17 July 2010

Impact and Momentum Techniques

In a previous post ("ITF Taekwon-Do: From Hard Style Karate to Soft Style Tai Chi") I mentioned that I think ITF Taekwon-Do has more in common with a soft style, as far as power generation is concerned, than a hard style like Shotokan Karate. I explained that ITF Taekwon-Do has evolved into using similar mechanics employed in "fa jin," employed by soft style martial arts.

In the video below, Glen Levy explains "fa jin" as impact oriented techniques, rather than momentum oriented techniques. He mentions hard style martial arts that uses linear style attacks and names Karate as an example of such a hard style that uses momentum oriented techniques. He also names Taekwon-Do as another hard style example. For most Taekwon-Do styles this would be a fair assessment. However, ITF Taekwon-Do has evolved much since its days as merely Korean Karate. It is my conviction that modern ITF Taekwon-Do, when adhering to its inherent principles, is not a 100% hard style -- like Japanese Karate -- any more, and that when Levy describes the fa jin principle, that is in fact how modern ITF Taekwon-Do performs its techniques -- even its longer, pulling-back techniques. ITF Taekwon-Do uses kinetic chaining where one muscle groups contributes to the force of the next muscle group, it requires the practitioner to "explode" from a relaxed posture, almost like "a sneeze", and then it requires complete relaxation -- a "sinking feeling" -- after the technique has reached its target

While I am convinced that ITF Taekwon-Do is not a 100% hard style any more, I am also convinced that its far from being a 100% soft style. The transition is still in progress and I doubt a full conversion from complete hard style to complete soft style will ever occur. Rather, I believe that ITF Taekwon-Do is attempting a balance somewhere between hard and soft style principles.

For this reason, what we see is actually a big number of techniques that are performed as impact techniques and a big number that are momentum techniques, to use Glen Levy's description. A reverse turning kick, for instance, is a momentum kick, while a normal turning kick is an impact kick.

What I'm finding personally exciting is trying to figure out which techniques function better with impact, and which better with momentum.It may even be possible that one technique could function best as either an impact technique or a momentum technique depending on the circumstances.


Stuart said...

Glen's interpretation of the physics involved is badly flawed.
Energy is a measure of work capability, it is not a magic cloud.
Impact is instantaneous, relaxing immediately after the strike may have many benefits, but trapping the impact energy in the target is not one of them. There is only ever speed and weight, and every type of strike from a pushing teep to a fajin punch is a balance/compromise between the two.
Everything that happens after impact is exactly that: something that happens after impact. This "bouncing energy" thinking is a very common error in martial arts physics (both Teri Tom, who wrote an excellent book on the straight lead, and Dan Djurdjevic have been guilty).
Times arrow flies in only one direction, you can't suck impact back out of a collision by being stiff, you can't add impact by removing your hand from the target more quickly (another related idea I have come across once or twice).

Everything reduces beautifully to speed/weight (weight also being a function of structure) on impact, and keeping to these parameters has been an enormous help to me in my understanding.

So then the true value of what Glen is describing has to be an aspect of either weight/structure, or speed, or both.
To me it seems fairly obvious that the "sneezing" aspect is employing sudden muscular contraction across the whole body in a very cohesive fashion, so speed is gained, and of course his structure delivers the weight.
The sudden relaxation has many obvious benefits; from a relaxed position you can strike again immediately , a relaxed arm wont pivot the body if a punch is deflected, you wont be unbalanced by subsequent pushing after the the collision, and not least of all - you are not wasting energy after the job is done.

SooShimKwan said...

Hi Stuart,

Thanks for this. Yes, I'm also quite happy with F=M.a

That has always been for me one of the great attractions to ITF TKD. Even though the ITF Encyclopaedia does make reference to such Oriental concepts like Ki, it is not foundational to the style -- it all comes down to simple Newtonian physics.