Okinawan "Iron Body" training: this is a brief outline of the impact conditioning (called "Dako" or the "Daruma Excercise") I use as part of my training. It focuses mainly on the throat and neck, This is not instructional. Do not attempt this on your own, it is potentially harmful and is inherently dangerous. This training is most benificial when used within a broader training regime (including basic kokyu-ho, Sanchin training and Naihanchi training. This kata training works visualization, breathwork, focused intention, and physical posture, as well as either "dynamic tension" or "extending tension" (or some combination of both). All this training can be lumped together under the heading "Okinawan kiko". Kiko training also involves a host of various ancilary methods. Done in isolation, impact conditioning is not nearly as effective as when part of a complete kiko regimen.
I use the terms "beginner" or "somebody just starting" to refer to each stage... In other words when I say "I wouldn't recommend a beginner use two rubber bands on a restricted steel hitter" the "beginner" in that sentence is somebody new to the stage beyond training with a loose steel hitter. In that case it is talking about somebody who has spent a couple years doing this training and who progressed through a loose bamboo hitter, restricted bamboo hitter, and then the loose steel hitter... So "beginner" always means "new to the next stage".
Regarding knee training:
I use this exercise to strengthen the fascia, muscles, tendons, ligaments, and (to a lesser extent) bones of the knee joint. You cannot use iron shot or similar material when conditioning the joints. You must use a material that is softer and less dense . So I poured a 5 pound can of mung beans into a canvas bag. I then added what was left from another can. I am guessing the total is about 5.5 or 6 pounds of mung beans.
The force should be sufficient to turn the whole area bright red but not so excessive as to cause noticeable bruising. Everybody is different, so there is no single level of intensity for everybody. This is done 3x per day. It only takes about 2 minutes to do both knees. By Okinawan standards this is actually pretty light training.
Inhale the visualized breath/ki down the center of your body to the tanden.
Exhale the visualized breath/ki from the tanden down the legs to the knees.
Imagine (and cultivate the resolved intent) that the breath/ki strengthens and reinforces the knee and making it 10x stronger.
It is extremely important to thoroughly massage the entire knee area after training. This exercise can potentially cause stiffening in the joint if you don't do a little "cool down" stretching after the massage.
Again: DON'T TRY THIS AT HOME.
It was very much filmed "off the cuff". I stammer and stop, then ramble and repeat myself... I am sure I am not covering anything you haven't been exposed to in one form or another, but here it is all the same.