The hand-replacement exercise is one of the first Wing Chun principles taught to beginners. It’s an introduction to the concept of “centre line”, using simple body mechanics whilst maintaining forward pressure.
How does it work? Imagine you have your leading hand on someone’s face and he/she tries to block or grab your hand. You basically retract your leading hand and replace it with your rear guarding hand spontaneously.
Practising this simple repetitive chain movement of the arms and hands may appear harmless at first, but it actually helps to establish your foundation in Wing Chun’s simultaneous defence and attack. The hand being replaced could also have been engaged in palm strike, fingers stab, elbow jab, kick, and even grappling.
This hand-replacement technique can be seen at the last section of the first form “Sil Nim Tao” and also at the first section of the second form “Chum Kiu” (which translates as the ‘Seeking Bridge’ form). As you progress through to forms, you will be using body-pivoting and foot-work to increase reach and power.