Why shouldn't we hold our breath underwater?

I realize this is one of the cardinal rules for scuba diving. Never Hold your breath underwater.

I know that this can cause injuries when surfacing.

But what if we are stationary, and trying to take a photo shot? Or posing for a picture? Or trying to navigate through a tight rock or ship opening? What exactly happens when we hold our breath in those instances?

The short answer: nothing.

A short period of breath hold for the examples you mentioned are acceptable once you've refined your buoyancy control. Just don't do it repeatedly.

There's a long answer, too, and a search for "CO2 retention" and "lung over expansion" should satisfy inquiring minds.

"Never hold your breath" is actually a short-cut phrase to tell new students "always leave your airway open." It's useful as it's binary and very easy to understand. Of course it's entirely possible to have an open airway without inspiration/expiration, and divers pretty quickly understand that often means holding an inspiration a beat or two longer than normal to rise a foot or two, or pausing on an exhale for a moment to get a clear photo shot, etc.

I think that they drum that lesson home of simply not holding your breath underwater because new divers are likely to have poor buoyancy control. If they told you not to hold your breath and ascend (the actual cause of lung barotrauma), you might figure it was OK to hold your breath and then injure yourself as you ascended without realizing it.

You can't injure your lungs by holding your breath and staying at a constant depth, although this can put you at risk for CO2 retention, hypercarbia and the neurological symptoms that can come with that. That's why "skip breathing" is discouraged.

However, I routinely hold my breath for photography, especially with shy macro subjects.

There's "Never hold your breath" written in stone. Then there's ".... and go up" written in invisible ink.

There's a difference between "holding your breath and closing the valve" and "stopping breathing for a minute with the valve open".

The "valve" here being the throat.


All the best, James

I routinely hold my breath when hovering above a flounder, then descending 2-3 feet to poke spear it for supper. Descending is OK also, as long as you don't start with near empty lungs then descend a long way (lung squeeze possible--I've read this could happen if free divers do this with near empty lungs).

Probably another reason beginning divers are told never to hold your breath is that maybe 20%(?) of them have airway control problems --ei. can't clear mask because exhaling through mouth at same time as nose, or having problems with the no mask swim with nose exposed to water--not being able to close off the passage leading to the nose thus probably not able to keep it open unless exhaling through the nose, or mouth--control of the glottis. It just makes it simpler and pretty much 100% safe if they just don't hold their breath. Same reasoning as exhaling and going "Ah" when doing a CESA, as opposed to just ascending with airway open. On a related note, I have read that even when exhaling and "Ahing" doing a CESA it is still possible for lung overexpansion if you ascend too fast and some air gets trapped in an odd corner of the lung. Best to follow the rules-- better safe than sorry.

There are some rules that are better simplified in the early stages of learning.

Sort of like "Always dive with a buddy".

You've got a newbie OW student to teach. Might become a vacation diver who dives on a trip every 2 or 3 years, likely with no refresher course. You can train extensively to the degree of mindfulness of personal functioning and depth positioning, coupled with the buoyancy control and multi-tasking/task-loading tolerance to do the prior things while enjoying the scenery, keeping up with a buddy, finning or hovering, mask clearing & venting or inflating a BCD...

Of you can teach him 'Never hold your breath is the number one rule of scuba diving.'

Richard.

sipadiver:

I realize this is one of the cardinal rules for scuba diving. Never Hold your breath underwater.

I know that this can cause injuries when surfacing.

But what if we are stationary, and trying to take a photo shot? Or posing for a picture? Or trying to navigate through a tight rock or ship opening? What exactly happens when we hold our breath in those instances?

Click to expand...

Someone else covered it off well.When training someone at anything MOST people respond best to clearcut black and white.
so muddying the waters with"ohh its ok if you are stationary and its only....." is confusing.
A lot of folk who are learning or just don't dive much need simple clearcut rules.-especially in a task loaded situation.