Seichusen & a column full of power

It is the Earth which allows to generate force with the legs.

Internal Martial Art


In “Aikido-Tradition and the Competitve Edge” written by Fumiaki Shishida and Tetsuro Nariyama the definition of “Seichusen” is as follows:
The human body displays bilateral symmetry. Seichusen is a vertical line through both the nose and the navel down the center of the body that cuts into two exact halves.

Of course, this definition gives us just a 2D image, whereas our body is a 3D object. The idea of bilateral symmetry is right if you see the body of the front face. On the other hand, another point of view does not follow the bilateral symmetry.
A view from any angle at the seichusen can be seen as the center line which divides the body into 2 halves. These 2 halves are not symmetrical, except for the front or back view.

A column full of power

Seichusen or the centerline always stretches in the direction from top to bottom. This creates a line of strength needed for good posture.

A strong position is not only with the vertical line, but in a horizontal plane as well.

The centerline should be viewed as the midline of a column. This column can be very thin, but can also be very broad and full of power generated using the legs.
The column strength lines are oriented in six directions.

  • Up and down
  • Forward and backward
  • Left and right

A column full of power is embedded in the various postures and positions we can adopt during training.

An example of how Seichusen works.

Testing posture with footwork

Footwork is a basic skill to perform effectively while exercising. Maintaining a strong yet flexible stance is a condition for moving when an adversary is involved.

Mu-gamae & Hanmi

Mu-gamae is mostly translated as empty posture or no-posture. In fact, when you just are in a standing position with parallel feet and your arms at the side of the body, we can consider this as “mu-gamae”. There is no intention in this posture.

There are 2 important control centers

  • Kyokotsu – upper center
  • Hara tanden – lower center

By moving a foot forward and turning the body, we create a stance mostly named as “hanmi” (half body turn).
If one thinks about Aikido as Budo, then it is necessary that one considers mugamae, right position (hanmi) and left position (hanmi) as 3 in 1. The 3 basic modes have of course an integrated seichusen and the column of power.

“Hanmi is efficient when you step in from mugamae to the opponent or when you want to apply a technique. But as a starting position, hanmi is not very useful.”

Kenji Tomiki

3 types of hanmi

Using hanmi has 3 modes. Each mode is associated with a type of movement expressed by the bodyweight transfer.

  • Neutral position, bodyweigth in the middle
  • Forward position, bodyweight forward
  • Backward position, bodyweight backward

Generating strength with the legs

Essentially, all of our strength comes from our legs. It is initiated from the lower body and then moved by the hara tanden to kyokotsu and distributed to the hands.

When you push with your legs down, there is a rebound, which is guided with your knees in your hips. They must be flexible and do not brake.
The role of the knees is important, these joints move toward each other during a forward motion. With a motion to the back, they separate. Knee motions are measured in millimetres.
Moving forward, the front leg and knee move downward. As you move backwards, your back leg and knee move downwards.
Don’t forget to fold your hips as if sitting on a high stool.

Hara Tanden and kyokotsu

Tanden and kyokotsu are two centres used as a distribution tool for the force generated in the body through the use of the legs. Find more information in a different article about kyokotsu and hara tanden.

Moving with tegatana.

All power generated by the legs has to be transferred to the hand and/or arm. The tool we use to transmit our power to the target is tegatana.

What is Tegatana?
When the 5 fingers are stretched enough, the base of the hand is stretched overflowing into the little finger. In the small sense this is called tegatana, but in a broader context this becomes the forearm (from wrist to elbow). Tegatana exercises include both hand length and arm length exercises

Tegatana no kamae

This is an extension of mugamae and hanmi (hidari/migi no kamae)

3 types of tegatana no kamae

These are chudan (middle level), jodan (upper level) and gedan (lower level), where chudan is used as a basis where the tegatana is kept in the seichusen (centerline) of the body

3 conditions for movement with tegatana

  1. The use of posture with correct stability.
  2. Positioning the tegatana in relationship with seichusen or correctly on the center line of the body.
  3. To ensure that the use of the tegatana corresponds to the foot movement carried out at the same time.

Opposing isometric forces

The human body as a movement construction is used by most of the people in a very inefficient way.
The body and mind are full of tension and this creates during a movement action sometimes a non-movement situation: a frozen action.
People think this can be resolved by relaxing the body and mind. Unfortunately relaxation is understood as a lack of tension resulting in collapsing body.
During a fight or in our case randori, we cannot have tension or relax. We need to find another solution based upon the concept “tone of the muscles”.

Balancing between tension and relaxing: Opposing Isometric Tension

Yi-quan* is a Chinese martial art famous for Zhang-zuang (Ritsuzen in Japanese) and the use of opposing isometric forces (zheng-li). Other Chinese martial arts are also using these concepts in a more or less manner during their training. The Japanese version of Yi-quan is called Taikiken and is utilizing many concepts borrowed from Yi-quan.
In Japanese Budo we certainly can find countless examples of “opposing isometric forces”.
Nobuyoshi Tamura**, an Aikido teacher used Baduajin or 8 brocade exercises as a tool to improve inner power. One of the concept in Baduajin is “opposing isometric forces”.

**I studied aikido during my early period (1970-1978) with Tamura sensei, Kanetsuka sensei, Kobayashi sensei – see also Intro
* I was introduced to Yiquan by Ilias Calimintzos (France)

Budo and opposing isometric forces

In Kodokan Judo there are many kata to explain the concepts of Kodokan Judo. One of the lesser known kata is “Go no kata”.
This kata has many “opposing isometric forces” to keep a power balance between Tori and Uke. It expresses very well the concept of “Go” as a counter concept of “Ju” found in “Ju no kata” and other Judo training tools.

Tomiki Aikido has many exercises to develop this kind of power. Even in other styles of aikido, this kind of exercises is frequenly used as mentioned in a previous paragraph.

Tomiki style opposing isometroc forces

From “Gendai Aiki”

Koichi Tohei famous unbendable arm can be classified in this category.

What are the thoughts of Kenji Tomiki on this matter?

Kono mondai wa, gendai taikugaku no, kinniku toreiningu no koto de, isometorikkusu to iun desu.
This is a matter of muscular training which is part of modern physical education. It’s called isometrics.

Sore wa, oshitari hiitari suru koto ni yotte, kukkin ya shinkin ga hataraku wake desu ga, jouzu ni naru to, kinniku ga hataraku no wa mienain desu.
That is to say, we can train inner or outer groups of muscles by pushing or pulling. A person who is highly skilled at this form of training hardly exhibits any muscle movement at all during the exercise.

見えないところで筋肉をうまく使えるんです。しかし、それ(このような理論を隠しておいて、大道の安芸人のようなことをすることをさす)を教育の場にもってきたら、非常に おかしい事になってしまうんです。
Mienai tokoro de kinniku wo umaku tsukaerun desu. Shikashi, sore (kono youna riron wo kakushite oite, oomichi no akibito no youna koto wo suru koto wo sasu) wo kouiku no ba ni motte kitara, hijouni okashii koto ni natte shimaun desu.
When you can’t see any movement the person is using his muscles very skillfully. But you are making a big mistake in the educational field if you demand a similar level of expertise from everyone.

Interview with Kenji Tomiki – Aiki News

Opposing isometric force pairs

The steering of a movement is the result of a neuro-muscular action. This action has 2 main components:

  • The use of internal and external factors: body and gravity
  • Using the mind as the manager of the internal and external factors

Movement of the body need always a support point and in most cases earth is the major support point. The mind is observing the body which is build according a vertical line in relationship with gravity. The mind is not interfering with this body action. Keep in your mind, standing is a movement.
Feeling with the feet the solidity of the earth, feeling the returning (rebound) power of gravity towards the head. Keep this stretch because this is the opposing isometric force by using gravity and correct body posture. Tanden (hara) plays an important role by becoming the center of the body. Gravity is always present even in non-vertical force lines.

Major opposing isometric force pairs are:

  • vertical line
  • left/right line
  • forward/backward line
  • diagonal line
  • combination of major lines

After developing major opposing isometric forces lines, the next step is to be applied them during movements. Keeping the isometric forces lines is a real challenge and we cannot expect an immediate result during training. Mind and body must become one and “ego” or “the monkey brain” ** cannot interfere with our movements, mentally or physically. Reaction to an attacking movement by an opponent must be handled by a spontaneous reflexive action.

**Taming the “Monkey Brain”
We all experienced the noise in our head when the monkey brain is talking during our exercises. Stopping thie noise is not a solution, because the monkey brain is not listening. Better is to ignore the noise, and after a while you will notice “the noice is gone”. You really start to feel the exercise and the dynamics of the body. This is forging the body and mind. It is not about bigger muscles, or more muscular strength. I can feel my body and its movements…..the rest is a side issue

How to develop opposing isometric force pairs

Opposing isometric force pair is a state of equilibrium between two tensions. If the two forces are equal, a balance is established between them.
This implies this form of tension inside the body which solicits two distinct zones. If we consider our body as a dynamic system, all types of force will involve the opposition of two forces regardless of direction.
For example, when you jump up, you use a force to hoist yourself up. You can also say that you exert a force down (ground).
To achieve upward movement, use the downward force. Similarly, to achieve a forward movement, it is necessary to exert the force towards the back.
We can interpret the function of the legs as that of spring which makes you bounce in height when you make a push towards the ground. This image speaks easily of the movement of legs that function as a pair of springs.
Let’s now look for the mobility of the trunk whose examination is fundamental to understand what an opposing isometric force pair is. The mobility of the trunk is not very visible, which makes it difficult to place the image of spring in relation to the movement of the legs. But the function of the trunk is crucial to organize the application system of the overall force of the body.
Like the springs of the legs, imagine that at the level of the sternum – kyokotsu – existed a spring that goes inwards to its antipode back. Following this example, let us situate imaginary springs inside the trunk to zones corresponding approximately to those of the chakras in yoga. These are in addition to the sternum, under the throat, plexus, navel and lower abdomen. All these springs are placed inside the trunk and their other end rests on the dorsal projection of these five points.
By putting the mind on the kyokotsu or other points of the body, we can move the kyokotsu in this example forward and back and use the image of the spring to create resistance.
The spring image can be internal, but can also have an external quality. If we use a spring connected between our elbows, we can open or close our arms and feel the resistance between the elbows.
A step further is to use the spring image between you and your training partner.

Developing spontaneous reflexive action

Reflexive action conditioning is primarily neuromuscular coordination training. You must have a firm foundation in multi-directional awareness before you can start this training. The goal is to achieve mind-intent and body action arriving simultaneously.
Internal movements during solo training can give an impression of “no movement” when there is no external movement visible. It is called “pause”. Posture training – ritsuzen – is mostly internal movement training wihout visible external big movements.
When doing moving exercises start always slow and use rather big movements.
Tegatana dosa, also called tandoku undo, are exercises to build this skill using the change between the different body (arm, hands,….) movements.
After many repetitions and using correct body movements with mind-intent leading the action, it will become a spontaneous reflexive action under control of the mind while maintaining the isometric tension.
Next step is to use these movements in paired exercises and all kinds of randori.


Defending the centre line

Seichusen, the centre line.

The centre line is the vertical line which marks the centre of the body. We use our centre line as a guide in our practice. Basically, our hand should not move over the centre line to the other side of our body.

The centre line is important in order to keep our central equilibrium.
Central equilibrium can only be achieved through correct and diligent training by always lifting up our head top, and pressing our feet into the ground. This skill can be improved by practising “posture”, also called “ritsuzen”.
With strong central equilibrium, we can absorb or redirect the incoming force, and countering very quickly. In short, our defence or attack will be much more efficient if we have strong central equilibrium.

The more we deviate from the centre line, the more our central equilibrium will be subject to muscular tension to keep our balance. Our body will respond automatically to such situations. There are 3 options:

Ankle action
Hip action
Stepping action
  • Ankle action will happen when practitioner keeps his body under tension.
  • Hip action is basically trying to drop the bodyweight, but by keeping the knees stiff the hips will bend.
  • Stepping action will occur with unexperienced practitioners, but is also a strategy of an experienced practitioner. (see Unsoku-ho and tai-sabaki)

Experienced practitioners keep their body in the vertical line (centre) and will use tenshikei, Keeping the joints flexible and strong is an important body condition.
Tenshi is a rotational skill to absorb incoming power and redirect it to the opponent.

The previous example shows you the stiffen up of the body trying to defend against the action of Tori. To avoid further “kuzushi”, Uke steps but the upper body is halted by the arm action of Tori.

Defending the centre line

Basic posture to defend “seichusen”

Defending the centre line is an important concept and can be applied in different situations. We can distinguish 2 major kinds of defending the centre line.

  • Passive method – using tegatana as a shield
  • Active method – using tegatana as a weapon

Passive method

By keeping “tegatana” in front of the centre line, opponent have difficulties to attack your centre.

The sword is an extension of the tegatana and is protecting the centre.

In tegatana-awase, a multipurpose exercise, tegatana is used as a shield and prevent a straight movement to the centre by opponent.

Active method

In this method, we use “tegatana” as an active tool. Ridatsu-ho and seigo-ho are methods to defend yourself against grasping attacks. Free hand tegatana can be used to apply an atemi on the centre line of other vital point of the opponent.
What kind of atemi will depend on the goal you are looking for. Be the fact that we are going to throw the opponent or that we want to apply a shock to the body.

Vital point – Judo & Aikido/Kenji Tomiki

You will notice, the centre line has many vital points and can be used in self-defense situations.

Body movement exercises & centre line

We mentioned tegatana-awase in a previous paragraph and how to protect centre line with tegatana.
Of course there are numerous body movement exercises and basically protecting the centre line or attacking the centre line is included. Also remember the importance of the centre line in keeping the central equilibrium. When we lose our balance, in most cases we also will lose the protection of the centre line.

Tenshi exercises
Solo and paired tenshi(kei) exercises are an integral part of the regular training.

Unsoku-ho – defending by stepping

Avoiding an attack by stepping is a strategy to bring the mind and body into a position where the attacking power cannot get hurt.
On the other hand, stepping is not running away from an opponent.
It is important in order to control the situation, physically and mentally.
The concept of ridatsu-ho and seigo-ho is in fact an extension of stepping. It is avoiding and/or controlling the power of the opponent.
The exercises of unsoku-ho has to be considered as tools to study breaking away and/or controlling an attack of the opponent.
This can be punching, striking, kicking, grasping or any action from opponent to hurt you or control you.

Avoiding an attack

Avoiding an attack needs to take in account the concept of “Sen”. Running away is not always the correct method because there is always a chance opponent is much faster. There is also the mental side of running away or not running away. This can be of course the subject of another blog-post. We do not wish to become frustrated because we are afraid of a confrontation.
During avoiding an attack our body and mind must be in a state of defending/attacking mode. To create such a state of being, the study of “opposing isometric forces” can be very helpful. Subject of another blog-post.