I would recommend that you don't force a new breathing rate, or add pauses into your breathing pattern.
Skip breathing (any delays, breath holding, modufications to breathing rate) should be discouraged. Ending the dive with a headache is symptomatic of skip breathing or an unnatural breathing rate.
Discussions on breathing rates, are normally started by new divers trying to increase the length of their dive, normally after comparing their gas consumption with more experienced divers.
The biggest use of gas in new divers are:
* buoyancy adjustments
* to much weight
* not being relaxed (anxious).
* physical fitness
* moving to quickly
As a new diver completes more dives, normally, buoyancy adjustment improves, smaller adjustments and fewer adjustments.
As skills improve, people relax instead of worrying they start to enjoy the dive and their breathing rate drops to a normal "at rest" rate.
Agreed.
The point I'm making is that many divers do NOT breath normally.
However, analyzing breathing at rest such as when laying down reading, etc can help one understand what normal breathing is. Exhaling completely underwater is NOT normal. Exhaling completely, or very nearly completely, is normal on the surface. Pausing 1-2 seconds after exhaling on the surface is normal. Exhaling 1-2 seconds longer than you take to inhale is normal. A full capacity or near full capacity breath is NOT normal. It is a sign of one or more the following exhaustion, oxygen deprivation, CO2 build up that can come from failing to completely exhale. All of which can lead to panic and anxiety, which generally makes bad situations worse.
Breathing is the single most important thing a diver does. It is worth talking studying, talking about, and applying. It is something that can usually be learned slowly through experience, or more quickly through deliberate thought and practice because what is done underwater too often is not normal. It is against sometimes very strong instincts to completely exhale and pause when breathing underwater. Yet that is part of the normal surface breathing pattern.
There are many experienced divers, including instructors and tech divers that wear water heater sized tanks that wear lots of lead that can't stay down as long as divers with aluminum 80s that have mastered the art of breathing NORMALLY underwater.
Have you ever noticed your doctor has to tell you take a deep breath, and there are deep breathing exercises. It is because deep breathing is not normal, but it is something
the cave man in you has you do underwater because it is normal to take a deep breath before putting your head underwater. But, you shouldn't deep breath doing scuba.
All I'm saying is that the is knowable science to apply to the art of breathing that can be learned quickly if done deliberately.
Thankfully, I've heard my brother for years talk about the science and art of breathing for years before I was ever talked into doing scuba myself.
For me completely exhaling underwater wasn't a problem. I have however had to give a little thought to not taking all the air the regulator will give to me. Yet, paying attention to breathing has allowed me to start out on my OW check out averaging a little below .7cuft/min and go below .4cuft/min while doing safety performance task in the pool. My highest consumption was trying swim to keep up with my brother while he reef crawled. My consumption shot up to 1.0cuft/min, which is 40% more than average consumption and over 200% of lowest consumption. Kicking legs need a lot more air than crawling arms, and the crawling arms are more effective in a stiff current. Two lessons good lessons on one dive.