03 Toppling (Kuzushi)

Toppling is the action that leads to unbalancing. In this state the base of support is reduced to a line and the mass is tittering on a precipace. An object ( or person for that matter) is easier to topple when

    1. It has a higher centre of mass

    2. The base of support in the direction of the topple is narrow

    3. The mass is lighter. 

Points 1 & 2 can be manipulated but 3 is harder to change. See How to Throw someone for videos of this  and other concepts in action

A toppled object can generate no horizontal force ( ie cant fight back) and so becomes light to move an manipulate or turn.

Thus 

1. Achieving kuzushi in uke at the instant of contact mean the technique is already over and the battle already won. The rest is the busy work of technique that imparts the finishing skills of the art and allows experimenting with balance.

2. As uke if you can achieve kuzushi in nage you can defeat their techniques without effort.

Again this is the immovable body, we little old men can laugh at the techniques of others that are much lauded by masters and rarely explained.

Some of the above are explored in the application section. The figure below shows the toppling action on a body. Insert an uke into the box in front or side view to imagine your choice of technique, or a reduced subset / pure motion like aikiage

Toppling action

The optimum angle is at 90 degrees to the topping line. At this angle no energy is wasted pushing into the ground or expended into trying to lift uke up. instead there is a nice class 2 lever, arguably the most efficient for heavy lifting. We learn this through and as aiki age