Playing Octaves Effortlessly

When playing an octave, let the piano open out the hand. If the brain records a feeling of stretch in the muscles, it is a sign that playing 1) down and 2) across is happening at the same time. When the rotation of the forearm is added there should be no feeling of moving across. The brain tends to record only the sensations of playing, during the act of key depression and there should be no feeling of movement in any direction.

The walking arm is a potent tool in playing consecutive chords and intervals, for it removes the burden from the fingers when combined with rotation. It must be repeated that only the forearm be used for walking arm.
If the upperarm is involved severe pain can result.

If a man is walking and there is a wall, the only thing you can see is his head moving up and down because he is walking.
Walking arm helps the hand to bring every finger down. When you practice the walking arm, exaggerate the up and down motion with rotation. Eventually the walking arm disappears visually and only exists physically.
Walking arm is the up and down movement of the forearm combined with rotation. The first time you employ walking arm, you exaggerate the movement to get the correct sensation. In piano playing, your ultimate goal is that everything is effortless and walking arm is a way of getting your fingers to play in a coordinated manner. Walking arm uses a combination of the "up and down motion " with rotation.