This post was previously published on March 23rd under the title Crutches. I am republishing it and adding a short comment because I believe that the subject is very important.
If you have a sprained ankle or broken leg, you will need crutches until you recover.
In Kishaba Juku, we are sometimes asked about our use of a "double hip."
In order to develop power using your whole body, it is necessary to connect your upper and lower body through your core and koshi. Hip motion is an important aspect of generating and directing power.
When a student is stiff and not used to a rotary use of the hip (koshi), we will try all sorts of exercises to get him to loosen up and move his hips. One such excercise is using a double hip movement.
Of course, such a movement would not be useful in practical circumstances -- it is too slow. The use of a double hip motion is just an execrcise, or crutch, until the student catches on. But if a student only learns to that level, he might think that it is used at all levels.
Once you are healthy, you no longer need crutches (for hip movement or otherwise).
The use of the koshi is very much like the mechanics of a whip. If you get a damp towel, twist it, and practice snapping it, you will learn a lot about koshi dynamics. When you snap the towel just right there is no double motion either.
We do not use a double hip or double pump. That is just an execise until the student learns to move more naturally. But when the student learns that exercise and does not progress further, he might think that the double hip is part of our basic technique. Like crutches or training wheels, double hip movements can be set aside when they are no longer needed.
Charles C. Goodin