This was awesome read. I have never ever done a breathing exercise or knew anything about the arousal etc. But what I used to do was the following:
1. Prepare myself with all the anxiety and sort of work it up to a level I can sustain. I just did it, no measures or calculations as such.
2. Just before the attempt I take about 30 seconds of very relaxed deep breathing (just focusing on getting lots of air in and out, no such patterns like you have mentioned in the article (which I will start using from now). From a very aroused state, I tend to get some sort of stable arousal or sustained I would say.
3. When I approach the bar, I am mostly calm and body pretty relaxed ( being over hyped never worked for me, I used get burnt out in the aggression) but it all comes back i.e. the aggression etc just when I go under the bar or I set up for deadlifts.
4. And pop, the weight moves (most of the time it does :))
But now, I will incorporate some structured breathing exercises, reason being, even with the above stated approach, there were times I am was out of breath and too much of quick/ deep breathing was making me giddy.