Many piano teachers call the same physical approach to various passages by a different name. I find myself in harmony with author, teacher, composer, Seymour Bernstein when he demonstrates the "upper arm roll" in Part 4 of his recorded series, "You and the Piano."
As it plays out in one my teaching videos, I similarly refer to an "arm roll" that has a continuum of funneled energy through undulating wrists.
I also emphasize that the fingers have to be draped in a relaxed way, so as not to impede the smooth flow of energy down the arms into wrists, hands and finally into the fingers. This energy delivery should be without tension-related interruptions at any juncture.
In addition, I advocate the use of "rhythms" to activate these bigger energies where they apply. For instance in the Coda section of J.S. Bach Invention 13 in A minor, (end of measure 22 through m. 25), many students get "locked up," as a stream of Subject fragments pile up at close intervals. Often these notes within such sub-sets flow out of Dominant harmonies and land with ACCENTS instead of tapering according to harmonic rhythm.
To avoid such unmusical emphases, I suggest grouping notes in rhythmic segments with a natural arm roll into flexible wrists.
In the attached video, at the juncture where the A minor Invention spills into a climactic convergence of voices between the hands, commencing at measure 19, and continuing through an intensified spill (Treble 16th notes, against bass 8th notes) I further recommend a "rolling" or "wavy" contouring in groups of 8.
Finally, in reference to the uninterrupted flow of energy funneled down the arms, I urge students to preserve a mental image of "hanging arms, hands, and fingers." By standing upright and then bending over in a relaxed way, they can simulate this "feeling."
Even while seated at the piano bench, this same sense of "hanging" in relaxed abandon can be imagined and put to good use in piano playing, along with the related mental image of Puppet String Arms.
Original Content: The "upper arm roll" and undulating wrist in piano playing