The first phase of a throw is called Kuzushi. Kuzushi will break the balance of UKE into the direction in which he will be thrown with minimum effort.
|TORI has to bring UKE's center of gravity outside from the footprint of his feet. The balance of UKE is broken, when the plumb line of the CG (center of gravity) is located outside of the pillar area. The vertical position of UKE is then so modified that UKE is no longer able to return to a stable vertical position and therefore he falls over. Kuzushi create the ideal conditions for the successful execution of subsequent phases of throwing (Tsukuri, Kake und Nage).||
||Important for all actions of TORI is the use of the entire body. For example TORI uses feints (feinting of a throw); a movement, for example by a fast and powerful pull forward, is deceptive, UKE responds accordingly with an equilibrium displacement of his center of gravity to the rear. This reaction of UKE is now utilized for a backward technique (e.g. feint kata seoi and throw Ko soto gake). Normally the balance can be broken into eight different directions: back, forward, left, right, and the respective four intermediate directions.|
The knowledge of physical principles will be a great advantage for TORI: The disturbance of UKE's balance can only be achieved by the use of appropriate forces (muscle forces, inertia forces, gravity, torque, and so on). The balance break should not be a hectic tugging or tearing at the judogi of UKE, but caused by the body's own power. The basis of the balance breaking consists in the opposite pushing and pulling (pair of forces), this is happening not only with the arms, rather with the help of the TORI´s entire body.
From a physical (mechanical, static) view the balance of refraction depends in part on the following factors: