Reinforced Block or Two Hand Block?

A common technique in Tang Soo Do, as well as other styles of karate, is something called Chun Kul Ssang Soo Mahk Ki.  This is loosely translated as two hand block in a front stance.  When I first learned this technique over 30 years ago, I was taught that it is a reinforced block rather than two separate blocks occurring simultaneously.

Two hand block - arms not touching
Two hand block – arms not touching
Two hand block - arms touching
Two hand block – arms touching

Many years later, the powers that be decided to teach it as a block with the two arms not touching, negating the reinforced concept.  There were still many in the Tang Soo Do community that taught it as a reinforced block, however.  I am sure there are many that still do.

I am not going to argue that one is right and the other is wrong.  In fact, I think there is a third option that seems more plausible.  More on that later though.

After years of science and engineering schooling, I couldn’t help seeing everyday things in terms of the physics behind them.  Since I spent a great deal of time training and teaching martial arts, I would think about the physics behind many of the things we do.

The two hand or reinforced block was one such technique.  The two hand block with the arms not touching is rather simple; it is just two blocks.  The reinforced block version with the arms touching is a different story.

Something never seemed right to me about the reinforced block.  Since the block originates from the hip and is executed in an inside to outside motion, it is logical to assume that the contact point of the block is the outside of the wrist.

Ready position
Two hand block chamber position
Two hand block final position

If you block with the outside of the wrist and reinforce it at the elbow, you are actually making the block weaker and less effective.  

We will assume that an effective block is one that stops the strike.  In that case, the net force will need to be zero,

Fnet = Fstrike + Fblock = 0

Let’s also assume that the center of rotation of the arm is equidistant from the wrist and to the elbow.

rwrist = relbow

If this is the case, a force at the wrist will result in an equal force at the elbow in the opposite direction.

Equal but opposite force occurs at the elbow

The same is true if you apply a force at the elbow.  There will be an equal force in the opposite direction at the wrist.  Reinforcing the block at the elbow will be the same as applying a force there.  You can see that this will take force away from the block, making it weaker.

Equal but opposite force occurs at the wrist when reinforcing at the elbow

In my opinion, if you truly wanted to reinforce a block using the outside of the wrist, it would be to reinforce on the inside of the wrist.  By doing this, you are applying a force in the exact opposite direction of the strike, thus helping the block. 

Alternate way of reinforcing a block – Bassai
Alternate way of reinforcing a block – Naihanchi
Reinforce block in exact opposite direction of strike

We have many examples of this type of movement in our forms such as Bassai and Nahainchi.

So, if the technique in question is not a reinforced block, what is it?  As I mentioned earlier, it could be two separate blocking techniques, one at the wrist and one to protect the solar plexus.  It seems a bit of a stretch and not very realistic to me.

What if the technique was not a block at all but a strike?  More specifically, a trapping motion with one hand and a strike with the other.  We see this type of strike in sparring occasionally.  It is certainly more prevalent in kung fu as well as Filipino martial arts.

An alternate theory of a two hand block’s purpose

So, you may be asking yourself, which is the correct interpretation?  The answer is…none of them and all of them.  We simply do not know.  The important thing is to have an open mind about the technique and to listen to all opinions.  You can then make an informed decision as to what seems like the best option to you.

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