On Tuesday, 10 November 2020, I gave a lecture to the Royal Asiatic Society - Korea Branch, in Seoul. The lecture occurred via Zoom and was recorded. Below is how the lecture was advertised, and below that is the YouTube link to watch the recording online.
Movement Characteristics of Korean Traditional Dance and Martial Arts
In this lecture, Dr. Sanko Lewis reveals several key characteristics that give Korean traditional dance and martial arts their particular “Korean flavor.” Through ethnographic research, Dr. Lewis identifies similar kinetic principles employed in the traditional Korean movement disciplines and discuss their cultural origins and technical functions. He also points out how attempts to appeal to a younger audience may cause a martial art to lose its traditional identity; for example, taekwondo’s inclusion of K-pop music and urban dance is eroding those characteristics that taekwondo shared with traditional Korean disciplines such as traditional dance. After this lecture, you will be able to identify the movement characteristics of Korean traditional dance and martial arts, which will enable you to recognize and have a better appreciation for the kinetic aspect of Korea’s intangible heritage.
I've spoken about the sine wave motion's relation to a bigger principle, which I refered to as the wave principle or circle principle before (see here). My admonition was that the "sine wave motion is an icon, i.e. a simplification, of the [circle] principle."
I recently found this illustration on Wikipedia, which depicts the "sine wave's fundamental relationship to the circle" and thought it would be good to post it here as well. The reason I believe it important is because people often become obsessed with the sine wave motion in Taekwon-Do, but do not realise the greater principle (i.e. the "circle principle") it is based on.
What's the point? Basically, the point is that "sine wave" in Taekwon-Do is more than just "bobbing" down-up-down when stepping. In fact, if your concept of the sine wave motion is limited only to stepping or sitting stance punching, you are clearly not understanding the underlying principle. The fundamental principle, of which the sine wave motion is one manifestation, permeates through all our movements. It is part of how we step, true, but it also involves how we chamber, what we do with our hands, how we block, why we rotate our arms when punching, why our techniques start with a "backward motion"; it is even part of our approach to joint-locks and throws. To properly understand the sine wave motion (or any other fundamental way of movement in Taekwon-Do), one has to understand this underlying principle that I call the wave principle, which can just as satisfactory be called the circle principle or Taegeuk ("yin-yang") principle.
"The wave motion is a rolling movement. It is continuous. In many advanced aikido movements, one can observe the rolling motion of the wave. The motion of the vertical wave movement is up-down, down-up, down-up-down, or up-down-up. One can also use the wave movement horisontally in an in-out, out-in, in-out-in, or out-in-out pattern" (p. 55).
Had you not known this passage came from an Aikido text, it would have been easy to mistake it for a quote from an ITF Taekwon-Do source.
Here is another quote with emphasis on using one's body weight -- yet another principle shared by both ITF Taekwon-Do and Aikido:
"Eventually, the student of aikido will become technically proficient but will gain the ability to use body weight to make his or her application much more effective and powerful. Rather than force a technique, the advanced student will set up the mechanics of the application and then drop his or her body weight into it. The strength of the entire body is stronger than just the arms. Bring the weight of your entire body, as relaxed dead weight, to bear in the direction of your training partner's kuzushi, or balance point, and it will make throwing your partner an easy task.
"Bending at the waist or using the muscular force of the upper body does not drop one's body weight. Rather, drop your weight by subtlely bending or buckling your knees. Accomplish all vertical movement in aikido by naturally bending your knees to lower you body" (p. 55-56.)
The Taekwon-Doist familiar with such concepts as the wave principle (i.e. sine wave motion) and the knee-spring action will notice the obvious parallels with the principles of wave movement in Aikido quoted above.
Again I affirm my conviction that ITF Taekwon-Do shares many concepts with soft style martial arts like Aikido.
When we look at the sine wave motion in its typically down-up-down form we can identify it as a vertical* sine wave. With vertical I mean that the wave oscillates up and down. This motion is usually used in order to drop body weight onto the technique and works excellent for techniques with a slight or strong downward angle like a middle section punch or a side-fist downward strike. This sine wave motion can also be used in an upward direction; for example, when one does a forearm rising block you move from a relaxed position to an upward position. The final drop of the typical down-up-down motion is omitted as it will act contrary to the direction of the upward technique. The (vertical) sine wave motion is therefore employed for techniques where the force of the technique moves either up or down.
The sine wave can also occur horizontally*; in other words, the wave oscillates from left to right or vice-versa. Usually when we talk about this type of sine wave, we refer to hip rotation or hip twist. Typically the hip is pulled back slightly and then jerked in the direction that the blocking or attacking tool needs to travel. Hip rotation is often part of a whip-like action where the different parts of the body are accelerated and uncoiled to create kinetic chaining. Techniques that benefit from a horizontal wave typically move horizontally, for instance a back fist strike or a knife-hand side strike.
Do we combine (vertical) sine wave motion with hip rotation? Yes and no. It depends on the technique. A technique like a wedging block that uses two forearms moving horizontally in opposite directions do not use hip rotation because it is impossible to rotate your hips both left and right to accommodate both arms. For a wedging block we only use vertical sine wave motion. The forearm rising block is also a good example where the main force of the technique goes up; for this technique a horizontal wave, in other words hip rotation, is downplayed.
There are techniques where the main angle of the technique goes forward and downward and can therefore benefit from both the forward hip rotation as well as body dropping through the sine wave motion. A clear example would be a diagonal downward elbow strike (as seen the pattern Juche) or even just a forward stepping middle front punch. The middle front punch reaches its target in a slight downward angle. A further example is the low forearm block, which moves both downward and to the side.
Actually, the simple rotation of the fist during punching is in fact the combination of a vertical and horizontal sine wave. The rotation plus forward motion creates a spiral or helix, which can be described mathematically as the combination of a vertical and horizontal sine wave. These types of combined vertical and horizontal wave forms can often be seen in ITF Taekwon-Do by the trained eye.
The important thing is to understand the direction of the forces created by these waves and also the force directions required by the various techniques you are using. Certain techniques benefit more from a vertical sine wave, in other words the typical sine wave motion, while other techniques benefit more from a horizontal sine wave, in other words from hip rotation. Using or putting emphasis on the wrong wave form should be avoided as it may nullify the power of your technique. Also, different parts of the wave benefits different techniques. One should not drop your body weight at the end of a rising block, nor should you raise your body at the end of a low block. Similarly the hip should rotate towards the target, not away from it.
Learning how to use the different wave forms is crucial in mastering ITF Taekwon-Do.
* Please note that my reference to "vertical" and "horizontal" should not be confused with the use of these terms in the ITF Encyclopaedia's discussion on ways of stepping. I'm using the terms here to describe whether we are viewing a sine wave as depicted on a Y-axis (thus vertically) or Z-axis (thus horizontally).
In my previous post on the wave principle I mentioned that it is not unique to ITF Taekwon-Do; that once you understand it you will notice it as being part of many martial art systems, particularly the soft style martial arts. In the two videos below, Aikido instructor Doug Wedell explains the "waveform" in Aikido.
The keen observer will notice very similar movements and ideas as we see and do in ITF Taekwon-Do. Particularly try to look for the sine wave motion, the down-up-down form. Mr Wedell explains this down-up-down concept in an analogy of bouncing a ball.
"Waveforms, look for them everywhere; they are in every Aikido movement," says Doug Wedell. To this I want to reply: "The wave principle; look for it everywhere; it is in every Taekwon-Do movement."
In my previous post I emphasized the importance of differentiating between the sine wave motion and the wave principle. While I spent some time explaining what the sine wave motion is, I did not go into that much detail regarding the wave principle.
The wave principle is a much more abstract concept and therefore harder to define. To begin with, not all martial arts refer to it as the “wave” principle; it is often referred to as the circle principle or the Law of Change; that is, the Taegeuk (Tai-Chi in Chinese), i.e. the concept of Yin-Yang.
To understand the relationship between a wave and a circle, it is important to know that a wave is basically the rotation of a point on a circle plotted over a path in time. The video below (similar to the image above) illustrates how a circle and a sine wave are related.
(See this video for a more detailed mathematical explanation of the relationship between a sine wave and the unit circle.)
Were you to change the perspective of this sine wave and view it in 3D you may see a helix (spiral) or a circle or even the Taegeuk. The animation below effectively demonstrates this.
So when one speaks of the wave principle, one is also meaning the circle principle or meaning the Taegeuk, which of course includes notions of hard and soft, offensive and defensive, firm/push and yield, and so on. It would be appropriate either way to speak of the wave principle or circle principle or Taekgeuk principle. They are all essentially the same thing, each just emphasizing a different aspect. When we discuss the circle principle we are probably stressing the rotation aspect. When we discuss the wave principle we are probably stressing the movement over a specific distance. When we discuss the Taegeuk we are probably stressing the interplay and oscillation of opposites: up and down, hard and soft, pushing and yielding. For the sake of simplicity I mostly just refer to it as the wave principle because it is so conspicuous in ITF Taekwon-Do’s sine wave movement; although it is present in many more ways throughout ITF Taekwon-Do and easily recognizable to anybody who understands how this principle can be expressed.
The wave principle encapsulates everything that is true of a circle. There are no sharp edges or rigid corners. Since there are no corners, a change in direction occurs smoothly via curves. When doing the sine wave motion, the practitioner is admonished to keep the wave smooth and natural; jerky motions are to be avoided.
The idea of a wave brings to mind rolling valleys and hills, ocean waves rising and dropping. The wave principle, as embodied in the Taegeuk, forms part of the Do ("Tao," in Chinese) meaning the natural Way of the universe. A martial artist wants herself to move as part of the Way, but try to get her opponent to move against the Way. She can achieve this through different means. She could uproot him, an approach often used in Tai Chi Chuan which involves breaking his balance. In Judo, the Judoka may actually lift her opponent of the ground to uproot him and so break his connection with the earth, placing him contrary to the Way. In Taekwon-Do one might employ a rising technique or unbalance the opponent with Taekwon-Do’s many (and highly underused) sweeping, checking and pushing techniques, in order to break his connection with the earth or the Way. Or she could do the opposite and instead of uprooting him, press him “into” the earth. According to one Taekwon-Do commentary, when hitting your opponent you should become part of the earth so that “your power amounts to that of the earth’s crash against him” (Philosophical Principle of Taekwon-Do, Chapter 34). You can do this by dropping your technique into the earth, moving and working with gravitational force -- many of Taekwon-Do’s techniques works on this principle; after the Judoka has uprooted her opponent she then crashes him, i.e. throws him, against the earth. However, to move “down” one has to have been “up” first.
It is my opinion that if they were to recognize the sine wave motion for what it is, a manifestation of the wave principle as found in many other martial arts like Tai Chi Chuan, Aikido or Systema, a greater degree of understanding and maybe even an appreciation of the sine wave motion would follow.
There are a number of critiques against ITF Taekwon-Do’s “sine wave”. Some of these critiques are based on a misunderstanding of the (sine) wave principle. A common misunderstanding arises from people seeing the sine wave motion as an end in itself and not realizing that it is in fact merely an expression of a greater principle. When talking about “sine wave” it is important to differential between the sine wave motion and the wave principle it is based on.
If you are unfamiliar with what we usually mean by "sine wave" in ITF Taekwon-Do, basically it is the way we move in a kind of bobbing fashion using the knees ("knee-spring"), as if moving over a waved path. The simplest expression of this is known as the "sine wave motion" and contains an initial downward phase, an upward phase and a final downward phase. It is thus often explained as "down-up-down." In truth, the purpose of the first downward phase is not necessarily to go down; it is merely a deliberate act of relaxation in which the limbs and mind is consciously relaxed. From here the practitioner will then lift his or her body to gain potential energy and finally drop the body into the technique and in so doing converting the potential energy into kinetic energy. Basically the aim is to have more of one's body weight behind your technique as this increases the momentum of the technique.
Notice how the ITF Taekwon-Do practitioner performs the sine wave motion in the pattern Won-Hyo below.
For a more detailed explanation of the sine wave motion, read the related article at Taekwon-Do.Net.
The basic sine wave motion ought not to be confused with another related concept, namely the (sine) wave principle. I will henceforth refer to it merely as the “wave principle.” The sine wave motion is an icon, i.e. a simplification, of the wave principle. The sine wave motion is almost always seen in its basic relax-up-down form; however, the wave principle transcends this rigid confinement of three phases. The wave principle could sometimes be seen as a reversal, for instance up-down-up; or it could be expressed horizontally, for example as left-right-left; or even cyclically. It need not have three parts, but could only involve up-down, or may oscillate numerous times. It is recognizable when boxers bob and weave, or when you naturally extend or retract a limb to maintain balance. If you understand the wave principle you will notice it in throws and joint locks. It forms part of how we accelerate our techniques through kinetic chaining, sometimes referred to as sequential motion. A “wave” occurs every time you breathe in and out. You may depict it as the Taegeuk (the yin-yang symbol) or as the Sam-Taegeuk, Korea’s three lobed yin-yang symbol. The wave principle is not unique to ITF Taekwon-Do. It is found in many martial arts, particularly soft style martial arts. I’ve encountered it in books on Aikido and Hapkido and have seen it applied in Chinese soft styles like Tai Chi Chuan and Russia’s Systema. The wave principle is characterized by conscious relaxation and motions that move along curves, rather than rigid linear movements.
The iconic relax-up-down sine wave motion was General Choi Hong-Hi’s ingenious application of the soft style wave principle into the linear hard style Karate-based movements from which Taekwon-Do was sourced. Through the sine wave motion the soft style wave principle is infused into the previously hard style movements. It would be incorrect to say that ITF Taekwon-Do is a hard style martial art. Similarly it would be unfitting to call it a true soft style martial art. It has become an interesting hard style-soft style mix that uses hard style techniques, but performed with soft style principles.
Differentiating between the sine wave motion and the wave principle on which it is based is crucial when one tries to speak (and critique) the sine wave motion in ITF Taekwon-Do’s basic movements.
and is equally relevant to ITF Taekwon-Do. 
