Alanfraserpiano
A few days has stretched to over a year... Does this mean you gave up, or that you have had such great results that you haven't had time to post anything, you are too busy enjoying your newly empowered thumbs?
I myself continue to be fascinated by their unique role in piano technique. And I continue to find new solutions. Look at films of Gyorgy Cziffra especially, but Rubinstein and others as well - their thumbs seem to stick out from the hand a lot of the time, pointing to the inside, rather than hanging down, relaxed.
I have been experimenting with this, sticking it down and away from the hand more on purpose instead of merely leaving it neutral. Instead of only inhibiting pianistic co-dependence, I go one step further and consciously do the opposite.
This creates a whole new hand structure, where the 'strut' aspect of thumb and fifth finger is vastly enhanced. The peak of the double arch, the second metacarpal-phalangeal joint, so now supported functionally by the other parts of the hand. Actively pushing the thumb away from the hand down into the key, or in the direction of the key when it is not playing, does wonderful things for the potency of the whole hand structure.
Does this ring any bells?
AFF