How should I position fingers 1 and 5 in these preparatory exercises from Cortot?

Question

The first two are from Cortot's preparatory exercises for Chopin Etude opus10/1...

My hand cannot reach a 10th so I have to reach and sort of 'jump' to the upper part of the chord. The first exercise seems the bigger challenge where my wrist sort of 'swings' to make the reach.

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EDIT

I removed the example for Etude No.7 to focus on the thumb issue in Etude No. 1.

I found this slow-motion video of Cortot's hand. Althought I don't know what is being played, because it is silent!

Cortot's thumb is obscured by the angle of the camera view, but it looks like he releases finger 5 quickly and does not contract his palm to move the thumb up to the next key.

When I say contract I mean this...

...where I'm holding finger 5 on the E key while my thumb is moved to the C key. I have to squeeze or contract my palm to get the fingers to the keys in this manner. As if my fingers walk along the keyboard like a spider.

By comparison, if I don't contract my palm I have to rapidly shift my hand position up the keyboard. It's sort of like maintaining a 5-finger position and not contracting and stretching my hand, but shifting my hand position from my arm...

I'm not really sure how to handle this, because I see this video where clearly the pianist is contracting his palm to bring fingers 1 and 5 close together...

Answer 1

No, your hand size don't hinder you as it is not necessary to play a 10th in this exercises. I started the same etudes only some weeks ago and I didn't know about Cortot and Godowsky. The most important point is that you really jump with your hand very quickly from octave to octave and don't think to go with your thumb under your hand (what usually is most important for scales and arpeggios.)

The wrist has to move in a circle and your whole body above the seat is moving in circle from the left to the right and to the front and back. If you still keep hanging on a key with your fingers play the music in other keys like B major or Db major, (I have invented some own exercises: one of them is to jump with the only the thumb from C to C or just play with the index all G across all octaves or play only the 3rds c-e with ring finger and pinkie finger.)

The movement has to be as fast as a glissando and the thumb as to follow the whole hand, the whole right arm and elbow are involved in this movement.