Sifu B is a former US Marine, with almost 40 years of martial art training. He is ranked in 4 styles.
There is a famous scene in the movie Bloodsport. Frank Dux presents his invitation to the officials to enter the underground fight. They doubt his lineage and request he prove he was trained by the teacher. They tell Frank to demonstrate a technique.
“Show us the Dim Mak…Death touch.”
Frank approaches a stack of bricks. Before he can strike the brick on top, they say to him, “Bottom one.” Dux hits the top brick with an open palm and the bottom brick explodes into shards.
There are errors we must clear up. First, the demonstration is not “Dim Mak.” What the character is demonstrating is selective breaking. This sort of breaking is in “Iron Palm” styles. Secondly, and this error is more common, Dim Mak does not mean death touch. The literal translation is “spotting blood.” The term is best understood as “press point.”
The origin of Dim Mak comes from Chinese acupuncture. There are over 1000 acupuncture points. Of those points, 108 can produce serious and even fatal affects. There are points in acupuncture which are completely forbidden to needle. These points include the fatal ones of Dim Mak.
You are familiar with the “funny bone.” You may have hit your elbow at a certain angle. This results in a dull, tingling sensation. It feels funny. The funny bone is not a bone at all. This is the ulnar nerve. It lies between the elbow joint and the humerus bone. The ulnar nerve runs from the brain to down the back of the forearm, through the palm and back of the hand. The nerve sends signals from the brain which controls the pinky and ring finger, hand grip, and fine motor skills of the hands. Hitting the elbow causes the nerve to strike against the humerus bone, and this sends feedback to the brain.
The funny bone is not a Dim Mak point. But this is one way to demonstrate how you can affect the nervous system of the body. And these effects are involuntary.
Dim Mak originated in the soft systems of the Chinese arts (internal martial arts). It was later adopted in the Shaolin School and spread outside of China. Dim Mak was adopted by other arts (Karate, Wing Chun, Kenpo, etc.) as “pressure points.” Much of this is not Dim Mak. It is more on the level of striking the funny bone. There are those who claim that there are certain points on the body which, if struck or pressed, can cause a “knock out.” The majority of these claims are out-right lies. They have nothing to do with Dim Mak.
The pressure points cause pain and can be used for compliance. You can experience one such point for yourself. Put your finger behind your ear lobe. Notice that there is a hollow area there. Now, turn the pad of your finger toward the back of your head and press in on the lobe of the bone. Dig your finger in deeper and press harder toward the back of your skull. This is an example of a pain point or pressure point.
Granted, Dim Mak is much more complicated than this, but this is one way to begin to understand it.
Understanding human anatomy is an important part of martial arts. If we know the natural weak spots on the body, then we may be able to exploit them to our advantage. There is nothing magical about this. Even in martial sports, we can see examples.
Let us consider the “liver punch” in boxing. The liver is a large organ that extends below the rib cage. This punch is often landed inadvertently. A well-placed strike can have a delayed effect. The opponent is struck on the left side of his body and will crumple to the ground. The punch does not have to be powerful, just well-placed. The average person can punch at 6 meters per second. A professional fighter can double this speed. A well-placed liver punch, traveling only 5 m/s, is enough to bring down the biggest man.
Take a look at the Bas Rutten and Jason Delucia fight. The fight ended when Rutten struck the body of Delucia. It was later learned that Rutten ruptured Jason’s liver. This amount of damage is not necessary to stop a fight. The reason why many collapse is due to a response of the autonomic nervous system. Remember the funny bone? The same thing happens here. When the liver is stuck, certain nerves are stimulated. These nerves send signals to the brain to reduce blood pressure. The mind tells the body to lie down to protect itself. The person may even become unconscious. We should note that the liver is not the only organ which can be effected in this way.
There is a legend that says a person can strike a certain point at a certain time of day, and over a course of time, the person will die. This is mostly the stuff of ninja fantasy. However, we should consider the origin of such a myth. Consider the case of Harry Houdini. Harry was famous for being able to take a punch to the stomach and remain unharmed (“iron body”). One day a man hit him before he was ready. This caused a hemorrhage that killed him. Others say he died of a ruptured appendix. Either way, we can conceive of the possibility of a person receiving an internal injury that later kills them. This would likely happen before the creation of modern medical diagnostic equipment.
There are Dim Dak techniques that can cause unconsciousness and even death. These effects are not mystical; they're based purely in physiology. However, most of what is taught as Dim Mak is fit only for Hollywood.