Saturday, April 01, 2006

A step-by-step logical guide to improving a basic punch

In karate and taekwando, the forms/patterns/katas are routines with blocks, strikes and different stances. While they may be viewed as boring compared to exciting take-down techniques or sparring sessions, forms can be used as an invaluable teaching tool.

In all probability, the first form will involve the simplest of movements, with the punch and forward stance playing a major role.

For beginners, instructing on the stances is easy; how to execute a strike with forceful commitment is the tricky part. This essay will attempt to introduce a guide based on logical arguments that will arrive at a workable punch.

The forms will be used as the starting point, or axioms. One can even say that the forms will be accepted solely on the faith that years of development have refined it to its most practical incarnation.

The form (an excerpt):
The practitioner executes a block/strike and a forward stance, with the leading hand and leading foot on the same side of the body. The next movement is a step forward into another forward stance, with the other hand (now having become the leading hand due to the step) executing a punch.

A requirement of the form is that the step is finished the same time as the punch.



Argument 1:
The punch is designed to hit hard.
Therefore the fist is needs to move fast during impact.
In the form, the step and the punch is to be completed at the same time.
But the step is slow compared to the maximum speed of the punch.
Hence the practitioner should start stepping first, and start the punch near the end of the step such that the conclusion of these 2 motions coincide.


Argument 2:
The punch is designed to hit hard.
Therefore the fist is needs to move fast during impact.
To supplement the velocity provided by the extension of the shoulder and elbow, the shoulder itself should be propelled forward.
This can be done by rotating the upper body to push the shoulder forward, and also to lean the upper body forward in the direction of the punch.
Fist extension, body rotation and leaning must be performed simultaneous to ensure that the relative velocities add.


Argument 3:
The punch is designed to hit hard.
Therefore the fist needs to move fast during impact.
The extension of the fist relies on the upper arm rotating forward to drive the elbow up and forward, and the forearm rotating downwards to drive the wrist (and fist) forwards but not upwards (despite the elbow travelling with an upward velocity).
If the constraint of the elbow joint was ignored (the elbow can turn through 360 degrees as opposed to the real world where it only straightens to 180), at full extension of the fist, if the upper arm was still rotating, it will still bring the elbow upwards, but backwards. (The motion of the fist in the horizontal direction can be modelled as x = 2A sin (θ) where x is the horizontal distance from the shoulder, A is the lengths of the forearm and upper arm, and θ is the angle the forearm makes with the vertical. Refer to diagram.)
Therefore, maximum extension is achieved when the elbow is straight, but the fist’s velocity during maximum extension is zero.
Therefore, a punch that impacts during maximum extension is not a punch that hits hard.



Argument 4:
The practitioner does not wish to hurt oneself in the course of delivering a punch.
The elbow cannot turn more than 180 degrees (full extension)
At the instance maximum extension, if the upper arm is still being rotated by the muscles, and forearm is rotating downwards to keep the fist along a horizontal path, the elbow is moving upwards but not forwards not backward.
The elbow joint’s architecture forbids the elbow from travelling upwards because of the limitation of being only able to turn 180 degrees.
Any upward momentum of the limbs during full extension is dissipated via an impact within the elbow joint.
The elbow joint is not infinitely stiff.
Hence, there is an upper limit on the momentum that can be dissipated upon each impact to avoid damage.
Unfortunately, this upper limit is easily within reach of most people.
Thus to avoid injury, the practitioner must ensure that if the punch is not delivered to a target, the fist must be stopped before full extension by the action of muscle contraction instead of impact at the constraints of joints.


Argument 5:
The punch is designed to hit hard.
Therefore the fist is needs to move fast during impact.
The form is such that the previous step was a block/punch with the other arm extended, but this hand will be retracted to the side of the hip upon execution of the next punch.
Retraction of the returning arm will imply a net forward force acting on the upper body of the practitioner (a direct example of Newton’s statement that every action has a reaction).
This forward momentum can be directed towards the other hand that will execute the next punch.
Thus in addition to simultaneous extension of the fist, rotation of the upper body and forward leaning (as shown by argument 2), the previously extended hand should also be retracted at the same instance as the punching fist extends.


Proposition 6 (by Yuan Harng):
"Keep the greater parts of the body which do not contribute to the generation of momentum relatively loose. I found this to be of utmost importance in increasing the speed and strength of my movements."

The effect of this suggestion may not be obvious with the stepping foward stance punch, but it is very relavent for technically challenging moves. Do keep this bit of advice in mind when you are told you need to be 'less tense'.


This is not a complete guide but will hopefully help direct those in need of advice in the right direction.


End note:
Please do highlight any counter arguments, logical gaps or deviation from norm.





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2 Comments:

Blogger 小李飞刀 said...

hmm.. good guide, I would perhaps include an additional section on the need to keep the greater parts of the body which do not contribute to the generation of momentum relatively loose. I found this to be of utmost importance in increasing the speed and strength of my movements..

4:24 pm, April 01, 2006  
Blogger Lao Chen said...

Thanks.

5:11 pm, April 01, 2006  

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