IntroExtended punches are more powerful than bent arm punches.
ExplanationWhen lifting something, the further the arms are from the body the weaker they are, which is why it is difficult to lift a heavy object when the arms are outstretched. This is due to the increased torque required by the larger radius of rotation.
However, this does not translate to a linear punch since you are not lifting something. The more extended the arm is in a punch, the more difficult it is for the elbow to collapse, and the more force can be transferred into the target, which why people push heavy objects with their arms fully extended. An exception to this is when using an uppercut punch where the punching arm is bent because you are punching upward and essentially lifting the opponent with the punch.
If the intent of your punch is to push the opponent backward, keep the elbow bent and the arm close to the body to allow you to apply more pushing force, as with the one-inch punch. If the intent of your punch is to damage the opponent, whether the opponent moves backward or not, then punch with an extended arm.
ExamplesThis example uses a side thrust kick instead of a punch because the effects are more pronounced. However, an extended punch produces similar effects.
Watch people while they are kicking a body shield held by another person. If the kicking foot contacts the shield with a large bend in the knee, the result will be a pushing kick. The foot will penetrate the shield until the absorption limit of the shield is reached, make a connection with the holder, and stay in contact with the holder until the holder is pushed backward. The holder will experience a sudden acceleration backward but will feel no ill effects.
However, if the kicking foot contacts the shield with a slight bend in the knee, the result will be a snapping, thrusting kick. The foot will penetrate the shield until the absorption limit of the shield is reached and make a slight penetration into the holder. The shield holder will only move slightly but will experience a quick, powerful jolt that will shake the holder from head to toe. If the kick is done properly, the holder will feel as though his or her eyes are rattling in their sockets, that their tooth fillings have been shaken out, or that, for a moment, they were unconscious; it will not be a pleasant experience.
OverextensionDon’t overextend a punch; you may hyperextend the elbow and sprain it. Overextension weakens the power, exposes you to a counterattack if the punch misses, wastes time and energy, and slows your ability to make a follow-up attack. Always stop just short of the elbow being locked straight out.