Reply to applied force vs visible force in TMA/MMA [Updated and Edited]

Martial arts principle and technique analysis

This is my reply:

The first video’s kick imparts much more kinetic force, but most of it is lost due to two points.

1. The human body bends and automatically moves away from strong stimuli or pain in order to prevent damage to the body. Thus the body’s automatic balancing system will take steps back when a strong force comes from the front, rather than just stand in place and then fall backwards like a fallen tree and then have the skull crushed as it hits the ground. People who’ve been basically knocked unconscious, that’s basically how they fall. The other ones that lose some consciousness or just awareness (got dizzy), tend to lose strength in their legs first (a result of hitting the jugular on the side of the neck as well) and then they just fall vertically down then horizontal. But the ones that get knocked out while on their feet, they just go with the force and fall like a log.

2. The second is I think the more important point as it is something that can be controlled for. The first point is harder to control for with respect to the requirement that you literally have to do artificial things like put someone against a wall, make him prone on the floor, or place your foot behind his foot so he can’t back away without falling into the gravity well head first, to ensure a person’s body doesn’t move away from the impact. The second point is force reflection, a concept I describe as the attacker’s ability to reflect, not absorb, the force that comes from striking a target. A strong stance is designed so that a heavy force strike will not reflect into the attacker, but everything goes into the person. Thus fist breaks concrete and the force breaks the concrete. But it would have gone into the fist if the concrete had not broken. Force follows the way of least resistance and does damage to the weaker material. Because they are kicking someone, a lot of the force is going into the human leg joints and some of it is being reflected, but much of it isn’t. Thus without correct body structure, force will not all go into the target and much of it is wasted being re-absorbed into the attacker’s body.

Duration is an important concept in improving the ability to make a strike’s kinetic force do work on the target. Often the duration of contact is not long enough. To prevent the target from dissipating the kinetic force, one must maintain contact and continue accelerating into the target area. See Point One above. The kinetic force will “push”, as you describe it, the target away, but the constant contact and acceleration will penetrate through the body tissues’ natural ability to dissipate/absorb force, exceeding its tissue connective limitations and generating injury. Or just a huge bruise and damage on the muscles if the targeting was off.

Continuing on, the total amount of force in the push kick is much greater than the shocking kick, but the greater force is not applied correctly or efficiently. The same applies in hand strikes or any strike, including joint manipulation and throws. To snap a joint, one must isolate the joint and tightly hold the lever, and then apply the force and make sure you don’t let go until the joint is destroyed. In a throw, one must obviously not lose contact with the opponent’s body too soon. An application of a principle, based off a theory, applies to one technique’s situation, but principles are the underlying engine of all applications. Thus a single principle can be applied the duration of a hand strike, a foot strike, a joint break, or a body throw. Efficiency is something that affects all of them. Efficiency will improve the performance of all of these “strikes” (yes I call all of them strikes, more or less).

To address a different subordinate subject: concerning the shock kick, what I see is a lesser concentration of kinetic force in a smaller area. The kick doesn’t extend as far as the first kick, but that means when it has contact with the target, it keeps on going using the muscle extension. That’s not nearly as powerful, objectively, as a full extension or body weight powered strike, but the duration is long enough to penetrate the force into the body. If, however, you increased the total kinetic force of the shock kick to the same as the push kick, yet retained the shock kick’s duration of contact and penetrating ability (what I would call acceleration while transfering force to target area), then the target human would still fly back. Except he would now be horribly injured in the process as he flies back. The tissues would exceed their absorption and resistance limitations and break. Bones would snap. The tissues in organs would erupt internally, leading to internal bleeding and dysfunctional organs. Depending on the target, different types of such injuries can result depending on what the kinetic force destroyed in the body. Thus the important point is not total power, but how much kinetic force can be transfered into the target area without the target absorbing/reflecting the force and without your body re-absorbing and reflecting the force of your own strike.

Alternatively, another vital part is the targeting: where it is and how large the target one is hitting. The smaller the target area, the more force is applied to the target. The larger the area, the easier it is to hit, but concurrently less effective the kinetic force becomes. Theoretically, you don’t need a huge kinetic force if you can decrease the surface area you are applying the force to. A needle doesn’t need to be Spin Kicked into a person’s arm, for example, to penetrate the skin. But you’d need some kind of car crash to penetrate your elbow through a human body. Probably not going to be good for your elbow or the unfortunate person that gets hit by your elbow.

Duration is an important aspect or application of a common principle. To apply kinetic force, one must keep that force accelerating into the target and not simply let the target move away and dissipate the force using distance/time. Human muscles can only accelerate at maximum for certain lengths of extension and timings. But the human body, aided by a gravity well, has a constant acceleration: 9.8 meters per second, per second. Or, alternatively, the human body in motion has a huge mass in motion. No muscle can continuously apply that kind of acceleration, but gravity can and will when the body is in motion. No muscle has as much mass as your full weight, so when you hit someone with your arm’s mass it is not going to be the same as hitting someone with your weight of 100-200 pounds. It’s unlikely your punching hand weighs 100 pounds.

It’s a bit of a vector calculation, since gravity is pulling you down but you’re moving horizontal, 90 degrees, to the pull of gravity. Basic physics calculates this as being partially increasing the speed of forward momentum due to gravity. Any extra that can be used to break through a target’s resistance or absorption ability, will be productive force spent well. Any extra is good, one doesn’t need a “precise” math formula to use it well. It’s good enough that one can “grasp” the concept that vertical and horizontal momentums can feed into one single strike and add to each other.

Commenting on Dan’s use of the “shock kick” to strike different targets: the kicks I was trained to do only targeted the lower body, not anything above the navel, and the solar plexus was definitely out. So were the kidneys in the back, if the target human is facing away from you. The foot to the back of the knee, that was a classic we trained in as well, but we would place most of our weight into it (in order to crush the kneecap using an application of downward force or simply dislocate the kneecap as it tries to bend but the foot is prying the knee joint itself apart and preventing it from bending correctly. We’re basically shifting into a forward stance, like a cat, with that. Or even a horse stance sideways. The point is that once the body is in motion, striking is now much more effective on human body tissue, regardless of whether it is kicking or hand attacks. Even if he moves his leg out of the way, I’ve simply fallen into a perfectly normal stance and if he is close enough, my upper body will also strike downwards as I am falling into the stance, thus making use of my kinetic force, rather than wasting it by recovering from the ground up.

The targets in your kicking video, were mostly accessed by hand strikes of that nature in my training. Balance was an important criteria, but it was more because it followed straight line projections of force application. A kick can’t go in a straight line and apply force, when the distance is too close or far, or if the body is turned one way vs another. Regularly or optimally, the lower body then gets struck by a kick stomping down and the upper body is accessible by the accelerated body powered strikes of the hand, forearm, elbow.

A body powered strike is usually seen in Taji Quan or other internal kung fu. They practice very strong stances that can resist and reflect a lot of force going in any direction. That is very useful when one’s attack power is so high when applying it to a target that it’ll actually bend your body if you lack the proper structure. This is an example of an attacker’s body re-absorbing their own force: see Number Two above. This is something that is bad. You do not want to re-absorb the force of your own blow because that means your target is getting less force applied to it. High kinetic force is of no use if one cannot force it into the target area with reflection and constant acceleration: penetration. Body tissues tend to dissipate and absorb force automatically, since a lot of it is water, true. Everything has a limit, however. Stack all the odds in your favor. Reduce the opponent’s ability to absorb or reflect the force of your strikes and eliminate your body’s tendency to re-absorb the power of your strikes.

So in retrospect, it is impressive that the guy that came to watch your dojo/training kicked the bag and it went flying up. However, unless his leg is stuck to the bag as it goes flying up, and constantly applying and accelerating the force into the bag to exceed the bag’s resistance potential, he is doing no damage to the bag and no injury to a human. The human body can take a lot of non-specific trauma without going down. It cannot take injury however and remain 100% functional.

Looking over a couple of TMAs for the past few years, I have noticed that the kind of high level skill required to increase the very tip-speed of your hands or foot to make a strike apply more kinetic energy is often the realm of “external martial arts” based upon strength, speed, conditioning, and physical ability. While the internal martial arts depends a lot more on internal structure, transitioning of kinetic force using the whole body, which includes transitioning force downwards by going from a high stance to a low stance. To that extent, I suppose the training methodology I undertook is closer to internal martial arts than external martial arts, although it was never called any of that to begin with. It took me awhile to understand why external type strikes didn’t look the same to me, when internal style movements looked almost the same as my own.

P.S.http://dandjurdjevic.blogspot.com/2008/09/hitting-harder-physics-made-easy.html

Is also a good resource on this matter. I’ve read Dan Djurdjevic’s blog recently over the past few days and he has a very good and accurate grasp on the subject matter. A few of my contacts at Yahoo!Answers (Martial Arts) concurs. I write and comment on his blog entries not because there’s much I find wrong, but simply because I enjoy the analysis of principles and techniques.

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4 Comments on “Reply to applied force vs visible force in TMA/MMA [Updated and Edited]”


  1. Very insightful analysis Ymar. You have clearly considered the physics of martial arts at some length (as few have) and you are to be commended.

  2. ymarsakar Says:

    Most of this work was done by Torin Hill and Chris RB of Target Focus Training. I simply took the principles of the physics of the human body in motion and applied it to a few things they didn’t or never focused on.

    As Newton said, if he had gone as far as he had, it was because he stood upon the shoulders of giants.

  3. Torin Hill Says:

    Point 2, can be accurately defined by the concept of Collision (http://en.wikipedia.org/wiki/Collision).

    Additionally, the Impulse (http://en.wikipedia.org/wiki/Impulse_%28physics%29) will help define the idea of Duration for you.

    Thanks for the credit, but I am not “of Target Focus Training.” Haven’t been for over 5 years. 🙂

  4. ymarsakar Says:

    Thanks for visiting and commenting, Torin.


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