Master Stoker,
I would find it appropriate to answer your questions in reverse order.
Preliminary to the punch, the student learns proper stance, balance, body alignment and movement. They learn how to breathe correctly, and how to Kihap to control their breath, tighten muscles, and use Ki.
As for the punch itself, I first teach them the proper method of clenching the fist. I show them the bone alignment in the wrist and hand, and to use the first two base knuckles (index and middle finger) upon impact. I then show them the basic movements of the punch in slow motion - - the path the fist takes to the fully extended position. I teach them accuracy, and how to relax, then tighten the muscles at the proper moment. I'm not going to reveal all the secrets of a proper Taekwondo punch here (those who are trained will know what I am leaving out, and will hopefully understand why), but the power is equally generated throughout the entire body.
Yes, this is not the analogy I use, but it is a good one. Of course, there are many muscles involved in the extending of the arm in a punch, not only in the arm itself, but in the whole body. If you were to use only the triceps, the elbow would not move, and the arm would extend downward. The biceps muscle must relax to not resist the extension, and can be considered the brake, but only applied if you are not hitting a target, using light or controlled power, or only after passing through the boards when breaking. The elbow must come to a full extension, completely straight (not hyper-extended, but not bent), however, contact is made while the elbow is bent, and the fist only partly rotated.
This will depend on the purpose of the strike. Most initial strikes in self defense are stinging blows designed to be quick (not telegraph), daze or distract the opponent, and set up for the more powerful punch. Some people will want a clear definition as to what the term "target" means. It could be the surface of the object you are striking, a point just at the back side of the object, or the point at which you intend to stop your punch some distance beyond the object (more like your "target destination").
In my terminology, the target is the surface of the object you are striking. If it is your intention to distract your opponent, a snappy punch, or jab to the surface might only touch the skin. If you intend to stun, daze, or slightly injure your opponent, the full extension of your punch will be aimed an inch or two beyond the surface (into the middle of the object). If you are attempting to destroy the object, your punch is aimed, and your mental focus is to a point approximately one foot beyond the back of the target.
Thus, if you wish to break boards, you don't even think about there being a "target" there. I am going to rapidly accelerate my punch from point "A" (near my body) to point "B," and anything that gets in the way is going to be destroyed. If it just so happens that a few boards, or a person's body is in the path of my fist, then my fist will pass through it on the way to it's destination. The only "targeting" I do then, is the "bullseye" target of a pinpoint accurate point of entry into the front of the object, and exit out the back, with not regard for stopping until I reach point "B."
CM D.J. Eisenhart
