When you take all the magical rubbish away, fajin ( ē¼å ) really just boils down to explosive "short power".Experienced it a couple of times, and got knocked own by it. Not really sure how you would differentiate a punch/strike from a push, but the impact felt instantaneous, like a hit rather than being moved by a push.
In our training this āone inchā force generation thing isnāt really used as a strike, but to disrupt and set up take downs in a stand up grappling situation. Our āpush handsā rules donāt allow for strikes so these sneaky one inch jolts are used to āskirt the rulesā.
Example in the video below:
This is not strictly about one inch punches but just short /no distance techniques used for such purposes.
Short power, the ability to generate and transmit damaging force in a short distance, is very useful in both striking, grappling, and weapons arts. Of course we train it in Wing Chun, and also in Latosa Escrima, but I see it in boxing and wrestling too.
As ZZJ points out, it's not just for punching. If you can "jolt" and unbalance your opponent ....or even just make him tense-up, new opportunities emerge.