I e-asked the esteemed Tom Bisio IF it was not top-secret would volume 7 of his Nei Gong series will have any exercises for the bottoms of the feet. Tom Bisio said no volume 7 planned and no exercises for ankles or feet. However, he encouraged me to publish.
In terms of tai chi bar, I am probably a poor test subject. I get irregular or inconsistent results – partly rolling and partly sliding of the bar, so I figured that was me doing something wrong with the two pressures:
1. there’s the vertical (downward) vector of some weight on the foot and
2. the more or less horizontal pressure trying to move parallel to the ground.
There are, as readers have likely guessed, two versions of the stationary bar. In one the bar can spin parallel to the ground somewhat similar to toilet paper. In the other version the bar does not move at all. No one (not one person) thinks either of these is satisfactory. The primary complaints have been (1) not enough pressure on the heel; (2) skips over the section between about the middle of the foot to just past the cuneiform bones (3) misses the distal metatarsals.
I have asked about the so-called porcupine balls. To needle Charles Tauber, so as to speak, I said I had nothing against the famed Canadian super-rodent (Erethizon dorsatum – below right), but the balls more closely resemble a hedgehog (below left). In either case very few people think the gizmos do any good as they are too flexible and too mobile so there is nothing deeper than tickling the skin. Charles was none too enthused about the idea of rolling the bar guided by grooves. So I suppose we will look into rolling a smooth bar (like a bang) inside a box.