butterfly and underwater swimming

Question
Hi Coach:

Thanks a lot for your advice. I am a little bit confused about your technique and may I ask a question about it:

You advised me to exhale in a controlled way when I compete my 25. and you said in that way I could keep my muscles oxygenated better. But I think if you take a big breath before you go and before you even use any, you start to exhale some of them out. Isn't that a waste? under this way of thinking, I used to take as much air in as I could and I try to hold them so my body could gradually use them. Is there something wrong with my thinking?

thanks again for your help and I really appreciate it.

Heng, yan

Answer
As soon as you start holding your breath, you start building lactic acid.  If you exhale slowly after a big breath your body doesn't build up carbon dioxide or lactic acid as quickly.  Also the more relaxed you are when swimming under water the easier it will be.
George