Lowered my SAC, got a free headache

[Matt S.]

I don't know how much more relaxed I could have been--it was a great dive. My best yet, in terms of technique. But there are probably a lot of wasteful motions that I am making and unaware of. I should get someome to film me.

Those of you who suggested bigger tanks--heck yeah, they are the next item on the shopping list. I'm thinking something around 120 for me and 100 for my wife. (We dive dry in cold water.)

Thanks for the comments everyone.

 

[Nemrod]

You cannot just decide one day to breath and consume less O2.

1) work on water skills, balance, trim, weight,comfort and confidence
2) Jet Fins or other powerfull fin
3) put your arms down to the side or cross them and leave them there
4) a good easy breathing regulator
5) reduce drag and eliminate clutter, complexity and un-needed items
6) get your trim correct so you can sit horozontal without madly finning all the time (wing/BP helps here)
7) Inhale deeply and then exhale slowly over a longer period
8) FITNESS---get in shape, loose some weight
N

 

[TSandM]

I don't think fitness is playing a big role here, and Matt's not overweight. He's just new. And like most new divers, he's wishing he used less gas so he could stay down there longer!

Matt, if you want to get together some time this month, I'll bring my little camera and do some video for you.

 

[Peter_C]

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.Cameron

I am susceptible to migraines thanks to genetics. I get headaches above the water too, but not nearly as bad as underwater. As I said above, I tried taking big, deep breathes, and did not find it helped. Even tried to almost hyperventilate, to see if that would change anything. Nope.

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

I still have no idea what causes my headaches, but will swear up and down, Nitrox has helped ME with headaches. It can never hurt to get certified and give it a try!

Skip breathing was never mentioned above, or at least I did not see it. That is a common problem with many divers, and by trying to slow your breathing down you may inadvertently be doing it. Try to keep the air constantly going in and out, without ever holding your breath, not even for a second.

I agree with much of what was posted above, to simply relax. In fact forget about breathing and just dive. Enjoy the surrounding's, and when you are low on air surface. In other words, if you spend time enjoying yourself, it will help you relax. Some of the bigger guys I dive with do use LP95's or larger, including a couple of HP 120's.

 

[Nemrod]

quote: "I don't think fitness is playing a big role here,"

My comments were general and not specific to Matt who I don't know. He may be super fit in which case he does not need to worry over item 8 in my list, one down and seven to go.

Here is another item, do some neck exercises to limber and strengthen neck and shoulders and improve flexibilty. I think yiou could be tensing your neck muscles to hold your head up--arch the back instead. This could cause or induce a headache.

Skip breathing is not the same as taking a full inhalation and then slowly exhaling. Shallow breathing wastes oxygen content, a full breath followed by a slower/longer exhale allows the oxygen in each breath to be more fully utilized. This is not to slow down your breathing to the point of breath holding or skip breathing or CO2 buildup--no. In fact it shoud reduce CO2.

When I first took scuba instruction I was told to inhale fully and then exhale slowly and completely. Now they tell divers to breath normally. Well, if your normal breathing is a shallow pant then that is not what you want to do and will waste air.

Good luck.

N

 

[ClayJar]

I still have no idea what causes my headaches, but will swear up and down, Nitrox has helped ME with headaches.

...as long as it's not a symptom of PFO. I'm glad I don't get migraines, as I'd probably be a bit scared to dive before being checked out. (I'm not a hypochondriac, but a story or two of late were at least a little frightening to my conservative nature.)

 

[Charlie99]

My anectdotal observation on fitness: My overall fitness level doesn't seem to have any material effect on SAC of a normal dive. Where it DOES have a big effect is one a dive where I'm working hard against a current, or doing a long unusually fast transit.
When fit, my SAC doesn't increase as fast in response to heavy workload as it does when out of shape.

This shouldn't be all that surprising since I know that if out of shape, when using an incline treadmill I'll be panting, out of breath, and breathing rapidly at the same workload where I'm comfortable with normal breathing when I'm in good aerobic shape.

 

[dumpsterDiver]

I have been diving for dozens of years and my SAC rate is going up, not down. I'm bigger, fatter and my cardiovascular fitness is continuing to degrade as I age. My SAC is around 0.8 and I don't think this is something to be ashamed of, or something that I should conciously try to reduce. I carry enough gas to do the dives I want.

People constantly talk about their SAC rates, but we often don't hear about their size or weight. I think that for someone to determine if you are really breathing too much air, we really need to know your size. A man who weighs well over 200 lbs and is carrying a lot of muscle (regardless of his fitness level or underwater activity level) is going to burn more air than most any 105 lb women doing a similar activity. Isn't this what we hear from the fitness nuts: "If you increase your muscle mass, your basal metabolism will increase and you will be able to eat more and you will even burn more calories in your sleep!!!"

Trying to relax, maintaining good bouyancy and breathing patterns and moving through the water in an efficient and streamlined manner is a worthwhile goal, as is trying to improve your cardiovascular fitness, but trying to simply lower your SAC during a dive by breathing less than YOU need, makes little sense to me.

I have suffered from dive headaches and note that they are often correlated with cold water, high exertion level and very often occur if I have not dove in a while. I often end up taking an ibuprofen after 2-3 dives.

 

[Matt S.]

And like most new divers, he's wishing he used less gas so he could stay down there longer!

You said it.

Matt, if you want to get together some time this month, I'll bring my little camera and do some video for you.

Thanks... My little camera does video too, but if I can't get Etien to shoot me I'll let you know.

You cannot just decide one day to breath and consume less O2.

I can't change my metabolic needs overnight, but if my natural breathing pattern is wasteful of gas volume I can work on that, right? The fact that I did get a headache means I tried too hard, obviously. (Though maybe I'd rather have a headache than a SAC of 1.1 like I did a couple of weeks ago!)

Regardless, bigger tanks are part of the solution. I really wish I could rent something bigger than 80 in the meantime.

 

[CameronMartz]

Isn't this what we hear from the fitness nuts: "If you increase your muscle mass, your basal metabolism will increase and you will be able to eat more and you will even burn more calories in your sleep!!!"

From the uninformed, but they are unfortunately wrong (some of the worst fitness myths spew forth from fitness "professionals" every day). Daily energy expenditure is most strongly correlated to total body mass, and not so much to body composition, meaning that gaining a pound of fat requires similar caloric expenditure to carry around as an extra pound of muscle.

Think about losing 30 pounds. Now, think about putting 30 pounds in a backpack and carrying that around with you all day. That's hard work that demands a lot of calories (and O2).

Now think about adding 10 pounds of muscle and only carrying 20 pounds in the backpack. Total body mass is the same- do you now burn more or fewer calories each day? Gaining muscle makes ordinary movements easier, and it seems that the overall effect washes out over the course of a day. Depending on the type of conditioning done, muscle can also *reduce* caloric expenditure at submaximal levels of activity.

But, this still supports your point that higher body mass means higher basal metabolism, all else equal. Keep in mind, though, that most divers concerned with SAC are probably far from their basal O2 consumption regardless of how big they are. There are many large, experienced divers with low SACs.

To this point, a bigger tank might allow longer bottom times, but it might be missing the issue. Efficient diving is more than just about bottom times- the more you work at depth, the faster you are loading inert gas. All of the hints about dive skills that have been raised here can lead to reduced gas loading, but a bigger tank does not.

Cameron