If you have a Czerny 40 exercises handy. the 3rd exercise is on ascending and descending arpeggio's, left and right hand. There are other studies in there on arpeggio's but I haven't gotten to them yet.

To clarify, what Chopin is saying is don't ulnar or radial deviate but glide smoothly keeping the hand and forearm aligned.

I'm curious: when Gyro types at his computer, does he have coins on the backs of his hands?

Which if you are doing multiple octaves means you'll need to lean to the side to keep the forearm and wrist perpendicular to the keys. It's the twisting that causes trouble.

http://www.youtube.com/watch?v=3Tgkji6i5KA

was a fun link so I didn't mind the zombie thread

hi
that was my problem too
the solution for me was this
dont flex the thumb under palm
play c.e.g lik a chord 4 octave slow motion then increase gradually you have to use arm motion and shoulder muscles
then play the c.e.g in four octave very fast
never play it slowly because it is dangerous for thumb tendons
thank you