A Chinkuchi Makiwara Exercise

Chinkuchi (チンクチ [cognate to Kinkotsu 筋骨]) is an Okinawan word meaning "Tendons/Muscles & Bones". It refers to the last instant before contact is made when the skeletal structure becomes correctly aligned, all the agonistic muscles are very suddenly and sharply contracted, and the muscles which stabilize the relevant joints are engaged to an appropriate degree. It differs from kime in that it doesn't involve all muscles equally and depends on structural alignment and stability from connective tissues.

A chinkuchi exercise: Starting with the fingers in contact with the pad, without drawing the relaxed hand back at all, the goal is to punch the machiwara with enough speed, force, and penetration to send the plumb-bob smashing into the ceiling. If done well, enough mechanical energy may remain to make the plumb-bob ricochet back into the board a moment later.