control and lung volume/breath holding but in my personal experience I don't notice that much of a difference. If I take a full breath in I'm slightly bouyant and if I exhale all of it, I'm slightly negative. Being slightly negative never bothers me since it seems that I don't notice it at all while finning or sculling (used to it since I swim without fins normally). Sure it's nice hovering without moving at all but sculling a bit isn't so bad or energy inefficient. It's not like I shoot up like a balloon or drop like a rock.

 

[miketsp]

..snip..
Buoyancy control by using lung volume if a different issue all together. I tend to find when trying to stay totally still for a photograph i end up holding my breath to maintain absolute depth.
..snip..

I fell into this trap and now avoid it.
Most things we photograph are stationary or slow moving and I was getting into the habit of breath holding to improve the pic.
Then some time ago I was photographing a ray and I was so concentrating on the viewfinder that I automatically held my breath. The ray was absolutely stationary in the viewfinder and I was so concentrated that it took me some time to realise that both my dive watch and computer were beeping like mad. When I finally got the shot I realised that I had had gone up over 10m, fortunately I started at over 25 otherwise the consequences could have been serious. I would have sworn I was stationary.

Now I make a point of maintaining shallow constant breathing while photographing.

 

[H2Andy]

as long as you don't completely close your airway, you're ok.

rather than saying "don't hold your breath" the maxim should be "don't close
your airway"

you can "hold your breath" (i.e. neither inhale nor exhale) and still have your
airway open, which is perfectly safe, as any expanding gas can escape your
lungs freely without doing any damage.

my favorite breathing technique is to slow my breathing down just below normal,
and keeping my airway open, i

inhale
pause
exhale

another possible problem is shallow breaths, where you are getting enough
O2 but not getting rid of enough CO2 (a sure sign of this is a headache
and maybe slight nausea).

thus, i make my actual breaths as normal (and full) as possible. i just slow down the rate a bit and pause after inhaling.

 

[H2Andy]

Holding your breath, glotis open or closed, for three seconds after every inhale is a bad idea. What effect would closing the glotis have on gas exchange in the lungs??

either way, a little more O2 can be absorbed and a little more CO2
can be expelled, but that's not the issue.

the problem in an embolism is sudden expansion of gas which damages
the lungs. if you keep your airway open, the expanding gas has somewhere
to go and is harmless.

actually, three seconds is a bit long, but holding your breath (while keeping
the airway open) for perhaps one or two seconds after inhaling is a good
idea, as it allows for further O2 to be absorbed by your lungs while getting
rid of a bit more CO2.

 

[GOAT]

I have a question related to this. I do not consider my breathing technique to be "holding my breath" but I am a very shallow breather. I can easily get 1 1/2 hours out of an 80 cu ft tank.

however, sometimes i get really sleepy and/or headaches 3 or 4 hours after diving. what gives? am i breathing to slowly/shallow? from the time i take in the breath until the time i exhale the breath is 8 to 10 seconds. But this feels natural to me. If i breath deeper or quicker I tend to get dizzy from too much air.

It sounds like my shallowing breathing may be the problem but it is natural for me. Do i need to practice deeper breaths?