Re: Training "Aiki" with Dan Harden
Hi Tim - I don't have a clue. I know several people who lived at the Yoshinkan and none of them recall any solo training by Shioda, except the "tai-sabaki" exercises that everyone did.
Here's a puzzle though: he is also not known to have done the Misogi-kai exercises that Ueshiba made so important in his later years.
AND - furthermore, I've been told by a senior Kodokai instructor that the Kodokai, unlike Sagawa's branch of Daito-ryu, does not particularly have solo training either. This individual said that he personally developed some solo training to assist himself, but it was not part of their particular system. (Don't shoot the messenger - just what I was told - maybe, some will say, he was being dishonest to me, an outsider, and keeping a secret).
Regarding the "impossibility" of developing internal power w/o solo training - Kuroda Tetsuzan's Komagawa Kaishin-ryu has a number of solo and dual training exercises. He told me, however, that he made these exercises up. In the old days, he said, all they had was two person kata. But people then were willing to practice the kata 'til they sweated blood and furthermore, they had the willingness and the ability to allow the kata to "pervasively" influence them - it was all they thought of, felt and experienced. After awhile, drinking a cup of water was Komagawa Kaishin-ryu. Kuroda said that because modern people don't have the time or the willingness to give "everything" up, he needed to develop such training exercises as a short-cut.
Similarly Chen Village t'ai chi reportedly only practiced the form(s) at one point, but the present generation developed a set of "silk reeling exercises" to facilitate development.
I'm on a good respectful basis with Inoue sensei of Yoshinkan - when I'm next in Japan, I'll ask him directly about this.