Deconstructing Taekwon-Do

The Misappliance of Science: Problems with the Theory of Power (part 2)

Tony Montana's Theory of Power

Pictured: Not the kind of power we’re talking about.

I’m glad part 1 didn’t scare you away. In the first half of this article we looked at the scientific merits (or lack thereof) of most of the Theory of Power. In this half, we will break down General Choi’s thoughts on mass and speed. Considering he called speed the most important element in generating power, he does an exceptionally poor job of explaining the science behind it.

Keep in mind, I’m not a scientist. I’m just going on what I remember from physics classes in high school and university. If you find any issues with what I’ve written here, please let me know so I can correct them.


As with most of the other parts of the Theory of Power, Choi was sort of right with his musings on mass. Turning your hips and abdomen into a technique will increase the amount of body weight (mass, to be correct) you can put into it, which increases the power behind the technique. Likewise, using knee spring to get some assistance from gravity can sometimes increase the amount of weight you can put behind a technique.

Why do I say sometimes? Because if your technique is moving upward (like the upward punch in Hwa-Rang) then dropping your weight is actually pointless. If anything, you’re putting less body weight behind your technique. Knee spring essentially puts you into a short, controlled fall into your technique. With your front foot unweighted and your body weight falling, you can put virtually all of your mass into a technique. If you’re striking straight in front of you, to the side or downward, this assist from gravity can be a big help. But if your technique is moving upward while your body weight is sinking, gravity gives you no extra benefit.

It’s also questionable whether stationary techniques benefit from knee spring. Think about a punch done from sitting stance. Unless you’re punching downward, knee spring does nothing to help.

Notice I’ve been saying knee spring and not sine wave? That’s because sine wave is just exaggerated knee spring and really gives no additional benefit.

I also can’t help but point out Choi’s choice of words: “it is all important that the body weight be increased during the execution of a blow.” I understand what he means, but the words are wrong. You can’t increase your body weight without taking up something like bodybuilding or months-long Netflix binges while consuming bag after bag of Cheetos. What Choi means is that you should put as much of your body weight as possible into a technique (while still staying in balance, of course). If you put ¾ of your body behind a technique, you will hit much harder than if you only use your arm.


According to General Choi:

Speed is the most essential factor of force or power. Scientifically, force equals mass multiplied by acceleration (F = MA) or (P = MV2).

I won’t argue that speed is the most important element in executing powerful techniques. Whether we’re talking about force or kinetic energy, each of us only has a limited amount of body weight that we can put behind a technique. So the way to increase the energy delivered by a technique is to increase its velocity.

However, as with the other points in the Theory of Power, the general’s attempts at scientific explanations are a little off. First of all, P = MV2 isn’t the formula for power. MV2 isn’t even the formula for anything. Power is a measure of work done over time, so P = W/t. The formula for kinetic energy, which I’ve talked about earlier, is KE = ½mv2, or half the mass multiplied by the square of the velocity. Notice the lowercase letters? Those mean something. A capital “V” means “voltage.” A lower case “v” means “velocity.”

To give Choi some credit, later in the Encyclopedia he writes the formula for power as “P = ½MV2.” Sure, we know this is wrong, but at least he includes the “½” this time.

Choi would have correctly used the formula for force if only he’d used lower case letters for mass and acceleration. However, we have to remember that, scientifically, force, power and kinetic energy are all different things.

Force isn’t even the best principle to use to illustrate the effect of speed. For a force to be applied to an object, there must be acceleration, meaning that the object must either speed up or slow down. (For our purposes, because we’re talking about motion, we’ll ignore balancing forces that can keep an object stationary). When you throw a punch, you’re applying a series of forces on many parts of your body to ultimately propel your fist. You are accelerating your fist. When your fist hits something, it is slowed down by that object, meaning that your fist applies a force on the object (and the object applies an equal and opposite force on your fist). The speed of the punch doesn’t inherently determine the magnitude of the force. Rather, the magnitude of force is determined by the rate of change of the velocity of your fist. If your fist is travelling slowly and comes to a complete stop when it hits an object, you will apply a much smaller force than you would if your fist were travelling very fast and came to a complete stop. But, if your fist is travelling very fast and only slows down a little when it hits the object, not much force is applied because there wasn’t much of a change in velocity (i.e. there wasn’t much of a negative acceleration).

Downward motion

Next, Choi says:

According to the theory of kinetic energy, every object increases its weight as well as speed in a downward movement. This very principle is applied to this particular art of self-defence. For this reason, at the moment of impact, the position of the hand normally becomes lower than the shoulder and the foot lower than the hip while the body is in the air.

First of all, there is no theory of kinetic energy. Kinetic energy is a type of energy; there’s no theory involved. Perhaps Choi was trying to refer to the special theory of relativity, which states that the mass of an object increases the faster it moves. When an object is falling, its speed will increase due to acceleration from gravity, and as it moves faster, it will technically increase in mass.

Why do I say “technically”? Because at the speeds that a human body can move, even in a free fall, the increase in mass is so small that it’s imperceptible. This increase in mass only becomes measurable as an object approaches the speed of light. I don’t care how fast a person thinks they are, they will never be able to punch at the speed of light. So, in a practical sense, an object in Taekwon-Do does not increase its mass in a downward motion.

If an object can’t (measurably) increase its mass in a downward motion, then it certainly can’t increase its weight. Weight is a measure of mass and acceleration due to gravity. Because the force of gravity is constant on Earth, an object’s weight can only change once it leaves Earth. Actually, there is a second definition of weight that considers it to be a measure of the reaction force of the Earth on an object. This means that objects in free-fall are weightless because the Earth is not pushing back on them. So, if anything, weight decreases during downward motion.

Speed, however, can increase. As I mentioned above, when an object is falling, its speed will increase due to the acceleration from gravity. That object will accelerate even more rapidly when a force in addition to gravity is applied. But if a counterforce is applied and the object is lowered under constant speed (which is something we are able to do with our limbs), there is no acceleration, meaning no increase in speed.

The reason the position of the foot should be lower than the position of the hip while the body is in the air (depending on the kick) is because we can get most of our body weight behind the technique. Gravity does the work for us, and we are able to maximize the amount of force and energy that we put into the technique. When the foot is above the hip, we are fighting gravity to get energy into the kick.

Similarly, the hand should normally finish slightly below the shoulder because we aren’t fighting gravity as hard as we would be if the hand were above the shoulder. In this case, however, we aren’t getting an assist from gravity like we would when falling; we are simply able to better take advantage of our body mechanics and use less effort to overcome gravity.

Speed and reflex

Choi’s last section on speed deals with its relation to reaction time. Choi presented a strobo-photography experiment to measure the speed of various TKD techniques (he did like to try to make things look scientific, didn’t he?). According to the photo captions, it takes about 0.1 seconds to execute most kicks, which is faster than the average human reaction time (0.2 seconds, according to the Encyclopedia).

One problem with this information is that the kicks seem to have been timed only after they were already in motion. That’s kind of cheating, don’t you think?

The other problem is that, according to the logic of the Encyclopedia, “it is impossible for anyone to block these kicks unless he can detect them before the leg is lifted off the floor; i.e., know what kick is coming before it is executed.” This, says Choi, is why we must look an opponent in the eyes, instead of looking at the arms or legs. While I’m sure we’ve all experienced plenty of punches and kicks that reached us before we could do anything about them, even a little sparring experience can demonstrate that it is entirely possible to block a kick without reading your opponent’s mind. I’m not particularly great at sparring; I don’t typically know what kick is coming until it’s obvious, but I can still block my share of them.

A big part of sparring is trying to beat your opponent’s reaction time, but a block can be performed much more quickly than a kick.

It seems like something is off with this experiment, and my money is on the liberal time measurements. It seems as if Choi was using this experiment in much the same way as he was using the Theory of Power as a whole: to “scientifically” show that TKD is a superior martial art. It must be superior if the techniques are faster than normal human reaction time and TKD’s practitioners must learn to anticipate the techniques in order to block them. Never mind that, to the extent that this is true, it applies to every striking-based martial art as much as it does to Taekwon-Do.

So what?

So what’s the point of all this two-article-spanning nit-pickery? Taekwon-Do is still Taekwon-Do whether Choi had a solid grasp on science or not. The point is that weak science in no way improves the validity of Taekwon-Do. Whether the principles of the Theory of Power actually add power to a technique or not, poorly-explained physics won’t help anyone. If we truly want to help our students, we have to give them explanations that make sense and not simply point to the Encyclopedia and say, “Remember the Theory of Power” when a student isn’t doing something correctly (believe it or not, I’ve actually seen that done. Literally, the instructor pointed to the Encyclopedia).

The Encyclopedia of Taekwon-Do is an excellent guide. It is the blueprint for our martial art, and the product of General Choi’s life’s work (not to mention the work of the others who helped him along the way). But it’s not perfect.

Weak science in no way helps Taekwon-Do. So we should stop using it as a pillar of our martial art. Instead, why not strip down the principles to those points that make sense and use them simply as teaching tools? It’s time we stopped lionizing bad information.