Lately I’ve been having a real problem with broken octaves. I’ve noticed this after playing rondo alla turca and gewitter (thunderstorm), an AMEB grade 4 exam piece from the series 16 book. Whenever I try to play them at a relatively fast tempo, my wrist and forearm always tenses up. I’ve tried putting more emphasis on my wrist, using only my fingers, and a bit of both, and have tried relaxing my wrist as much as I can, but to no avail. My left hand doesn’t have this problem, I can play broken octaves perfectly fine. I don’t know how to fix this problem in my technique. Any advice would be appreciated.
You should not only use your fingers or wrist, but also turn your forearm to the left when you play with your left hand pinky and to the right when you play with your left hand thumb. Vice versa of course for the right hand.
This lady here explains it quite well: