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Kenpo / Kempo - Technical Discussion A non-political forum for the discussion of the techniques and forms of Kempo (Kosho Ryu, Ryukyu), Kenpo, American Kenpo and Kajukenbo. Please keep all discussion here on topic, polite and professional.

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  #1  
Old 09-07-2003, 06:28 AM
Kenpomachine
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Wrist alignment in punches

Working on the bag the other day I noticed that my wrist alignment, while being correct for vertical punches, was not for regular front punches . I mean, the contact surface was smaller for the horizontal punches than for the verticals.

Am I doing something wrong? Because changing the wrist alignment for the horizontal punches I don't feel as confident of the power I can transfer to the target. The wrist position feels more forced and weak.

I'll appreciate your comments on this, gentlemen.
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  #2  
Old 09-07-2003, 09:46 AM
pknox
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It actually makes perfect sense that it would be easier to align the wrist in a vertical punch, if you think about biomechanics. When you punch a target, force is distributed throughout your body - but the areas that take the brunt of the force are the hand, wrist, forearm, and shoulder. When you make a classic reverse punch (fist parallel to the floor), the two bones in your forearm, the radius and ulna, actually twist. This puts these bones at a bit of a risk. The way your body compensates biomechanically is by dispersing more force to the wrist, and less to the forearm - that way there is less of a risk of breakage of the two forearm bones. By contrast, when you make a vertical fist, the forearm bones are not twisted, but are still in their natural position. The force is then distributed evenly across the wrist and forearm bones. Interestingly, the force to the shoulder or hand doesn't really change in either case.

One tip I learned about keeping your wrist straight is to think of the fist and elbow making a straight line. Even when you're punching down on a target (say hitting someone in the face while you have them mounted) your elbow should not be above your wrist. Now, I know that because those two joints are actually connected by the forearm, which can't move, it is technically impossible to get your elbow above (or below) your wrist - but for some reason, thinking of that straight line tended to help me.

Did you actually feel the wrist move? If so, was it up and down or side to side?
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Old 09-07-2003, 12:42 PM
WhiteTiger
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Forearm structure

The forearm is unique in its structure in that the two bones, the radial and ulna, change relative position as your thumb rotates in relation to your elbow joint. Between the two bones is a web of tendons which limit their seperation. When the forearm is rotated to its limit one way the bones overlap bracing eachother forming essentially a triangle or truss which is exstreamly good at distributing force. When the forearm is rotated to its limit the other way the bones are essentially parallel and the web of tendons is drawn tight. This forms an eye beam like structure which is resistant to compression and torsion forces. But if your forearm is between these two limits, you have two seperate unconnected, unsupported bones which can slip, flex, or break.
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Old 09-07-2003, 12:50 PM
pknox
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Re: Forearm structure

Quote:
Originally posted by WhiteTiger
When the forearm is rotated to its limit one way the bones overlap bracing eachother forming essentially a triangle or truss which is exstreamly good at distributing force. When the forearm is rotated to its limit the other way the bones are essentially parallel and the web of tendons is drawn tight. This forms an eye beam like structure which is resistant to compression and torsion forces. But if your forearm is between these two limits, you have two seperate unconnected, unsupported bones which can slip, flex, or break.
Interesting. Does this actually say that when your wrist is at it's most extreme ranges of motion (completely pronated and supinated) the forearm bone/tendon combination is stronger? I was always taught that the forearm is so good at handling force because it distributes the shock and potential trauma so well among the other components (wrist/hand/elbow), and this is at least partially due to its rather unique bone/tendon structure. Shouldn't a bone be most likely to break when it's at its highest moment of stress and torsion?
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Old 09-07-2003, 01:11 PM
WhiteTiger
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Re: Re: Forearm structure

Quote:
Originally posted by pknox
Interesting. Does this actually say that when your wrist is at it's most extreme ranges of motion (completely pronated and supinated) the forearm bone/tendon combination is stronger? I was always taught that the forearm is so good at handling force because it distributes the shock and potential trauma so well among the other components (wrist/hand/elbow), and this is at least partially due to its rather unique bone/tendon structure. Shouldn't a bone be most likely to break when it's at its highest moment of stress and torsion?
I am not sure what your getting at, yes the forearm distributes force to other parts of the arm and body, it is able to do so by virtue of the structure formed by the bones and tendons while exibiting correct punching form. The bones are not under any torsion loads in these positions, unless by an outside force.
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  #6  
Old 09-07-2003, 03:18 PM
Kenpomachine
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Quote:
Originally posted by pknox
Did you actually feel the wrist move? If so, was it up and down or side to side?
Yes PK, the wrist moves to the side. But what doesn't move is the forearm, thus the feeling of broken alignment.

I also noticed that when beginning as in a vertical punch and rotating the wrist in the last moment the alignment doesn't feel so bad.

By the way, I think that when the line/alignment is broken, all the tension goes to the wrist bones and tendons, working with compression force, so it doesn't transfer to the forearm. Thus the wrist is more prone to suffer and get injured.

Thank you both for your input.
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  #7  
Old 09-07-2003, 03:34 PM
pknox
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Re: Re: Re: Forearm structure

Quote:
Originally posted by WhiteTiger
I am not sure what your getting at, yes the forearm distributes force to other parts of the arm and body, it is able to do so by virtue of the structure formed by the bones and tendons while exibiting correct punching form. The bones are not under any torsion loads in these positions, unless by an outside force.
OK. That makes sense then and you are completely right. The tendons pulling the bones together prevent torsion, and I guess acts like an absorber to handle the force of the punch, which (with correct form) is introduced at the point of the two knuckles that are the heads of the bones. Kinda like wrapping something in foam to prevent it from being hurt during shipping.

That's what I get for trying to understand biomechanics while still hung over.
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