Activity and Passivity in Piano Technique

Bodily movement may be caused in two ways:

1. by voluntary
2. or involuntary contraction of muscles

through neural stimuli^[1], or by the action of some outside force upon the part to be moved. If I lift my arm with the idea of reaching for something, the movement is the result of muscular contraction.
This is called an active movement. If, on the other hand, another person takes my arm and lifts my arm into the same position, the movement is the result of the action of the force supplied by the other person, therefore the movement is passive since I am not doing any work. The movement made by the other person in order to bring my arm into the desired position is an active movement.
If conditions were reversed and I should be lifting his arm, I should be making the active movement and he would be making the passive movement . The difference in the muscular coordination between these two types of movement has a most important bearing upon problems of piano pedagogy. For here the teacher very frequently moves the pupil's arm, hand, or fingers through the desired movement. It is advisable to learn whether in so doing the actual muscular reaction of the pupil is the same as that made when the pupil performs the movement unassisted, or whether there are differences.
If there are differences, what are they.

There are several ways of learning this. Following the plan of procedure adopted in other modules I shall first treat the theoretical phases and then correlate these conclusions with actual records obtained of the muscular contraction in both types of movement. In the module on coordination we shall learn that economy of effort. We may call it the law of least effort, because it is the fundamental requirement of a coordinated movement . Nature would defeat its own purpose, therefore, if an organism making a passive movement expended the same amount of energy as when the same movement is made actively. If we return to the example of arm lift described in the preceding paragraph, if it takes ten units of force for me to lift my arm into the desired position, it will take at least ten units (and necessarily more) for someone else to lift my arm.

But any element of this ten units of force that I expend while my arm is being lifted is superfluous energy, since the outside agency is capable of doing the work. Accordingly, we may expect to find at least less contraction in passive than in active movement. And since any participation is unnecessary, no contraction whatever would be the most economical procedure and would most closely follow the law of least effort, since any contraction^[2] no matter how slight, involves some effort.

[1] neural stimuli:A neural stimulus is a hormone that is released by the glands of the endocrine system. This is a non-voluntary process in which the nervous system stimulates the endocrine system to release neural stimuli.

[2]contraction: Muscle contraction is the activation of tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding 30 pds at the same position.