Re: Posture in Iwama Aikido
Scott - you're welcome. I'm glad I could be of help.
Phi - to answer your question: first of all, the forward hip is engaged to put more power in to the strike.
Furthermore, the weapons forms in Aiki Ken and Aiki Jo as taught in Iwama are based on the concept of "riai". Riai (ri meaning principle, and ai meaning harmony or fitting together) is the term that refers to the concept that O-Sensei emphasized in his teaching in Iwama: that the weapons forms and the tai jutsu forms fit together; the movements and the postures and positions are all the same. Saito Sensei always referred to O-Sensei saying that when using the ken or jo you should think of doing tai jutsu, and vice versa. So when we throw in tai jutsu, for instance in Irimi Nage, we engage the front hip before the downward throwing movement of the arcing arm. This creates a very strong and stable hip position and gives great power for the throw. It's the same movement in the lower body as the (Iwama) basic shomen uchi suburi. This is one of the reasons why all our basic suburi strikes, both with jo as well as ken, go down to the horizontal position, even though they are called "men uchi." Saito Sensei always said "Tsuyoi koshi wo tsukuru tame ni..." "To create strong hips."
My understanding is that if you are cutting with a live blade you can probably cut through most anything with ease, as long as you have a reasonably stable form. But the bokken should also be considered a weapon in itself, and in order to create a maximum power output in our strikes we put the hip into the strikes (as well as our tsuki and other basic attacks). If you try practicing tanren uchi it is very evident that there is a big difference in your strikes when you fully engage the front hip from when you stand in a position with your hips forward (horizontal).
Please understand that this is the way we were taught in Iwama by Saito Sensei, with his references to how he learned it from O-Sensei. There are of course many other ways of doing these forms that all have their own merits - of equal value. There is no single right way of doing things. I'm just trying my best to train the way I was taught, to understand it and to transmit it to those who wish to learn it the way I did.