I have discussed Jion in the past.
For 17 years our program was most fortunate to have Paul Harper Md FACS training with us. As a Surgeon he made many contributions to our studies together. But in time he had to follow his own path.
His many contributions are still with us.
I recently discovered yet another Doctor who is sharing his medical knowledge helping us understand more about karate and modern medical knowledge.
I offer the following vides RH Gutierrez has made, as worthy studies. We all might gain more from watching them.
The basic motion is found in Chinto kata, but the potential is one not ofter considered, the inside of the stepping strike, not the extended strike on the end. I first learned this drill as a basic drill in another system, but after decades of practice, came to realize it was also in Chinto kata. It is also a portion of the Tai Chi Da Lu drill.
The left hand deflects their arm up, then down as it snakes over and rotates the palm pressing into their arm. The right forearm which has been rotated also palm up parallelling the left arm, presses into their left arm triceps. The two arms in unison use the left torso rotation to bend the attacker forward. As their center of gravith has shifted to their biceps, this caused them to move forward and down. A takedown or a projection.
2.This motion came to me from training with Sherman Harrill, When I tried it for the first time on Young Lee, who had no idea of its existence, he was dropped to the floor. Worked the first time, and every time since.
A. Exterior line of Defense - Against a right stepping right strike. You step forward with your left, and throw a right inward horizontal elbow
A major influence as spreading information on Chim-Na is Dr, Yang Jwing Ming. With a background in several Chinese systems, and also with the logical mind that goes with a PhD in Engineering, by the 1980s he saw the relevance on sharing that for other martial artists through clinics, programs, books and video tapes.
Being most logical his books detailed many of the components of Chin-Na training. They accompany the many fine video’s he created.
I had attended a clinic and workshop he gave on various arts. But Maureen Smith, my wife, took a 9 month course he offered on Chin-Na back in 1989. I was her practice partner, It was a painful time.
A great many of his videos may be found on YouTube, This is an example:
While not exactly a practice of original karate, it does offer logical movements that can combine with karate.