Doron Navon from Israel started training with Hatsumi Sensei in the late 60's long before the "ninja-boom". When he came home from Japan 1974 he had so many injuries that he could hardly move for a long time. He was introduced to Dr. Moshe Feldenkrais who founded the Feldenkrais Method, and learned this method directly from him.
Doron says that the Feldenkrais method is a shortcut to the godan test. This has been confirmed by both Hatsumi Sensei and many other who have studied Taijutsu and Feldenkrais.