Why Do We Kick Like We Do?

[Why_Worry]

There's no right way to kick and no wrong way.

But also, assuming you're talking about the snap of the kick. The snap is realyl important because it releases your chi. Also for example, if you hit someone witha towel, it doesnt hurt if you just let it go straight, only when you snap it back does it hurt.

[DokterVet]

There's no right way to kick and no wrong way.

What are you basing "there is no wrong way to kick" on? Is any method of kicking correct even if it is entirely ineffectual? If this is the case, why do most instructors teach specific technique for kicking? If every way of kicking was right, then shouldn't the instructor just say "kick however you want"?

Also for example, if you hit someone witha towel, it doesnt hurt if you just let it go straight, only when you snap it back does it hurt.

A towel acts as a whip when used in the latter example. This article explains the science of a whip. http://www.hypography.com/article.cfm?id=32479.

As you can see, the whip is designed to accelerate a loop along itself. The whip is tapered so by the time the loop reaches the end it is travelling at over the speed of sound.

A leg is not a flexible tapered rope. It is a heavy mass with a hinge-like joint at the knee and one other at the ankle. It is not possible for it to behave like a whip.

[Hobbes]

Unfortunately, the human body does not work in the same manner as a towel. I have a very long winded physical/mechanical description of why these whip/snap/whatever puches and kicks do not aquire much power, but that's the subject of an article I was thinking of writing (upon suggestion).

The principles of the whip (ie the towel) does occur in karate. Techniques are classified as "push" or "throw". A front snap kick is a throw techique, utilizing the summation of forces or large (shortened) masses (levers) rotating around a central point (generally the hip region), when this motion is halted the forces are conserved (conservation of angular momentum) in the smaller lighter segments of the lever producing a much higher velocity. The damage of the weapon is determined by the over all mass of the moving object, its velocity and the contacting surface area.

Basic biomechanics 101

If you like I can supply some excellent references that explains these principles in as much detail as you like.

[Hobbes]

What are you basing "there is no wrong way to kick" on? Is any method of kicking correct even if it is entirely ineffectual? If this is the case, why do most instructors teach specific technique for kicking? If every way of kicking was right, then shouldn't the instructor just say "kick however you want"?

Context must be considered. Why don't we have only one type of battle tank? There must be a balance between many many factors. Cost, serviceability, appropriateness for the deployment, weapons of the enemy, ease of use, survivability, speed, range, armaments... etc... etc..

The context of a situation may call for a different kick, but there is a trade off. Speed, body position, overall power delivery, physical obstacles, ground surface type, and so on. Context determines tactics and strategy which influences technique, all for the purpose of exploiting an opportunity or a weakness in your opponent(s). Try doing a round kick in a very narrow hallway.

Also for example, if you hit someone witha towel, it doesnt hurt if you just let it go straight, only when you snap it back does it hurt.

When you pull back the towel, you are accelerating the tip of the towel. If you wet the tip of the towel, you are changing the shape of the towel but more importantly increasing its mass giving it more of an impact.

A towel acts as a whip when used in the latter example. This article explains the science of a whip. http://www.hypography.com/article.cfm?id=32479.

As you can see, the whip is designed to accelerate a loop along itself. The whip is tapered so by the time the loop reaches the end it is travelling at over the speed of sound.

A leg is not a flexible tapered rope. It is a heavy mass with a hinge-like joint at the knee and one other at the ankle. It is not possible for it to behave like a whip.

Ok... wow, where to start...

This isn't actually correct. The relative mass of the individual segments of the thigh, lower leg are different and it behaves much like a whip in the sense that the angular momentum of the thigh is conserved in the lower leg causing it to accelerate. True there isn't a curved section as in the whip ( which can be visualized as thousands of segments.)

If I make a chain with each link being of slightly less overall mass, I can accelerate that chain until the forces exceed the strength of one or more of the smaller segments and the steel will literally fracture violently into many small fragments due to the massive forces.

If I were to calculate the mass of your upper leg and then the mass of your lower leg and add an ankle weight to equalize the two, how fast do you think you can kick. (front kick that is).

The whipping action is not the only thing that is at work here... we have the forceful contraction of the quadriceps muscle group. We thus have the conservation of angular momentum, and the summation of forces working together.

Think of it like this: a motor car has X horsepower with X torque (foot pounds) The transmission is geared to have high torque and low speed at lower gears but as the transmission gears up, it can accelerate the car. there is a trade off between pulling power and torque.

Similarly we have short powerful muscles with relatively slow endpoint velocities which accelerates the mass of the entire leg, and smaller less powerful muscles which continue to accelerate the mass, this combined with the reduction in mass of the smaller segments result in a high endpoint velocity. In a kick the flexors of the leg are also the primary extensors of the knee albeit not all the hip flexors are involved. The forces generated by this group differs at different points during extension for a number of reasons, mechanical and physiological.

We chamber the leg so that the mass is reconfigured to allow us to accelerate the entire mass of the leg to a higher velocity around the hip joint. By shortening the lever (the upper and lower leg) it takes less effort to achieve this initial acceleration. I'm not going to get into the thrusting motion of the hips right here, but suffice it to say we want to have as much mass attached to that fast moving object (foot or shin) as possible to increase penetration.

[Hitman]

I have to jump in on this one and start another mess. I believe the effectiveness we see in ANY tourny is a direct result of the rules of that particular tourny. Tae Kwon Do kicks are effective in tournies PARTLY because they do not allow hand strikes above the throat level (at least not in Olympic style events.) They can go "all-out" with their high kicks. In the UFC, that style of fighting is effective PARTLY because of how those matches are set up. If all 12 (or however many there are) guys were to be throw into the ring at once, we would not see nearly so much grappling because 3 guys would gang up on the one guy rolling around wrestling to get a submission hold. In Muay Thai, we see a competitor going more "all-out" and throwing a LOT of his body into the kick- sometimes even dropping his hands to add more "umphh." In Karate style competetions, we do not see as much of this PARTLY because it opens you up to other techniques.

At least this is my opinion. Do you think it has any merit or am I way off base??

[powerof0ne]

In the camp of Muay Thai I'm under you're not supposed to throw your arm down as a counter balance while you kick once you get to a certain level...

I also know that in some camps they don't do this at all but I will say that I did do this for years. I still see many knockdown karateka stylists doing this "habbit"...

It's a habbit that will eventually slow you down when throwing a combination: jab cross*1 2*, rear leg head roundhouse...for instance the kick delivery would be very slow because of throwing your hand down after you throw the cross. It also telegraphs that you're throwing a roundhouse kick.

[Hitman]

Fair enough...so lemme ask you this then...what exactly is the difference between how your are taught to throw a kick and how Karate teaches you to kick??

[Hobbes]

In the camp of Muay Thai I'm under you're not supposed to throw your arm down as a counter balance while you kick once you get to a certain level...

I also know that in some camps they don't do this at all but I will say that I did do this for years. I still see many knockdown karateka stylists doing this "habbit"....

I have seen many different types of kicks done in a large variety of ways.

If we agree on the same outcome with the same set of criteria then the kicks will be more or less the same adjusting for height, flexiblity, speed and strenght regardless of system or style. I think some instructors do not fully appreciate the power they have with their students. The students look to the instructors as models of expert technique and I've seen whole generations of students emmulate an error for this reason. The instructor may simply have had an injury that prevents him/her from performing at 100%. These little mistakes then have explainations attached to them to explain some "hidden" technique, but in reality had absolutely nothing to do with the root cause.

kicking is pretty complex when you think about it and we don't have to fully understand the biomechanics to do it well. I remember being told by my a teacher I once had that " no amout of education or university degrees will change tradition ". Hmmm... wonder why I'm not training with him now? heh What I teach is a solid core of skills that can equip the student to branch off stylistically. I had a teacher who did this for me early in my training and I owe him just about everything despite the fact that we don't get along. I loved shotokan, but I didn't like the kibadachi and koduso-dachi in shotokan, yet shito-ryu favors neko-dachi and shiko-dachi respectively.(which I prefer) My knees love me for it.

Back to the habits. People tend to do what they find easiest or doing what they think is better. There may not be any "REAL" logic to this choice. Much like the guy who tells you that they don't eat processed food cuz its bad for you while sucking on a cigarette.

As an instructor: I don't want to teach something (which is risky to start with) and destroy someone's knees because of an uneccessary or potentially more dangerous than it needs to be. When I see a kick done differently from style to style, teacher to teacher, the first question that pops into my mind is "what is this person trying to accomplish, what is the context which this kick is being performed?".

[DokterVet]

What are you basing "there is no wrong way to kick" on? Is any method of kicking correct even if it is entirely ineffectual? If this is the case, why do most instructors teach specific technique for kicking? If every way of kicking was right, then shouldn't the instructor just say "kick however you want"?

Context must be considered. Why don't we have only one type of battle tank? There must be a balance between many many factors. Cost, serviceability, appropriateness for the deployment, weapons of the enemy, ease of use, survivability, speed, range, armaments... etc... etc..

The context of a situation may call for a different kick, but there is a trade off. Speed, body position, overall power delivery, physical obstacles, ground surface type, and so on. Context determines tactics and strategy which influences technique, all for the purpose of exploiting an opportunity or a weakness in your opponent(s). Try doing a round kick in a very narrow hallway.

While those are all good points to keep in mind when training, they in no way support the statement "There's no right way to kick and no wrong way" that I was questioning. They support an assertion that the most effective technique with which to kick depends on the circumstances. However, once again it in no way argues for the aforementioned statement.

Also for example, if you hit someone witha towel, it doesnt hurt if you just let it go straight, only when you snap it back does it hurt.

When you pull back the towel, you are accelerating the tip of the towel. If you wet the tip of the towel, you are changing the shape of the towel but more importantly increasing its mass giving it more of an impact.

A towel acts as a whip when used in the latter example. This article explains the science of a whip. http://www.hypography.com/article.cfm?id=32479.

As you can see, the whip is designed to accelerate a loop along itself. The whip is tapered so by the time the loop reaches the end it is travelling at over the speed of sound.

A leg is not a flexible tapered rope. It is a heavy mass with a hinge-like joint at the knee and one other at the ankle. It is not possible for it to behave like a whip.

Ok... wow, where to start...

This isn't actually correct. The relative mass of the individual segments of the thigh, lower leg are different and it behaves much like a whip in the sense that the angular momentum of the thigh is conserved in the lower leg causing it to accelerate. True there isn't a curved section as in the whip ( which can be visualized as thousands of segments.)

If I make a chain with each link being of slightly less overall mass, I can accelerate that chain until the forces exceed the strength of one or more of the smaller segments and the steel will literally fracture violently into many small fragments due to the massive forces.

If I were to calculate the mass of your upper leg and then the mass of your lower leg and add an ankle weight to equalize the two, how fast do you think you can kick. (front kick that is).

The whipping action is not the only thing that is at work here... we have the forceful contraction of the quadriceps muscle group. We thus have the conservation of angular momentum, and the summation of forces working together.

Think of it like this: a motor car has X horsepower with X torque (foot pounds) The transmission is geared to have high torque and low speed at lower gears but as the transmission gears up, it can accelerate the car. there is a trade off between pulling power and torque.

Similarly we have short powerful muscles with relatively slow endpoint velocities which accelerates the mass of the entire leg, and smaller less powerful muscles which continue to accelerate the mass, this combined with the reduction in mass of the smaller segments result in a high endpoint velocity. In a kick the flexors of the leg are also the primary extensors of the knee albeit not all the hip flexors are involved. The forces generated by this group differs at different points during extension for a number of reasons, mechanical and physiological.

We chamber the leg so that the mass is reconfigured to allow us to accelerate the entire mass of the leg to a higher velocity around the hip joint. By shortening the lever (the upper and lower leg) it takes less effort to achieve this initial acceleration. I'm not going to get into the thrusting motion of the hips right here, but suffice it to say we want to have as much mass attached to that fast moving object (foot or shin) as possible to increase penetration.

Interesting. I can see how the reduced mass of the lower parts of the leg results in a higher acceleration, but I'm not convinced that one should take that knowledge to conclude that he should kick like he would snap a towel (in other words I'm not convinced that this proves that a 'snap back' is a vital part of generating kicking power).

Snapping back with a towel creates the loop which eventually accelerates fast enough to cause damage, right? And this 'snapping back' is performed at the base end of the whip/towel (the equivalent of the hip joint).

Well when one 'snaps' a kick, the motion is normally initiated by a contraction of the hamstring which brings the leg back to the bent (chambered) position, followed by bringing the leg back to its original position using the momentum from the first motion. So the snapping is occuring at the knee joint, half-way through the leg, compared to at the source of the initial applied force in the case of the towel. So I don't see how that snap would have the same effect. In your own words, "when you pull back on the towel, you accelerate the tip of the towel." So unless you can pull back with your hips -- and I don't see how you could do that with much force due to the structure of the leg -- the motion won't result in the tip accelerating.

In summary: I stand corrected about a leg not acting like a whip at all, however, I still don't agree that the snapping motion of the whip technique applies to generating power in kicks.

[Hitman]

Quick question here...why are we talking about a whip? True that I don't particularly wanna get "cracked" with a whip, but I am not trying to bring up a welt with a kick nor tear through skin. I am trying to CRUSH whatever I am kicking, not "flick" it. Also, I don't believe there are near enough joints in the lower body to liken it to a whip anyway- I cannot flex the shin bone, nor the femur, etc. I thought the power in a whip was basicaly because the whip flexed continually while transferring kinetic energy into a continually smaller area (as the whip gets smaller near the business end). I may just be missing your point.

I think the physics behind a swing with a baseball bat may be more appropriate in this case.