Re: The "Jo Trick" and Similar Exercises
I have seen some pictures of the jo exercise and a brief clip of it in one video but I don't remember which one offhand so I don't have any firsthand experience with it.
However, I do have experience with the concept of the unbendable arm ki exercise which is similar. When we train with this I place my arm with my forearm extended just over the shoulder of my partner with my elbow pointing to the ground. My partner places his hands over the bend in my elbow and attempts to bend the arm while I am focusing on extending my ki through the arm to keep it straight. The arm is slightly bent at the elbow, not locking the joint out, and the arm stays relaxed so you can even wiggle the fingers while your partner is attempting this.
I can do this successfully and can attest that at 5'10", 185 lbs I can exert a lot of force and not bend someone elses arm who is doing this while I am trying to force their arm to bend as well.