The Second Top Ten Principles Of Yachigusa Ryu Aiki Bugei – #7 Coupling Principle

Since I first stated that the techniques taught at my school were based on principles, and that we focus more on understanding the principles that makes things work than the techniques themselves, people have e-mailed me asking me if I could explain these principles in more detail.

Last year I spent several months writing about the “Top Ten Principles of Yachigusa Ryu Aiki Bugei.” Now it is time to cover the next ten most important principles. Of course, one must keep in mind that while these principles are officially less important than first ten, in actuality they are just as important. The truth is that in many cases understanding and executing them properly is essential in order to make the “top ten” fully effective. In other words, they are just another piece of a very complex puzzle illustrating how sceintific martial techniques really are.

Unfortunately, trying to explain many of these principals in writing is very difficult, since many can’t be explained in words alone. However, I will try my best to describe these principles for the “blog” readers, using words, charts and pictures.

Keep in mind though, that in order to sometimes fully understand a principle you have to also understand other principles that relate to it. Most principles aren’t fully useable on their own, and have to be integrated with others.


Generally, coupling means a mechanical connection between two things. In physics, two systems are coupled if they mutually interact. There is another definition from computer programming that also seems appropriate to the art I teach: coupling is a linkage between two parts of a program such that if one part of the program is modified, the behavior of the other part may also be affected.

Basically, the coupling principle is the concept that once a connection is made between two or more bodies, whatever action one body makes will have a direct effect on the other bodies.

In other words, one plus one equals one.

For example, the square and circle below represent two individual objects:

If you move the circle, that movement has absolutely no effect on the square:

Now, let’s say you drive a stick into both the square and circle so they are connected to each other. They are now “coupled.”

If you push the circle down, the square will move also. In this example, the movement will be in the opposite direction as the objects rotate around their common center of mass.

Because they are “coupled,” whatever movement one object makes will affect the other. This is even more apparent when the connection point is rigid, as it is here. Needless to say, this is a crude example of a much more complex principle; but it explains the science that makes this principle work better than any other I can think of, at least in this format.

Maybe a simpler way of thinking about the “Coupling Principle,” is something many of us do outside the dojo–walking a dog on leash.

When I take my dog for a walk on the street we are “coupled” by his leash. Although there is no direct physical connection between our bodies–my hand is not touching the dog–by moving my end of his six foot leash in the proper direction, I can make my dog go left, right, or forward. Or I can make him stop and sit, down.

I don’t have to use verbal commands. If I adjust the tension on the leash the right way, because of proper training my dog knows what he is suppose to do–unless of course he sees a squirrel or a cat, then I’m on the receiving end of the commands and being dragged down the street.

What’s important to understand with this example is that I’m not using verbal commands.  He is responding to non-verbal communication through our couple. My dog reacts to the movements I make that affect the leash.

In this example, my dog he has been trained to respond a certain way to specific movements. But if I don’t move the leash correctly he gets confused and does not know what to do. My movements must be right to get him to behave the way I desire him to.

This is an important factor to remember because one’s opponent in a fight has received no training at all. This means when you use the “Coupling Principle,” your non-verbal communication–in this case “body language”–has to be specific, otherwise the other person’s body won’t know how to respond to your directions.

The basic rule one needs to remember about this principle is that once you’re coupled, any movement, no matter how subtle, has a direct impact on your opponent. Even rotating the head at the wrong moment can move one’s opponent inches off their original position. This is one reason why so many martial art styles emphasize the theory of “no wasted motion.”

Avoiding wasted motion is even more important when practitioners try to execute projections (throws), especially projections that rely on exacting alignments. Sometimes even the slightest, almost imperceptible movement can have drastic consequences.

This of course means that in order to execute the “Coupling” Principle at the higher levels one must learn “cause and effect.” In other words, one must know exactly what wll happen when any given part of the body is moved.

Example: Rear Shoulder Projection

Photo 1 – Two individuals with no connection to each other.

Photo 2 – As the uke (attacker) grabs the tori (defender) they become coupled. Even though the point of contact is small (tip of shoulder) a connection is made and tori can affect the ukes’ centerline.

Photo 3 – The tori lifts his shoulder (the shoulder only) and rotates slightly to the rear by rotating at the waist. Since both subjects are coupled, the lift and rotation pushes the uke off balance to his rear. If done correctly, uke’s hips come forward, creating a hole for the uke to fall into.

Photo 4 – The tori continues his rotation to the rear until the uke is totally off balance.
The shoulder is then quickly dropped straight downward causing the uke to fall into the space that was created during photo #3.

In addition, one must also learn the differences such things as turning the hand versus turning the forearm versus rotating the upper arm can cause. Try it; you’ll be surprised at the results.


Photo 1 – Uke grabs tori by the wrist.

2. Tori rotates his forearm (forearm only) towards the ukes’ arm. Since the tori and uke are coupled at the wrist, the rotation of the forearm causes the uke to come forward and downward. Note how the uke’s wrist has rotated around the forearm. (See below photos.) Also note that nothing has moved from the original position. The only movement was the rotation, everything else remained the same.

Learning all of these intricacies of controlling an opponent through coupling can take years, if not a lifetime to fully master. Add this complexity to the fact that in a real life or death fight numerous movements are taking place within milliseconds, each with the potential to change how one must apply the “coupling principle,” and one can start to see how difficult utilizing this principle actually is.

Fortunately, many of these issues are addressed in the techniques most of us are taught, though one must keep in mind that techniques taught in class often tend to illustrate ideal situations. That’s not a bad thing; it just means it pays to experiment. Nothing beats trial and error.

Oh, and if all of that isn’t difficult enough: how about coupling techniques that involve weaponry? Yes, even that sword on sword blocking action observed in so many styles is a form of coupling, which if the practitioner is skilled enough can be used to create a projection.

Just one more facet to think about.