The Barrie Ryuesi Karate Club has posted a discussion and video of Master Hwa's demonstration of fajing, Thank you Barrie Ryuesi Karate, I discuss this with them here and their comments are enclosed in quotation: Barrie discussion
"Here is quite a good and believable demonstration of fajing, or the explosive delivery of internal energy, by Stephen Hwa, who teaches taijiquan at the University of Buffalo and in Fairport, New York."
Master Hwa does not still teach at the University of Buffalo or Fairport, but he can be reached at firstname.lastname@example.org. Presently, he teaches in Pompano Beach Florida where (while in the springtime of his life) he enjoys Florida's perpetual springtime.
"He shows the “one-inch punch” made famous by Bruce Le (see below), who at the 1964 Longbeach championships knocks someone into a chair, without any windup, his fist starting an inch away from the target." See this link for video of Bruce Lee and make up your own mind: Slow motion of 1 inch punch
I think it is a matter of opinion as to whether Bruce Lee does the punch "without any windup". Notice his fist does start close to the man's chest (near solar plexus?) you see him touch the man's chest a couple of times before delivery of power. If you look carefully you can see the man sway gently as Bruce's fist makes contact on a couple occasions.As he touches the man's chest, Bruce is also seen adjusting his foot stance with his back foot pointing almost 90 degrees out.
"Master Hwa shows how it is possible to generate this power using the taiji “hollow-fist punch.” He explains that other people have recreated this but using “external” or purely muscular power. In his demonstration, he has his "hollow fist with pointed knuckles" pressing against the pad held to another person’s midsection, while someone else holds onto his bicep and forearm, to feel his muscular contraction.
With the "hollow-fist punch" the reasoning is the same as why he maintained a relaxed arm. Bruce's fist is clenched tightly, the arm is extended almost fully. With such a clenched fist the arm cannot maintain relaxation. Try this yourself, clench the fist tightly and notice the effect it has on your arm, then on your body. The use of muscular power is evident in Bruce's punch with such preliminary muscle tension, it is "external" power. When the punch is delivered, one can see him pushing from the back foot as well. Force generated from external limbs such as arms and legs has much longer duration and cannot be compacted into such a burst as possible with "hollow fist" and relaxed arm.
"With seemingly little effort, he knocks back the man holding the pad, who feels a sudden surge of power. The man holding Hwa’s arm says it is relaxed before and after the punch, with only brief tension as the power is delivered into the opponent. Hwa explains that if the arm tenses before the power is delivered that the force will be greatly reduced."
The "knocks back the man" is more detailed than appearance would have us believe. This is so because of Tom's body structure and Master Hwa's as well. Ideally, one has to have a better body structure than the receiver. Bruce Lee has a body structure incomparably better than the receiver who stands flat footed with feet together. Compared to Tom, Master Hwa's body structure is poor and it is the receiver who has better structure. The "reaction force" (Newton's Law of action and reaction) will push Master Hwa back instead of Tom. To explain this better we refer to the term "Peng" which is one of the 13 movements of Tai Chi. Peng for the most part has a major component which is an uplifting force. It lifted Tom partially off the ground, then a minor forward force (the knock back portion) knocked him back. In this case M. Hwa's tight compact and upright stance has the advantage as the reaction force is absorbed straight down the body into the ground. Actually, Tom did not receive all the "explosive" energy possible because of the pad. As Master Hwa demonstrated on an amateur boxer (familiar with body punches) even a punch of reduced power with no pad results in the receiver collapsing (Uncovering the Treasure pp.109). The "tensing" of the arm really just starts at the split second the hollow fist reaches the opponent. Also, Bruce uses the whole fist whereas Master Hwa forms the knuckles into a hollow fist. The analogy is like that of "holding a robins egg". One can imagine that or clenching the fist either before impact or even during would crack the egg, would it not?The hollow fist has pointed knuckles not tightly held and it is designed to strike at soft tissue and not a bony part where it would hurt the fist. The stiffening is a natural response to the feedback of a sensation of resistance". A side note to this is whether the opponent or target is like, or one might say, analagous to a "creampuff" or a "side of beef". In the latter the resistance will be instantaneous thus providing instantaneous feedback to such a pronounced sensation of resistance. If "creampuff" like with no resistance, there will be little or no delivery of power. I had a recent discussion with Master Hwa who is a Ph.D., chemical engineer (and this got really interesting for me) about terms like "time constant".My layman's understanding is that all materials have a "time constant" in their elasticity. Well in this case, the force is coming at Tom (as Master Hwa later says) with so much force, so much speed it creates a "time delay" (irrespective of the "time constant"?) in Tom's body going backwards. Measuring how far the punch penetrates during and after the pad is really only about 2 or 3 inches of compact movement. Regardless of that it still penetrates into Tom's body and one might say completely. I call it an "implosion", on the inside of Tom's body as opposed to an "explosion" on the outside. He receives the whole force before his body begins to move back, so much for "pulling the punch", don't you think? It is aptly called a "spike" of power because like a spike, the opponents body has no chance to get away from the full force. Now, one cannot get "internal discipline" and cultivate "internal energy" by external movement so it has to be learned from the Tai Chi form. In all fairness to Bruce Lee, rip, he might have been pushing the opponent in order not to really hurt him, thus diminishing his force. After all, he did not use a pad and the potential for injury was great because his fist looks like it was spot on the solar plexus. Either way you can come to your own conclusions and I humbly hope I have provided some additional observations based on my own experience as a practitioner/teacher of the art and as the individual who was lightly touching Master Hwa's arm.