"I still feel we should be able to identify major traits that quantify or qualify as internal or external. What are some essential qualities or traits of internal or external that seem clearly unique and mutually exclusive?"
"How about:
* Relaxed vs. Tensed
* Capturing energy vs. Applying energy
* Whipping/circular vs. Linear"
John C
As far as "relaxed vs tense," I have never studied a purely internal art (though I've done some Aikido which fell more into the "soft vs hard" style dichotomy, but I know that in the striking I study in the Filipino arts, Jun Fan Gung Fu, and the bit of Muay Thai, you are supposed to remain relaxed at all times except for the instant at which your strike lands. I have also been told by an amateur boxer that boxers also try to remain loose and relaxed even as they punch, except when they actually hit, in the same manner.
As far as I can tell, to be tense is to be slow to react, inhibits sensitivity and spontenaity, and is much more tiring than being relaxed. I can't see how that could be good in a self-defense situation, though it would do great as an isometric exercise, I suppose.
I wouldn't mind a bit of having "capturing energy vs. applying energy" defined. I am under the impression that some strongly
internal arts use punches, kicks, and/or other strikes. Such techniques seem to involve applying energy.
As far as "whipping/circular vs. linear," I'm not sure what that means. If hook punches and roundhouse kicks are circular, well, hard styles have 'em. Hsing I is, as understand it, actually tends to uses linear punches as its main attack. Wing Chum and Jun Fan both use some circular parries, and, as I said, and they are not generally regarded as internal arts.
"My original point on the observation of each art having aspects developed for their
purpose was simply to suggest that boxing may have aspects of biomechanics geared a certain way because of the rules of the sport, the arena, the overall goal, etc. that will intrinsically differ from a training technique from another art geared along a
different purpose."
John C
Boxers still aim to produce the most energy possible in their punches, sport or no sport. Muay Thai and in the Filipino arts (at leas the ones I've had exposure to), employ basically the same biomechanics, as do some other arts. Basically, you try to use the entire body to power the punch, as has been discussed before. Increases efficiency for maximizing power, etc,
If you describe specifically how boxers' biomenchanics may be significantly different due to the rules that they operate under, I'll see if I can talk to one of my martial arts instructors with boxing experience (I have a couple), and see what their boxing and martial arts experience leads them to believe.
"I'm not sure I agree with your conclusion that since biomechanics deal with what is
within the body they are inherently "internal". Perhaps another way to say this would be that both external and internal styles offer differing approaches to biomechanics. I don't know ..."
John C
I had a smiley after my statement. It was a joke.
John Thurston had it right when he speculated about what I meant by sensitive grapplers (no, not crying while watching romantic movies and loving kittens

When one grapples (at least where I study -- the Filipino empty-handed stuff I do involves lots of standup grappling and more than a bit of groundfighting too, and the Jun Fan does also, but with less groundfighting. I have done a bit of other grappling in other styles too, but not enough to speak in an informed manner on them), one has to pull when the opponent pushes, but in the right direction, and to the right degree, or push when an opponent pulls. This requires sensitivity. Also, you have to be sensitive to sudden movement, wether your opponent is balanced, and other things I'm probably forgetting now.
Much grappling training (at least where I train (where being tense or stiff is considered undesirable)), involves the ability to sense how an opponent is trying to apply energy, and making use of that by turning the tables on him. If they want to go in a particular direction, you let them, and help them along, but make use of their direction to throw them, lock them up, get them into a choke, or otherwise defeat them.
As I've said, both the Filipino arts and Jun Fan employ sensitivity drills. In both the ability to flow smoothly between strikes, traps, and locks, and between one lock and a reversal (an "opposite" lock) are emphasized here. All these things tend to be done as "targets of opportunity," based on what the opponent "gives" you, and very sensitivity based.
I've seen Brazillian Ju Jitsu types grapple too (only one lesson in this style on my part), and sensitivity to what an opponent does seems to be a pretty important element with them too, though I lack the experience to say this as a fact.
I don't mean to be a curmudgeon.
Scaramouche