Deconstructing Taekwon-Do

The Misappliance of Science: Problems with the Theory of Power (part 1)

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Almost every Taekwon-Do instructor I’ve met has touted the values of General Choi’s Theory of Power like it’s the heart of Taekwon-Do. The Theory of Power defines our martial art almost as much as the techniques we do. Choi wanted Taekwon-Do to be a powerful martial art above all else, and the Theory of Power acts as a guideline to shape the techniques and extract every last ounce of that power. Not only that, but it uses science to show how Taekwon-Do is a superior art.

That’s the thinking, anyway.

The problem is that Choi’s science is questionable, at best. Even when the underlying principles are correct, his scientific explanations often are not. In other cases, such as his thoughts on reaction force, the principles themselves are wrong.

Much of my criticism has to do with Choi’s use of scientific terminology, like his often incorrect use of the word “force.” I understand that in everyday language we don’t stick to strict scientific meanings. But the entire point of the Theory of Power was to give scientific merit to TKD. If that was Choi’s goal, he should have at least gotten his science right.

I’m no physicist by any means, but I’m going to try to use my knowledge of high school-level physics to point out the issues I have with the Theory of Power. Why? Because I believe that BS should not be one of the things that we teach our students. Because we should not continue to lionize bad explanations and even pseudo-science when we should know better.

On that note, if you notice any errors in my explanations, please let me know.

In part 1 of this article, we will look at reaction force (the most incorrect of Choi’s principles), concentration, equilibrium and breath control. Also check out part 2, where we will break down the issues with Choi’s thoughts on mass and speed (the most poorly explained principle).

Reaction force

Choi’s entire principle of reaction force is based on Newton’s third law, which basically says that if I exert a force on something, the other thing will exert an equal force in the opposite direction. To illustrate, Choi wrote, “When an automobile crashes into a wall with the force of 2,000 pounds, the wall will return a force of 2,000 pounds.” That much is correct.

He goes on to say, “if your opponent is rushing towards you at a high speed, by the slightest blow at his head, the force with which you strike his head would be that of his own onslaught plus that of your blow.” That’s not quite accurate. That’s not how force works. Your fist exerts a force on his head, but his head also exerts an equal and opposite force on your fist. A force doesn’t become greater just because the two objects are moving in opposite directions. What does change is kinetic energy. When two objects are hurtling toward one another, their kinetic energy is multiplied, not their force. That’s what makes the hit harder.

Choi’s next sentence is wrong by definition: “The two forces combined; his, which is large, and yours, which is small are quite impressive.” There are no large and small forces here. They’re equal. Energy and force are not the same thing.

So what? I’m splitting hairs about physics terms. Your punch is still harder when the guy is moving toward you, so the spirit of the point still stands, right? I just want to show that we’re only into the first “scientific” paragraph of the Theory of Power and the science is already dodgy.

The reaction hand

When I hear Taekwon-Do instructors talking about reaction force, they usually aren’t talking about someone running into your fist. Instead, they mean pulling your opposite hand back to your hip when performing a technique. As the theory goes, the “force” of your punch is made stronger by the “reaction force” of the opposite hand being pulled back to your hip.

This is also wrong (and definitely worse for a Taekwon-Do student than mixing up “force” with “energy”). You put power into your punch by accelerating your fist as quickly as you can and putting as much of your body weight into it as you can (while still keeping a stable position). Pulling your opposite fist back to your hip does none of these things.

Let’s use a standard TKD reverse punch as an example. Because you’re moving your fists in opposite directions but keeping your body square to the target, you may be robbing yourself of some power. Think about it: if your right hand is punching and your left hand is pulling backwards, your hands are trying to turn you counter-clockwise. Your hips have to compensate for this so you can stay full-facing to the target. You’re taking away some of your ability to put body weight into the target. Watch a boxer throw a reverse punch. Their body will twist, meaning they can get more extension on the punch, but can also put more weight behind it.

Even if pulling the fist back to the hip does somehow increase power when punching, what’s the point in doing it for, say, a downward block? If you would want the forces to be equal and opposite, wouldn’t it make sense for the reaction hand to move upward? That’s what we’re supposed to do for a pressing block with the palm, so why not a downward block? For that matter, why don’t we throw our hands forcefully in the opposite direction when kicking?

Going back to the boxing analogy, boxers don’t pull their hands back to their hips and I would say that, on average, they throw harder punches than we do. Not only does pulling your hand to your hip not add power, but it leaves you tremendously exposed to counterattack.

The purpose of pulling the hand back to the hip isn’t to add power to the punch itself. This is another case where General Choi and the other TKD pioneers likely heard bad information from their Karate instructors. That hand is actually grabbing someone by the wrist or clothing and pulling them in closer, either so you can guarantee you hit them or so your punch hits harder (see the whole part above about an opponent moving toward you). Don’t believe me? Watch this old Karate video to see the effectiveness of the grab-’n’-pull in action.


Unlike much of the Theory of Power, Choi’s thoughts on concentration seem pretty sound to me. They can be summarized as:

  • Use a small attacking or blocking tool to concentrate your energy into a small target area so you can cause the most damage.
  • Concentrate on tensing your muscles at the point of impact, not throughout the technique.
  • Concentrate and coordinate all your muscles toward the attacking or blocking tool: big muscles like those in the hips and abdomen move first, smaller muscles like those in the arm move last.

The first point is related to the concept of pressure. If a force is applied over a smaller area, the amount of pressure will increase. To see what I mean, slap yourself on the thigh with an open palm. Now make a fist and extend your middle knuckle, and hit yourself at the same speed. Notice which one hurts more?

The second point is the only one that could be a problem, but it’s standard practice in boxing and every other striking-based martial art that I’m aware of. Relax the technique to get speed, and tense just as you make impact. The faster you can throw your punch, the harder you can hit. However, note that the tension we apply when doing patterns (to stop the motion and prevent hyperextension of joints) is different than the tension we apply when hitting something (when the target stops the motion and prevents hyperextension).

The third point is also standard practice. Uncoil your body like a whip. If you want to get the most power possible in your punch, don’t just start from the hips; start from the feet. Grind your feet into the floor and move up through your legs, to your hips, to your abdomen, to your shoulders, to your arm. Your body should rotate as you go. A similar idea applies to kicking, but from the top down. Move your shoulders first, then your abdomen, your hips and finally your leg.


This principle also makes sense. To put power into your technique, you can’t be off balance. But I would prefer if this point were simply called “balance” and not “equilibrium.” Equilibrium, in this sense, means that an object is in a state of rest or uniform motion (in other words, it’s not accelerating). If you want to produce a powerful strike, you have to accelerate at least part of your body. It’s possible to stay in balance without being in equilibrium.

There are a couple of other things to note. First of all, I’m not quite sure what this means:

Equilibrium is classified into both dynamic and static stability. They are so closely inter-related that the maximum force can only be produced when the static stability is maintained through dynamic stability.

So I can only produce “maximum force” when I’m in balance while standing still because I’m also in balance while moving? That’s some quantum-physics level stuff right there. I’m sure there’s a valid explanation for it, and I could make a serious guess if I wanted to, but I wish Choi had just told us what he meant.

My other point of contention is this:

One additional point; the heel of the rear foot should never be off the ground at the point of impact. This is not only necessary for good balance but also to produce maximum power at the point of impact.

That’s not always true. For example, when a boxer throws a cross, the heel of the rear foot is supposed to be off the ground. Otherwise, the punch isn’t as effective.

Breath control

General Choi says that proper breath control does three things:

  • Gives you better stamina
  • Allows you to better take a shot
  • Allows you to put more power into a strike or block

The first two are definitely true. The third may be.

If you’re breathing effectively, you’ll be less prone to fatigue. That’s exercise 101 right there.

If you exhale sharply and tense your abdomen when taking a shot to the body, it hurts much less than it would otherwise. I know that from experience, and if you’ve ever tried it, I’m sure you do too. However, Choi says that a proper sharp exhale can stop a person from going unconscious. I really have my doubts about that. All the breathing techniques in the world won’t keep the lights on if you take a hard enough shot to the chin.

Finally, we come to adding power to a technique through breathing. This one’s debatable, but quite possibly true. In not only Taekwon-Do, but also in styles like boxing, Karate and Muay Thai, students are taught to exhale sharply when throwing a technique. Even in weightlifting, proper technique involves exhaling during the lifting phase. That exhalation may help produce more power. In TKD and Karate, the breath is meant to be cut off for a split second during the moment of impact, helping to tense the body. This tension helps lock all the parts of the body in place, which may also help produce more power. I know from experience that it’s much harder to throw a strong punch when holding my breath throughout the punch or inhaling.

On the other hand, maybe all that tension in the abdomen isn’t necessary. Boxers aren’t taught to tense quite like we are, and, again, they tend to punch harder than we do. Come to think of it, when was the last time you tensed your abdomen when throwing a technique in a sparring match?

General Choi also tells us to “never inhale when focusing a block or blow against an opponent” because it can slow your movement and reduce power. True, if you want to produce power in your technique, inhaling at the moment of impact is a bad idea. But as Karate expert Dr. Elmar Schmeisser points out, there are situations where inhaling during a technique is a good thing. Inhalation works well when you don’t need to put power into the technique; for example, if you want to parry an opponent’s strike and not block it forcefully. The benefit of inhaling is that it produces better combinations: you can launch your counterattack more quickly and fluidly, rather than using the staccato out-breath, out-breath rhythm of blocking and punching that we’re used to in our patterns.

To be continued…

In part 2 of this article, we dig into mass and speed, and talk about why all of this pedantry even matters.

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  • Jay Lee

    I have pro kickboxing competition experience, and have coached kickboxers as well. I’ve done a decent amount of Muay Thai, boxing, and MMA training as well. I also have trained Olympic weightlifting and other functional Crossfit-like movements. I don’t have much Taekwondo experience, but I’ve been watching my son do TKD and I have a lot of thoughts on it.

    1) Choi’s usage of “force” may be off, but the point about how devastating it can be to land a hard strike on someone charging in is spot on. It’s also very hard to do. In some sports, it requires a reasonably high level of experience — for example, you won’t see many beginner boxers who can punch off their back step, and nor will you see beginner kickboxers who can time a hard counter-knee to meet an oncoming puncher. However, in my observation, sports like Taekwondo (both styles) and Shotokan karate seem to develop that minute sense of timing a lot earlier on. I believe it’s due to their relatively large competition areas, and their emphasis on long-distance fighting.

    2) Regarding the reaction hand, I think it makes sense to pull it back. I look at poomsae primarily as an expression of good functional body mechanics, and secondarily as a performance art. Pulling the reaction hand back is simply good body mechanics. Not only does it aid in rotating the hips and shoulders, it also cues the shoulder blades to retract, which make them more stable and less prone to injury. Proper bench pressing, dips, and overhead lifts all require retracted shoulder blades to maximize stability and strength, and minimize risk of injury.

    3) I totally agree with you (and disagree with Choi) about the rear heel lifting off the ground. The most stable position for a leg that is behind you is to be on the toe, not the heel. When Olympic weightlifters do a split jerk and lift 2+ times their own body weight above their head, they will always raise the heel of their rear leg, which is testament to how stable this position is. I don’t think there has ever been a Oly lifter who has chosen to perform the split jerk with the rear heel down. Aside from stability, raising the heel is also necessary for rotational power. You can see boxers raise their heel for hip rotation when they throw a rear straight.
    Actually, lifting the rear leg altogether can give you more rotational power, but of course you will not have stability or the ability to recover stance. Sometimes when boxers get sloppy or are going for a KO, their rear leg may fly completely off the ground. And you can see javelin throwers and baseball pitchers (who don’t care about stability or defending a counter punch) completely whip their rear leg up to give their hips maximum rotational power at the end of their throw.

    4) On the breathing part, I strongly feel that exhaling is necessary for maximizing power. Olympic weightlifters, gymnasts, dancers, yoga practitioners, and many martial artists (judo, MMA, boxing, Taekwondo, kickboxers, etc) will have some breathing routine that involves exhaling somewhat before exerting power. This is the most intuitive way to cue the abdomen to get tight, which is an absolutely necessary step to maintain good hip, spine, and shoulder alignment under large physical strain. For light contact sparring rules, bracing the hips, shoulders, and spine might not be as important (although I imagine it is still necessary given the speed requirements), but for full contact rules it’s absolutely necessary. Not only do most strikes require a decent level of power, but bracing is necessary for speed (for example, closing the distance, slipping a punch, side stepping to avoid a strike, etc all require some bracing to maximize speed) as well as absorbing blows.

    • Thanks for the comment, Jay. Great insights.

      Lyoto Machida is an excellent example from MMA of someone who can get people to launch themselves onto his fist. By fighting at a long range, he gets people to commit to taking an extra step, and they end up doing half the work for him because the punch is harder.

      Good points about pulling the reaction hand back. I never thought about retracting the shoulder blades. That makes sense. And yes, the reaction hand can help rotate the hips and shoulders (which would add power and range to a punch), but in TKD we’re supposed to pull our reaction hand back without rotating the hips and shoulders. That seems odd to me.

      I completely agree with you on your other points as well.

  • Jay Lee

    By the way, you talked about boxing.

    I’ve actually spent a lot of time thinking about why punches in kickboxing, boxing, and MMA look so different from Taekwondo punches, whereas the kicks are fairly similar. Obviously there are still differences, but the body mechanics in the kicks are more or less the same, whereas the mechanics for punches are completely different.

    Here’s my theory. Without wrist support or knuckle cushioning, the types of punches that people assumed you could throw without risk of breaking your hands was very limited. It’s risky to aim at hard surfaces like the skull, punches need to land at precise angles, and the speed and power need to be controlled.

    The straight body punches in Kyokushin karate and WTF taekwondo both look similar to what you see in kata / poomsae. The body mechanics are basically the same as a bench press or a push-up; there is limited body rotation, shoulder blades are somewhat retracted, and the body more or less perpendicular to the direction of the punch. All of this makes the punch quite stable, but not necessarily that powerful or dynamic.

    On the other hand, punches in gloved sports are totally different. Punches are freely thrown at the head, the angles come from all different directions, and punches can be loaded with the full body weight behind them, or with the blinding speed and elasticity of a whip.

    The rear hand straight can be thrown with many variations, but there is usually a fairly large amount of hip and shoulder rotation, the shoulder blades rotate upwards and protract forward somewhat to lengthen the punch and continue its momentum, and the torso may be tilted forward for various reasons. All of these attributes make a boxer’s punch more like a pitcher’s throw, and not much like any freeweight lift. It gives the punch a lot of speed, power, and reach, but sacrifices stability — well worth the price given the rules of the sport.

    That being said, back to the comment on the reaction hand in poomsae, actually punches in gloved sports usually DO involve pulling the guard hand back, mainly to aid in shoulder rotation. Furthermore, in practice many times the guard hand does go down to the chest or waist. While we’re generally taught to keep the guard hand close to the face, in reality the best punchers in the world will allow their hand to stray down, especially when they’re going for the knock out.

    I watch a lot of boxing and kickboxing, and the vast majority of knockout punches are performed with the victor’s guard hand pulling back close to their waist. I just watched Conor McGregor vs Floyd Mayweather, and when Floyd finished Conor in Round 10, it looked like he was performing poomsae (not really, but hopefully you understand what I mean — his guard hand wasn’t anywhere near his chin). Even picture-perfect masters like Giorgio Petrosyan, who is about as close to textbook form as they come, pulls his guard hand way down to his waist whenever he tries to land his left hand with lots of power.

    • That’s a really interesting theory on the different punching styles. I had noticed that a lot of bareknuckle styles tend to throw more punches to the body because of less risk of damaging the hands, but you bring up some great reasons for why the techniques of those punches could have developed the way they did.

      I have to admit, not having done a ton of boxing or kickboxing, I didn’t really think about the reaction hand coming to the chest (or even waist) when throwing power shots. That’s a good point. I was really just thinking about “proper” form in boxing. Now that you mention it, I have seen people dropping their reaction hand to get more extension and rotation as they attempt knockout punches. It makes sense. But as I alluded to in my reply to your other comment, General Choi wanted us to pull the hand back to the waist for all punches, keep the shoulders and hips square, and generate lots of power. Seems to me like keeping the shoulders and hips square and generating lots of power kind of cancel each other out.

      Moving away from boxing, I know that Kyokushin karate fighters tend to pull their reaction hand back to the chest (you can really see it when you watch them pumping 1-2 punches). But they don’t have to worry as much about maintaining a high guard when punches to the head are illegal—the same reason World Taekwondo fighters keep their guards so low.

      • Jay Lee

        Right now there doesn’t exist any true bareknuckle styles where you can punch the face that I know of. Kyokushin is the main bareknuckled sport now that doesn’t use wraps or gloves, But they don’t allow punches to the head, which changes things a lot.

        Dambe (West African martial art) and Lethwei (Burmese boxing, similar to Muay Thai, except no gloves, headbutts are allowed, no referee decision) are full contact striking sports that don’t use gloves, but they do wrap their hands which prevents rampant hand breakage. Both of these sports use throwing mechanics for their punches — ie, lots of rotation and weight transfer, and some internal rotation of the shoulder and elbow to give the punch a long arc (and therefore greater reach, momentum, and speed). Thanks to the protection of wrist wraps, they do not use the “bench press” mechanics of karate and Taekwondo, which are less dynamic, more isometric and stable, and generally target soft areas like the nose or solar plexus.

        Bareknuckle boxing is more or less an extinct sport; there is a small league or two but they don’t have enough practitioners to be considered a refined sport. However, reading descriptions and looking at drawings of the sport, it appears they focused far more on hitting the body with hooks and uppercuts, and choosing to strike the head very selectively. They also used more wrestling and clinching. While I’ve never seen footage of how the punch mechanics worked, I think it’s safe to say that the speed, power, and variety of angles of the modern cross is far beyond what it was in the pure bareknuckle days.

        Aside from allowing punches to use “throwing” mechanics, another benefit of hand protection is that it allows the use of the high guard, and also use the guard hand (ie, the “reaction hand”) to defend counter strikes. This mostly stems from gloves; wrist wraps alone do not make these effective defenses. Without gloves, covering up behind a double forearm block, and “catching” punches (the main way the guard hand can defend counter punches) can work, but are far less effective. By and large, sports without gloves (including Dambe and Muay Boran, which had wrist wraps but no gloves) rely on forearm parries, sway-backs, or stepping backwards to defend punches to the head. Look up any “bareknuckle boxing” photo online and you’ll see the stance of old-school boxers looked like Shotokan karate-ka or fencers.

        MMA is an interesting case study, because while it has gloves and wrist support, the gloves are very small. Therefore, the high guard and catching punches is less effective than they would be with bigger gloves. Conor McGregor is a good example of someone who has virtually eliminated these defenses from his game. His hands are usually far from his face, he relies primarily on head movement to defend punches, and he rarely covers up with the double forearm guard.

        Finally, I’ve also thought about how hand protection changes the nature of injuries. Obviously they greatly reduce hand breakage — although even with gloves and wraps, boxers break their hands all the time when they hit the skull at a bad angle, or catch the pelvis when hitting the body. Gloves also greatly reduces cuts and permanent eye injuries, which are issues with ungloved sports, or sports that allow elbows (ie, Muay Thai). However, because you can hit the head a lot harder and a lot more times with gloves and/or wraps, I suspect that the risk of brain trauma has probably increased a lot with the advent of hand protection. Finally, just like baseball pitchers, rotator cuff injuries are very common among boxers (in fact, they are the most common injury alongside hand injuries). Aside from the overuse issue, the fact that they use throwing mechanics often means that boxers’ shoulders protract (ie, slide forward out of the stable shoulder position). Furthermore, some boxers choose to hunch their shoulders to hide their chin from strikes, which also tends to be accompanied by scapula protraction, internal rotation, and shoulder instability. Overall I think gloves and wraps make punching a much more exciting set of techniques to use and defend, but it’s also important to remember that it is sport specific, and might not be the best idea to apply all of the modern boxing techniques to situations that have different types of hand protection, including MMA (smaller gloves) or in self defense (no gloves, no wraps).

        (By the way, I personally don’t like hunching to hide the chin. Instead I teach to tilt the pelvis, just like Floyd Mayweather Jr. Tilting at the pelvis allows you to tilt your shoulders while maintaining reasonably good spinal alignment, and by elevating the lead it shoulder it also allows your chin to drop behind it without hunching. Floyd Jr is the master of the shoulder roll, and contrary to popular belief, he does not hunch his shoulders or internally rotate them).

        • I’m loving these comments! It’s absolutely true that most “bareknuckle” styles don’t even permit hand strikes to the head. Like you, I was also putting old-school bareknuckle boxing in that category, going way back to before boxing gloves existed. As you pointed out, they did strike to the head, but it was rare, even when they wrapped their hands. I had forgotten about lethwei. Interesting that they using the “throwing” mechanics. I wonder how much more frequently they get hand injuries.

          Also interesting that you brought up the risk of brain injury from boxing gloves. Your hunch is absolutely correct. Gloves aren’t meant to protect the brain, they were originally designed to protect fighters’ hands. And they do actually increase the risk of a brain injury. I’d recommend reading “Fight Like a Physicist” by Jason Thalken, if you haven’t yet. He covers all the science of it. I assume you’ve also heard that headgear amplifies the risk of brain injury even more—since the AIBA took away head gear for male athletes at the last Olympics.

  • rocket

    I fully agree with everything you write except one factual inaccuracy: Sine wave adds a step, namely a down motion. The precursor “Knee spring” was up-down. Sine wave is – down, up, down. Both are regardless misunderstanding of bodymechanics, but just wanted to point out that there is a distinct difference, not just exaggeration.

    • Thanks for your comment. I believe you’re right that knee spring is described as simply an up-down motion. But try to move up and down without bending your knees first (the first “down”). In knee spring, this “down” motion is extremely subtle. So subtle that it wasn’t even mentioned—maybe not even considered. In sine wave, the first “down” motion is bigger, and noticeable. Because the first “down” is emphasized in sine wave, some people misinterpreted it, and do the down motion too late, which means they do a double sine wave. See this article for a more in-depth discussion:

  • Vasilis1996

    Good evening
    I would like to make a statement, on the part of the reaction of the hand and on the balance.
    The point at which the hand is pulled to the hips may have some basis. When jerk the hand to the hip, maybe it transfers kinetic energy to the body (to the opposite shoulder as uncoil whip), which may help make the punch stronger.
    Secondly, a paragraph that states that the whole foot must be to the ground and not on the ball of the foot (such as boxers), maybe, refers at the moment, when we are kicking. Because, with the whole foot stands to the ground, it has a larger surface than ball of the foot.
    Thank you very much for your attention and sorry about my writing.