This article is much better understood after attending the masterclass dictated by Juan Rezzuto at WKMT. In other words, this article is meant to be used complemented Juan Rezzuto's masterclass on “rotation” movement.
The “rotation movement” is one of the most complex movements in the Scaramuzza technique. It involves the supinator and pronator muscles, the forearm, the palm, and the fingers primordially. The idea behind the application of this movement is to simplify the action so we can minimize the tension to the bare minimum.
In spite of the fact we will focus our analysis around the action of the supinator and pronator muscles, many other muscles will passively collaborate as a product of the activity of the aforementioned supinator and pronator muscles. The brachii, for example, will only act when we are practising - analyzing- the movement "in the air"; therefore they shouldn’t exhibit any sign of activity otherwise.
Creation of the movement
The main elements involved in this movement are the forearm, the pivot finger, and the focal finger.
This movement requires maximum control, particularly of our fingers. The only tension admitted will be the one at the pivot finger; this finger will support all the weight of the forearm and the rotation mechanism. There will be a certain degree of muscle “tonicity” exhibited by the non-playing-fingers and the focal finger as well. The latter can be described as a sense of rigidity which helps the hand to work as a plaque, or like a single imaginary finger that runs from pivot to focal point.
Understanding how the weight of the hand works helps us to understand the role of the leverage the palm excerpts and it transfers kinetic energy to the focal finger. In other words, the imaginary finger, we will aim to create between the pivot and the focal fingers, will be fuelled by the action of the supinator and pronator muscles transferred to the palm through the forearm -the palm itself being the “imaginary finger”-. Due to the latter is that we are in the position to say that there are two amplifying -leverage elements- involved in the rotation movement: the forearm and the palm.
The forearm is the origin of the movement; the place where the supinator and pronator muscles are located. The palm -moving only sideways- is the part of our body which expresses this movement the most.
The same as with the wrist movement, the rotation is a ¨spastic¨movement. The latter means that it needs to be used reflectively, meaning that once the movement starts, it can’t be stopped until its cycle is completed. We control the rotation, but both negative and positive movements occur in a single gesture. The latter gesture is what we will consider a movement cycle.
The rotation movement is eminently applied to “Alberti” basses and tremolo passages. Nevertheless, it can also be applied to certain jumps, attacking single notes and in combination with other movements.