Wing Chun is based on the theory of economy of motion. The idea is to move as little as possible when defending, so that your energy is conserved and your actions are quicker.
A principle in Wing Chun is to attack and defend at the same time. Try not to employ two or more steps to handle an attack. The more complex an action, the more chance that the opponent will counter your action before you complete it. The sooner you can counter-attack your opponent, the safer it is for you. It is much easier for the opponent to keep attacking you than it is for him to also defend.
In movie style fighting the opponent throws a punch, the defender blocks the punch, hits back and then stops to await the opponent's next move.
In realistic fighting this two step stop and start action is too slow. Wing Chun employs continuous non-stop hitting. Once you hesitate, even for an instant, you are bound to get hit.
Continuous fighting is developed in the sticking hands training. First you learn simple techniques; then you learn to string them together into sentences or continuous sequences; next you learn to apply these sentences in accordance with the opponent's movements.
Whenever you are stuck, don't hesitate, change immediately to another movement. A useful drill is to have your partner hold out two arms while you continuously apply slapping, grabbing, and hitting actions. This is difficult at first, but comes with practice.
An attack can be defined as any kind of force coming your way. Your opponent is unpredictable, meaning that an attacking force can be directed to any area of the body.
Wing Chun reduces the complexity of trying to intercept an attack by dividing the upper body into four quadrants or regions. The four quadrants are defended by the arms which are strategically placed so as to reach any quadrant in the same amount of time. With the elbow remaining fixed in the center, the time to intercept an attack or to recover from a mistake is reduced.
The region below the four quadrants is not defended by the hands, but is defended by means of intercepting leg movements or by means of moving the stance to evade the force.
From a side view, Wing Chun further divided the body into a front guarding region and a rear guarding region. An attack which slips past the front guard is caught by the rear guard.
In Wing Chun we normally have two lines of defense in the form of a front guarding hand and a rear guarding hand. In Cantonese, the guarding hand or hand of protection is called a Wu Sau.
If you occupy the center with a guarding hand, it is difficult for the opponent to attack. The opponent must somehow go around the guarding hands to attack.
If the opponent attacks to the upper left or right gates, we can use the Tan Sau, Kwun sau, Bong sau or a center line palm hit to defend.
If the opponent removes the guarding hand, we replace it with the other hand. If both hands are trapped, then use body shifting or elbow techniques to break out. If this still fails, then wait for an opportunity to attack.
"The muscles are used to attack, the structure is used for defense". What does this mean?
If you use your muscles to push against an incoming force, your muscles are tense and cannot be used for attacking until they relax. Therefore, Wing Chun likes to keep the muscles in a relaxed state at all times.
If you place your bones at certain angles, you can deflect an incoming force while still keeping your muscles relaxed. Therefore, they are always ready to hit, grab or jerk.
Against a strong forward force, use a structural technique and not a pushing force to control it. A Fook sau is an example of a structural hand technique which can be used to control a strong force while keeping the muscles relaxed.
The Wing Chun Kung Fu Digital Library