Lowered my SAC, got a free headache

[Matt S.]

On a dive this weekend I spent a lot of effort on improving my air hogging ways. I did succeed in lowering my SAC from the usual 0.8-0.9 to 0.6. I also found that I had a headache at the end of the dive, presumably from CO2.

My buddy, an experienced local that I was diving with for the first time, suggested taking a normal breath but then exhaling slowly--not making inhale and exhale slow. Any other tips?

 

[tc]

Relax.

 

[Warren_L]

On a dive this weekend I spent a lot of effort on improving my air hogging ways. I did succeed in lowering my SAC from the usual 0.8-0.9 to 0.6. I also found that I had a headache at the end of the dive, presumably from CO2.

My buddy, an experienced local that I was diving with for the first time, suggested taking a normal breath but then exhaling slowly--not making inhale and exhale slow. Any other tips?

If you're getting a headache from breathing too slowly, that should tell you something - namely you need to be breathing as fast and as fully as you normally would so that your body can clear the CO2. Purposely slowing down your breathing like that would seem a recipe for disaster.

Examine the possible causes for why your SAC is higher than you want. TC mentions one possible factor - you're not as relaxed as you could be, causing elevated breathing rate. Slow down and calm down would be a good start.

Also look at things like your weighting and trim. If you're carrying around more weight than you really need then you might be fighting to maintain your buoyancy by yo-yoing, which of courses uses more air from your tank as you go up and down (and presumably you're calculating SAC from your tank pressures after the dive). Also, if you're not horizontal in the water then you're going to be working harder than you need to to move through the water. All this adds up to more air consumption.

Purposely trying to slow down your breathing in and of itself I would tend to avoid doing. The slowing down your breathing should be a result of some actions, not an action itself.

 

[Jeff Toorish]

Of course, you may just need a lot of air, in which case, getting bigger tanks would help.

Jeff

 

[Peter_C]

I found the solution to the same problem. First I tried breathing as hard as I wanted to (I have HP100's and most of my buddies dive HP 80's)...didn't work! Headache ouch! Ibuprofen was the only way I could dive without a head crushed in vice feeling happening. Even with Ibuprofen, it was only bearable. My desire to dive continued, but I would often sit out the second or even third dive because of a headaches...and the cold here brrrr (Drysuit solved that issue, or at least made it tolerable)

So onto the solution already NITROX!!!!! Once I started diving Nitrox, I lowered my sac rate substantially, and no longer have headache problems. We are diving the coldest water of our season right now, due to upwellings, and I feel fine We have done multiple dives of 80 minutes with no issues at all. I have not done a trillion dives on Nitrox yet, but strongly feel it was a factor in lowering my sac and more importantly ridding me of painful headaches.

My weighting is set just about right. Last time out, I added 4 lbs to gain some loft in my drysuit. I am very relaxed underwater, and like to dive pretty slow. Got complimented on the speed I chose as the dive leader last time out. I had tried many different things to reduce headaches. So far Nitrox is the winner.

 

[Willie]

Early on a more experienced diver told me he takes as slow and deep a breath as he can and then exhales slowly. I adopted that practice more or less. Never was all that concious about it.

After about 100 dives or so I had gotten quite a bit more relaxed in the water and much more consistent at buoancy and trim. Those two factors (buoancy and trim) have had the biggest effect on my SAC so far.

I begin to pay more attention to my breathing and I did notice that on the surface I rarely took very deep breaths, only when really exerting myself. I began to concentrate on taking 'normal' breaths when underwater except in periods of exertion. I defined normal as that which was normal for me on the surface. I have found that my SAC improved somewhat again. I also have much finer control of my buoancy than I did before.

Willie

 

[CameronMartz]

CO2 headaches are brutal, but they are no badge of honor for a diver. This is a sign that you are artifically slowing your breathing below your natural metabolic requirements, and the CO2 building in your bloodstream is changing its pH. It can lead to increased narcosis, it makes you more susceptible to CNS oxygen toxicity (a seizure under water is usually lethal), and it can cause a loss of consciousness all on its own (also usually lethal).

It's not so bad to want to improve the efficiency of your breath cycle, but that has only a very small effect on gas consumption. Before worrying about your breath cycle, you need to correct any wasted effort. I have an article with the most common suggestions at http://www.divefitness.com/html/articles.html, under "Breathing Heavy: How to reduce your gas consumption."

There are many good reasons to switch to Nitrox, but it will do nothing for CO2 headaches. It doesn't matter how high a partial pressure of O2 you're breathing- you will still be producing the same amount of CO2 at a given metabolic level, and it is too much CO2, not a lack of O2, that causes these headaches.

Cameron

 

[rawls]

Matt,

I am an air hog and always will be an air hog...I am 6'4" and just have a really large lung capacity. It is simply the way I am made. As far as any other suggestions...I had to ultimately practice acceptance

 

[spectrum]

You need to go deep on the exhale in order to vent the CO2 fully.

More air in by itself is not the answer. In the hyperbaric state of the diver you have more oxygen than you know what to do with. If your modified breathing style had you breathing off the top of your lungs then stale air was accumulating in your lungs and tainting you blood with carbon dioxide.

Normal inhale and slow exhale is sort of what has evolved for me. By taking the air in at an average rate you will also have a more consistent state of buoyancy. If you do inhale and exhale slowly you can picture your buoyancy as a long lazy sine wave and you will tend to porpoise.

With the slow exhale you will be ready to inhale just as your buoyancy begins to react to your displacement change and as you inhale you will counteract the fall that is just beginning.

Breathe deep and pay attention to what's happening. For me it was all about being comfortable and then nice SACs just started to happen.

Pete

 

[fppf]

Don't worry about it to much.
Get some more dives in and it will come down naturally.
If it don't, that is why they make bigger tanks.