Tomiki wrote many articles and books about Budo, mostly Judo and Aikido. In his writings, but also in his lectures he stressed a lot “shizentai” mostly translated as “natural posture”.
Shizentai is a posture neither limp or neither rigid. From shizentai we can move in any direction. If someone is pushing we can move away without changing the distance in our relationship with the opponent or partner.
The picture of Kenji Tomiki is sometimes used as “the” example for “shizentai”, but this is not completely correct. Shizentai is all about how your body is behaving during activity and rest. Tomiki’s picture is just one of many examples of shizentai.
Shizentai is a kind of neutral body structure, a balance between a tensed body structure and a slacked body structure.
Balanced body frame
A balanced body frame is not a fixed posture. It is a dynamic structure, and sometimes it balances between a 1-part body frame to a more multipart body frame. Both body structures are in a balanced status depending on the use of the structure in a specified situation.
It is also possible to have a “neutral” body frame, a structure when someone is touching or grabbing you and the opponent just feels your skin.
This kind of body condition is very convenient to hide your intention.
1-part body frame
A 1-part body frame is used when we have to increase “momentum” by using more body mass.
Using gravity in a movement is a good example of the use of 1-part body frame.
By stretching up the body, a 1-part body condition is created. When the body is tilted slightly forward, a forward step is needed to keep balance. Momentum can transferred into the strike with the “tegatana”. The attacking arm is a part of the 1-part body frame, the full body weight will increase the momentum in the strike. Of course, the skill of rolling foot and tsugi ashi is needed to keep balance.
Multi-part body frame
A 1-part body frame is very useful when we seem to have a lot of space to move around, but this is not always possible.
Our body has more possible options for moving and generating power. The skill of “rendo” is based upon using a multi-part body frame.
When the wrist is grabbed and twisted, the different parts of the body will allow the twisting. By allowing the twisting, energy is storing into the twisted body. This energy can be released by moving the different parts in a correct sequence.
The sequence in a multi-part body frame
It is important to keep the interface of the grasping unchanged. This is only possible when the body has a neutral condition. Opponent just feels the skin of your wrist, but opponent has no access to the rest of your body. You just accept his power which doesn’t interfere with your balance and moving abilities.
Keeping the interface
Do not resist or try to modify the situation. If you do, you change the state of the interface (the gripped part), and change is immediately detected by the opponent who will adjust the grip and hold you more firmly. Keep the interface as it is.
The change of the interface is an indication that you’ve used your consciousness to resist intentionally. You may use your consciousness to feel, but never use it to think or plan otherwise it will be detected by the opponent. Keeping the body frame neutral is an important skill for all Budo Aikido practitioners.
Untwist the body by itself
As the twisted body untwist itself by releasing the stored energy, your elbow drops and bends, and your palm turns upwards. You may think it is advantageous to step forward and turn to the antagonist to use the weight of your body for resistance, but you’re advised not to do so. Do not try to move intentionally, for it will be overpowered by the opponent who is in a better position, he’s twisted your arm already. “Keep the interface as it is” is important here as well, for as soon as you try to use your intentional power, the state of the interface changes and the opponent will notice it immediately.
The “real skill” of Shizentai
Shizentai is a dynamic condition of being. There are no unnecessary tensions, there is no slack in the body. All actions are optimal, even during the “rest” action. Of course it takes time to develop such a skill.
Shizentai is a skill useful in all aspects of life and it must be practised until it is a part of your being.