Just so anyone who reads these specific scans understands - Spamdini (the scanlator of Fist of the North Star for a majority of the manga series) used, and translated into English, scans of the first official French translation published instead of the scans of the original Japanese volumes; the...
From what I've gathered from the manga, The [Zoom Punch] involves a Hamon breathing technique that dislocates and stretches the joints to extend the arm and give it greater reach.
Because it's using The Ripple to dislocate the arm – that same Hamon energy dulls the pain caused by the move and...