Rotation in Scale Playing

Richard Beauchamp, April 2004
For some time I have been reluctant to put these pages on the web because I know how  easy it is to misinterpret instructions about rotation in piano technique. However, I now realise that those who visit these pages are almost always wise and well balanced people  in the first place and therefore unlikely to take information too literally or any of my advice  to ridiculous extremes — if at all.
Rotation movements are often (but not always) so small as to be almost invisible. Indeed they are often invisible and then are really only supporting movements made by the muscles that pronate and supinate. They nevertheless still make a huge difference to the feel and efficiency of playing the piano. Bear in mind that, as the scales become  faster, the technique should change, and a different use of rotation becomes appropriate. The coordination given here would be suitable for semiquavers (sixteenth notes) up to speeds of about crotchet=160. At faster speeds the thumb will tend to move under less and will will find its notes more by means of a ‘rotary exchange’ (see reference under  point No. 9).   1. The thumb has played the C, with the help of a little pronation (anti clockwise rotation) of the forearm. This also helps to set up a mechanically advantageous angle for playing the E later on.
2. The second finger has just played the D. Note the angle of the third finger before the E is played. This is so that the finger can be driven directly into its note when the forearm    is rotated clockwise (supinated). Note that the second finger has played slightly on its side to make this possible.
3. The E is played by rotating the forearm (supinating) just enough to put the note down. Note that the third finger is almost vertical to the key, but not quite. The rotation makes the note and then stops immediately so that there is no superfluous movement. The thumb has travelled under the hand towards the F, but has not quite reached it.    4. The thumb is played by rotating the forearm back again (pronating). This brings the thumb the extra distance to reach the F and plays the note at the same time.       5. The hand begins to glide over the thumb as soon as the F has been played. The hand  and arm move in one piece — almost in a straight line. The second finger is now ready  to play the G. This will require no supination, as the movement should be saved for the fourth finger on the B. (Supinate on the finger before the thumb and pronate back when playing the thumb). I have not shown the G being played as it requires no special movement.     6. The A is played and there has been more pronation to move towards an efficient angle for the fourth finger to approach — and supinate into — the B, and also to help move the thumb further under the hand.  7. The arm pronates still further to provide a mechanically advantageous angle for playing the fourth finger and to bring the thumb still closer to the C.                      8. The B is played with the help of a strong supinating movement of the forearm. This provides a lot of power to a finger which often sounds weak — especially if the arm is already supinated before the fourth finger is played (as in some schools). Note how the fourth finger is driven straight into the key with maximum efficiency and that the rotary movement does not turn it beyond the vertical position. Any continued rotation beyond the vertical will tend to bring the finger away from the key, rather than into it and would, in this case, also bring the thumb further away from the C.  9. The arm pronates again as the thumb is played. The rotary movement has automatically started to move the rest of the hand further up the scale (the fourth finger is already nearly as far as the D). This is called a “rotary exchange.”                10. The arm and hand continue to move over the thumb as one unit in preparation  for playing D with the second finger — and we are back to where we started.   from "Musicians' Health"