A list of the primary parts of the body used in a punch, from the beginning to the end of the punching motion, is as follows: fist, wrist, forearm, elbow, upper arm, shoulder, torso, hip, upper leg, knee, lower leg, ankle, and foot. This sequence of bones and joints I similar to the three-sectioned staff used in some martial arts.
Lay a three-sectioned staff on the floor and try to move end “A” of the staff along the floor make it strike an object. If you push the staff from end “B,” it will bend at the two joints and make it difficult to strike the object with end “A” with any force. If you push end “A’ toward the object, you will be easily be able to strike the object with some amount of force. However, if, while pushing end “A’ toward the object, you also push end “B” toward the object, you will add more force to the strike since the additional force will be transferred through the aligned joints to the point of impact.
The same principle may be applied to the sequence of adding forces the force of a punch. If you start a punch by pushing some body part in the punching sequence of body parts toward the target, you will upset the punching action and lessening the impact force of the punch. Power is lost because the additional applications of force by the different body parts are not applied in sequence, so they are not transferred efficiently through the next joint in the sequence. For a powerful punch, move the fist first, then the wrist, then let the forearm apply its additional force through the tensed wrist, then the elbow moves, then let the upper arm apply its additional force through the tensed elbow, etc. until finally, the foot pushes against the floor.
When punching, do not start the punch by first moving the elbow or shoulder, or any other body part. Move the fist toward the target and then sequentially apply all the other necessary body parts so the fist is accelerated toward the target at its maximum speed and power.
Moving the fist first has another benefit; it helps prevent telegraphing the punch. If the fist moves first and moves directly at the opponent, the opponent will see a fist that appears to be getting larger. The eye detects movement quicker than it detects changes in size. This gives you a split second advantage before the opponent detects and reacts to the punch. A preliminary movement by the elbow, shoulder, or any other body part will warn the opponent of an attack. In addition, if the fist moves in a direction other than directly at the opponent, the movement will be detected quicker than a direct movement. Winging a punch give the opponent more time to react and evade or block the attack.
Of course, this means that you do not cock a punch. The punch just fires directly at the target from its present position. The punching action is similar to a jack-in-the-box toy; crank the toy, you hear the music, but you do not know then jack will pop up. When fighting, the opponent knows a punch will be coming at some point, but when it does, it should be a complete surprise.
For the maximum power of a punch to be transferred to the target, the arm must be aligned properly. Try this experiment. Have a partner perform a basic middle punch at your midsection and hold it there. Then put your hands around the puncher's shoulders and pull the puncher's fist into your abdomen. Usually the person's elbow will bend outward and start to collapse. This means the elbow was positioned in a way that all the power of a punch may not have been transmitted into the target, but instead, some of it was absorbed by the weak elbow. Usually this is because the elbow was pointing outward to the side. If the elbow is rotated slightly downward, the arm is much stronger.
At first, it feels unnatural to stop the elbow in this position; however, with practice it will feel more natural. To position the elbow this way in a punch, execute a vertical punch and then rotate your fist into a traditional punch position being careful to keep you elbow in place. Now try the above experiment with the elbow rotated downward. It does not bend as it did in the first experiment.
Besides more power, this elbow position has a secondary advantage. It protects the elbow from an attack from the side that may hyperextend it.