In answer to a few of the questions raised:

What is forced?
I am forcing the cadence, not the work done. It's not clear to me from the tandem studies what is forced: using the gears, a strong cyclist at the front can increase the cadence, but can't force the person at the back to do any more useful work.

Forced exercise or forced movement
It's unclear to me the extent to which the arm is passive in my set-up. It seems to me that it soon keeps pace with the movement. Some work is done, but at a much lower rate than appears to be the case in the tandem tests.

Forced movement would be a reasonable description but for the fact that some people may take that to mean things like stretching. I've not looked at that, not least because it is potentially dangerous.

I've now got 4 weeks of data. The measure of performance is the number of taps in a minute. (Remember making a tap to the left and then to the right counts as 2. So to get an equivalent cadence or rpm figure you need to divide by 2.) The protocol described above was followed (except for changes already described, and in the last two weeks the drill's rpm was set to approximately 90). The daily sequence of results were:

88 74 81 88 88 79 87 87 90 108 99 101 101 99 112 106 115 111 104 110 109 106 114 103 115 114 100 115

The weekly averages are 84, 99, 110 and 110.

Subjective assessment: right (worst affected arm) less stiff, left arm more tremor; overall up and down as usual, on average about the same.

It is too early to say whether there is any causality.

The usefulness of the results is affected by:
- the placebo effect;
- the extent to which the increase in the performance metric is due to learning to pass the test itself, rather than underlying ability. I should have allowed at least a week doing the test without FE to get a better baseline.

John