What is a "Shock" Punch?

I have often been asked about the legendary/mythical/magickal/fake/bullshido "Shock Punch" which transfers energy into the target without penetration...

Would this not be ideal? One could strike an armored person or a hard, bony target and not injure yourself doing so: "I send my ki into the enemy and he is vanquished" - yeah, right.

Thing is; it is real. What it is NOT is "magick" or "fake" or "bullshido"; it IS frequently misunderstood or poorly taught or poorly performed.

In the following video Wing Chun Master Loi (Macao) explains the Wing Chun Fist, what I consider the epitome of a "Shock Punch".

The Secret of a "Shock Punch":

Tension at the moment of impact followed by immediate relaxation

It has nothing to do with "pulling back" or "withdrawing"; it is simply instantaneous tension and relaxation.

One should always be relaxed when one launches a technique (waza) and only tense the muscles at the point of impact; this allows the body to move freely and therefore quickly. One applies tension at the point of impact to harden the striking surface and to avoid damage; but it is relaxation which determines if the strike gives penetration or simply transfers energy. Master Loi points this out at around 40 seconds in the video (-1.43 on the FB timer).

Anyway, here it is, folks, in plain English (Okay, Chinese with subtitles):