As we look at this photo of a bullet travelling through gelatin, we are allowed to see the very difference between conventional ballistic attack and that of Kyusho.
If we see the cube of gelatin as the human body and the distortion as the affects of a ballistic strike on that body we gain a very valuable insight. With a heavy blow from fist, elbow, knee or any blunt weapon, we see that at the surface and even interior, there is a massive trauma or expansive affect on that structure. It's force is captured and absorbed as it dissipates within the structure at the point of impact. Yes it damages the tissue or integrity but is solely dependent on the amount of force utilized.
The idea of Kyusho which can be depicted by the bullet traveling on a path through the target on a specified path through space and object, is vastly different. But first we must get terminology straight as the confusion lies with this.
In Kyusho the typical manta is "Angle and Direction" and on the surface, (pun intended), this is a valid approach, yet very limiting.
Angle: translates into the way your weapon approaches a specific target (some still call a pressure point), it is a descriptor of your physical action. This is from a starting position to a finishing position, front to back, high to low, low to high, right to left or left to right, etc.
Direction: translates into a course along which someone or something moves and can mislead the new practitioner in the study of Kyusho. It is also why many try fruitlessly to realize great affects but fall short... unfortunately also why many give up, stating that Kyusho does not work.
The better definition that helps people not only understand to a higher degree, but also enables them to actuate Kyusho affects more effectively and efficiently is "Trajectory".
Trajectory: is the path followed by a projectile flying or an object moving under the action of given forces through space or object. In Kyusho that is everything as we seek to send our kinetic energy toward a specific path in the human body not at the site of impact, but deep into the core. We do not seek to traumatize the exterior or the shell of the body and all structures, instead we seek a trajectory along an accessed structure to the core. In Kyusho this is the central nervous system (spinal column and brain), via the nerves.
This is why there are no injuries in Kyusho as we are not using, nor do we need, heavy blunt trauma or power. Yes Kyusho will still work like that as this picture also illustrates, the damage can be inflicted and the trajectory also realized. But in the training the importance is placed on the trajectory and reaching the core with as minimal a force as possible. Once that is trained and ingrained, adding force (if ever needed) will of course multiply the affects (and legal issues)... for a even more reliable protection.
We see in MMA now the hard realities of this as well. We see the heavy force and brutality, that is often absorbed and fought past... but every so often we see the proper trajectory used in a location that even with less power, incapacitates the opponent. But this and most Martial Arts are of this Yang nature and is not concerned with the inner workings as much as destroying the outer aspects.
And as a Yin comparative, we look at the skill of Kenjutsu (剣術) or the Japanese Sword styles. They do not use force to make their cuts, but instead use trajectory to go through the outer... this is what Kyusho is all about, or should be.
It is not the power, it is not the angle or direction... it is all in the trajectory.