Re: Kesagiri suburi, etc.
This is currently an enthusiasm of mine, because I keep finding connections between the sword work and taijutsu. The kesagiri exercise is particularly deep because it involves horizontal movement from the hara, a change of hanmi, and the sword stroke, all integrated. It's not about crossing the centerline, exactly--it's about distributing power horizontally using the hara.
The exercise I'm talking about here is a basic Kashima exercise: diagonal strike from left to right while stepping into a left hanmi; reverse, sword circles around into a diagonal strike from right to left while stepping into a right hanmi. The "step" is forward on one foot, back on the other so you don't actually move. Repeat forever.
Here's a short list of things I'm working on right now:
* Movement initiated by moving the hara, independently of and in advance of the hips and shoulders.
* Raising the sword without using arm strength.
* Bringing the sword down without using arm strength.
* Relaxed shoulders throughout the movement.
* Full ki extension from the hara, through the arms, out the sword, across the gym.
* No slack anywhere in the movement. No loss of connection between the hara and the sword.
* Hanmi low and relaxed. Knees open throughout the movement, including the moment in the changeover when the feet are together. Head at the same level throughout the movement. Weight between the feet at all times.
* Knees and kua relaxed. Momentum of the sword taken around the body and absorbed through the forward knee.
* Ki extension forward balanced by ki extension backwards. Body completely centered and on balance throughout the movement.
* Awareness and intent focused forward throughout the movement. Stroke ends ready for the next stroke.
Much of this could be practiced with tandoku undo, but the sword makes it more obvious if you're doing it badly. After 1000 suburi with a heavy Kashima-style bokken, you'll know if you're using arm strength to raise it. If you check your posture at the end of each stroke, you'll know if you're on balance. The weight of the sword gives you something to pull around with your hara--if you're just moving your arm the difference between moving it with hara and not is much more subtle. Because kesagiri is a diagonal movement it's easier to free hara from hips and rib cage, whereas it's easy to practice tandoku undo treating the whole trunk as a unit.