The body’s muscles are as strong as steel, yet flexible in this condition. The feeling is cat-like. The best example of this is seen in Kururunfa (久留頓破) when dropping into Koshi Dachi
(腰立ち) and then immediately spring up into Zenkutsu Dachi (前屈立ち). Development of fast springy movement is necessary to develop strong suri ashi and agility as seen in the practice of Sayu footwork in cat stance. Kongo Ken is used to develop the particular muscles especially when doing two handed overhead thrusts. Ten Tsuki helps to develop the coiling and releasing training for the muscles to develop Chiru no Chan Chan. By dropping and rising quickly during the exercise one learns how to control muscles by releasing and contracting quickly. This also leads to a fast ’springy’ movement. In Sanchin Kata, one develops control over Tanden (丹田) strong contraction of the muscles in the lower abdominal region which leads to explosive control in this area.
By being able to physically change from one height to another or moving in one direction to another by coiling up and storing energy in muscles to create an explosive cat-like movements is what makes the characteristic of Chiru no Chan Chan.