Originally posted by animian2002
I thought the key point is we are not supposed to hold our breath underwater and in order not to do so aren't we supposed to slowly exhale..
Ok... the holding your breath thing. The reason you are taught to constantly breath is because people naturally lock off their airway to hold their breath. This is a problem on two sides of the coin. First, when your holding your breath, you usually have your lungs full. When your lungs are full and your bouyancy is right, you will be positively bouyant at that point. Now if your holding your breath, and your positively bouyant, your going to rise some. As you rise, the air in your lungs expand, and since you have your airway locked, it's going to end up damaging your lungs. The deeper you are, the farther you can rise without damage, and likewise the shallower you are, the more dangerous it is [a 3 foot rise at 15 fsw with full lungs is enough to rupture your lungs].
So as long as your breathing, your lungs aren't locked off, and if you ascend while breathing, the expanded air just goes out. Much like what will happen if you take a deep breath, breathe out slowly, and then push on your chest... you will just breathe out faster.
Now to go a little beyond, but something to think about, there is a big difference between 'holding your breath' and 'stopping breathing'. I'm not recommending you do this by any means, but one can 'stop breathing' at which point your airway is still open so expanding air can escape. Try it while you sit there. Breathe in deep and lock your airway. Push on your chest. No air comes out. Now breathe in deeply but just stop breathing and see if you can keep from locking your air. if your breath is too deep, you will exhale some anyway, once the natural chest compression has completed, push on your chest with your hands... if your airway isn't locked, you'll force air out of your lungs.
Once you start getting comfortable in the water, and you understand you can breathe at the bottom of your lungs to descend, full breaths once neutral, and high breaths to rise some to get over stuff, people sometimes start what is called 'skip breathing' to conserve air.
skip breathing is holding your breath between breaths, in the middle of the breath. I'm not going to get into _why_ this is bad, but trust me... you don't want to do it [it gets into CO2 build-up and all of that]. When it comes time to work on your air consumption, just slow down your breathing, but constantly breath. When I'm really relaxed I find my breath cycle is around 25-30 seconds.
The moral of the story, think deep slow breaths, and deep is really key for getting the weight off...