I am not home, so I can't look this up, but do a check on google for yoga breathing.

I have used yoga breathing in the past, and found that it has tremendous advantages. As you become more efficient at deeper breathing, you'll find that you'll be able to bring in more oxygen and train more efficiently with the increase in oxygen. Not to mention it keeps you calmed and grounded at times when your training becomes more intense.

I'll check for some of the reading I have when I get home and post some tapes and books I've read on deep breathing.