This topic comes from a YouTube viewer of mine who was responding to a video I made about a Brilliant Piano Technique.
My piano teacher today told me that lifting those middle 3 fingers up and out of the way causes enormous tension all the way through your arms and that while playing octaves, you need to rest your middle three fingers on the keys in a relaxing position, directly contradicting your video. Please help me!
– Youtube Viewer
Your teacher is absolutely correct in directing you to keep your hands as relaxed as possible. The fact is, playing octaves requires strength. Without that strength, it is impossible to play rapid octave passages. If the fingers are not out of the way, they will hit notes between the octave. So, it is necessary to have a hand position that allows for clean octave work. You can see a demonstration of how this can work in a Liszt Hungarian Rhapsodie.
When I was young and developing my technique, it was exhausting practicing this piece. I have extremely small hands that are naturally very weak. However, with progressive, intelligent practice, it is possible to develop strength and speed by utilizing proper hand position in the most relaxed manner possible.