Re: kiai in aikido?
I don't remember the book I read this in, and I am not even quoting or paraphrasing either. This is my opinion based upon what I remember reading.
Aiki is the act of internalizing your ki or energy. It's like you drawing energy in. When you are connecting with uke you are training in aiki. On a grander scale, think of it as you being an antenna for ki. You can receive and transmit. In Aiki mode you are receiving. This makes you aware of what is going on around you. Say someone is walking past, and has ill intention toward you. For some reason this person peaks your attention, as he passes, and you take a few more steps you feel the urge to look behind you, and there he is. This is also Aiki.
Kiai is the opposite of Aiki. You are projecting Ki or energy outward. This has nothing to do with the act of yelling kiai in a technique, well not yet anyway. When you do projection techniques like Kaiten nage, at the end is Kiai. In fact, at the end of techniques is the kiai portion, because you are projecting Ki. Even in an immobilization or pinning technique, your ki is flowing in through the pin and into the ground. Any time you project it is Kiai. Kiai is that scene in the movie when the bombastic captain of the football team walks into a party and everyone in the house seems to know the party just hit an all other level of cool. In non-physical martial aspect, you are upset at the service you have received from a business, you decide to go down to the store to talk to a manager. When you get there, you are determined to get the service and respect you deserve. As you walk up from the parking lot, the people inside already notice you approaching. Some don't make eye contact, others nervously smile and look away or act busy. Those that do speak are polite and call you sir or Mr. That is Kiai.
In Aikido, we tend to focus on AIki. This may be because Kiai is a little easier to grasp and utilize, at least physically. Our goal is to harmonize our balance of Aiki and Kiai to fit our daily living situations. I picture in Yin and Yang Aiki being the black drawing in light and Kiai being white projecting light. As we are walking around we strive for that perfect balance. We are aware of all around us and can at least on a subconscious level feel the energy of others and possibly things. As we recognize through Aiki a strong presence, say ill intent of an attacker (which is him exuding kiai) our Aiki or receptors pick up to verify. As the attack ensues, and we move to enter and blend with the attack our Aiki is rising and we are internalizing and receiving his energy connecting with him. If you go to Kiai at this point, he goes off in whatever direction you happen to be facing along with his flow of energy from the attack. So as you are connected with uke, you are constantly in Aiki and internalizing till you have neutralized the energy from his attack and have taken his center. At the point you are either going to throw or pin uke, is when you start to build up Kiai and project energy to end the technique. The hard part of Aikido is to learn to internalize and not over project.
The act of Kiai or spirit shout, gets its name from projecting. It is standard practice to exhale while projecting and inhale while receiving energy. Don't confuse this receiving the energy from a strike, at which point you want to project. That's why we Kiai when we get hit. We tighten up the muscles where we get hit and project the energy out in a yell. There all kinds of physiological benefits from breathing out when getting hit with a force. Kiai and Aiki here is about energy though.
The rowing exercise, can be done two different ways. You can breath in (Aiki) as you raise your arms, and exhale (Kiai) as you bring them back down towards your sides. You can also reverse the breaths with the exact same motions. Play with that while maintaining Hamni and focusing on Hara. Then try and realize the application of each within techniques.
Like I said, this is my personal understanding of Aiki and Kiai as I interpreted it from reading and studying.It may be way off, and for that apologize if that is so. I may change my view as time goes on and I grow in my Aikido journey. For now, this view seems to help me understand what I am doing physically in Aikido.