Saito sensei gave a bit of instruction on breathing. When attacking you should always be breathing out, inhaling is a suki (opening).
He said that sometimes when you watch kodansha (high rank holder) they are waiting and try to make a chance. They are waiting to see who breathes in first and attack then. We did a practice where we tried to extend one breath as long as possible and 'win' against the aite (opponent) by attacking when the inhaled.
Kendo-Guide.Com: Thanks for sharing. There is an article on that as well in Breathing in kendo.
