Mai Jiang is best explained by using the first section of Siu Nim Tao (little idea form).
The first section of Wing Chun’s form, Siu Nim Tao, contains movements that essentially require the pressing forward of Fuk Sao (controlling/ bridging hand). These three movements as a whole are termed Saam Pai Fut (three/bow/Buddha), meaning “praying three times to Buddha”. In each occurrence of the movement the emphasis should be placed into the elbow, and not the wrist, using the Mai Jiang principle literally meaning pressing the elbow inwards and forwards. This results in the hand/ wrist moving forward in a straight line from the central position with a gentle rising action to the finishing position with the wrist just below throat height and the elbow on the centre line roughly about a fist, to a fist and a thumb, distance from your chest.
Repetition of this movement enables the end position, and the path to and from the end position, to be impressed on the body for future reference using muscle memory. While the retraction is important, for the purpose of this article, it is suffice to say that the elbow returns to a resting position alongside the chest with the hand/ wrist returning to a position approximately a fist, to a fist and a thumb, distance front of the chest, on the centre line, in Wu Sau (protective hand). Practice of the Mai Jiang principle is then repeated a minimum of three times for the form but can be executed as many times as you want in your personal training.
The purpose of this first section of Siu Nim Tao is to impress upon the practitioner the importance of pressing inward as well as forward and vice versa while improving our Gung Lik (energy that hard work produces). Pressing only forward may result in your elbow being off the centre line leaving space for an incoming attack. Pressing only inward may result in a lack of focus toward your opponent, resulting in impaired ability to execute a strike quickly when the opportunity arises. Muscle memory gained in this movement will also raise your awareness of when the elbow is not in the correct position and give an early warning to adjust or change techniques.
The principle of Mai Jiang is very important and you must know how to use it to your best advantage. This is, however, only one of the principles of Wing Chun that must be practiced to increase our skill level and allow us to tap in to the power of our art. Ultimately we have to balance all of the Wing Chun principles according to our specific needs to create a style that works for us as individuals.