Why Do We Kick Like We Do?

[Hobbes]

Quick question here...why are we talking about a whip? True that I don't particularly wanna get "cracked" with a whip, but I am not trying to bring up a welt with a kick nor tear through skin. I am trying to CRUSH whatever I am kicking, not "flick" it. Also, I don't believe there are near enough joints in the lower body to liken it to a whip anyway- I cannot flex the shin bone, nor the femur, etc. I thought the power in a whip was basicaly because the whip flexed continually while transferring kinetic energy into a continually smaller area (as the whip gets smaller near the business end). I may just be missing your point.

I think the physics behind a swing with a baseball bat may be more appropriate in this case.

Hitman, I think you are getting it. I will say that the femur does flex with stress as does the tibia, but to what degree I can not say. Angular kinetics is not tooooo difficult for simple systems, but when you bring into play the hips, the other leg, the action of the ankle, knee and hip etc.... there are many things that turn what first appears to be a simple thing into a complex skill.

[Hobbes]

Had the opportunity to free spar with a muay thai when I was in Bangkok. This was a mistake, the worse bruised rips and left thigh I have ever had, hands down. My calves were larger than this guy's upper thighs, heh, well, all I can say is that as soon as I realized that this was full on, (I admit I was stupid not to realize this), I ended the match with the first and only technique I threw. A mid thigh round kick and I honestly thought I had fractured the guys leg. This guy scared me.

And Oh... I think I got lucky.

[palatoss]

This is a very interesting discussion. I've always thought of the whip comparison as a metaphor for properly relaxing the legs and arms while kicking or punching. Beginners usually try to punch with the power of the arm alone, the whip metaphor helps them to understand that the arm should be relaxed and power comes from the twist of the hips and waist. It makes no sense to physically compare whip and leg, their mechanics are completely different. The comparison with nunchaku is interesting, though. The mechanical principles in nunchaku and leg are quite similar, especially if the nunchaku has a very short chain...

Somebody wrote that thai kick should be done with a "dead leg". I have no experience in Muay Thai, but for me that sounds like another metaphor for a kick with a relaxed leg. Maybe not so different from a whip comparison used with a Shotokan kick. The biggest difference seems to be that in Muay Thai you commit a lot of your own mass to the kick by "following through" while in Shotokan you are not throwing yourself in to the kick that much, but instead choose to keep good control of your leg.

[Hobbes]

It makes no sense to physically compare whip and leg, their mechanics are completely different.

While I agree with the statment that the antagonist needs to be relaxed and the agonist involved needs to be maximally and co-ordinatedly contracted to produce speed, I do not, however, agree with the quoted statement above. The underlying principles behind the whip and the leg are undeniable. The point that is getting missed her is that we are NOT making a 1:1 comparison with the whip and the leg, but using it as an example to demonstrate how force is transmitted trough a structure to produce a desired outcome.

I believe that all instructors should become certified coaches, fitness leaders, with a pretty advanced knowledge of first aid with a couple basic courses in biomechanics of sport before ever being allowed to get insurance to open a dojo.

A fact which I'm pushing actively.

[TheAnimal]

Unfortunately, the human body does not work in the same manner as a towel. I have a very long winded physical/mechanical description of why these whip/snap/whatever puches and kicks do not aquire much power, but that's the subject of an article I was thinking of writing (upon suggestion).

The principles of the whip (ie the towel) does occur in karate. Techniques are classified as "push" or "throw". A front snap kick is a throw techique, utilizing the summation of forces or large (shortened) masses (levers) rotating around a central point (generally the hip region), when this motion is halted the forces are conserved (conservation of angular momentum) in the smaller lighter segments of the lever producing a much higher velocity. The damage of the weapon is determined by the over all mass of the moving object, its velocity and the contacting surface area.

Basic biomechanics 101

If you like I can supply some excellent references that explains these principles in as much detail as you like.

What you described is a lever-arm. Not anything resembling a whip. The two things are completely different.

[Hobbes]

What you described is a lever-arm. Not anything resembling a whip. The two things are completely different.

I will attempt this again... I did state that I thought that the "front kick" resembled a trebuchet, which I thought was a better example. I have consistantly used "lever", "moment arm", "angular momentum" etc... though out this explaination. I think I've given a decent but extremely brief explaination of the kick. Feel free to disagree, its fine by me. I for one will continue to cite research and can do so on demand.

[Hitman]

Bonus points for using "trebuchet" correctly in a casual conversation

What I'd like to see, would be a scientific conparison between different kicks, and different STYLES kicking methods. Get some different stylists- same basic height, weight, reach, etc- and start blasting away on a pad with a sensor on it to measure impact. I'd buy that video....no wait, I'd download it though

[TheAnimal]

Right- if we're talking front kicks, the trebuchet style you refer to, I sometimes hear it called a snap kick, whatever... is not the most powerful kick. Besides that, I thought we were talking kicks coming from the side, i.e. roundkicks, thai kicks, roundhouse kicks, whatever.

[Menjo]

Right- if we're talking front kicks, the trebuchet style you refer to, I sometimes hear it called a snap kick, whatever... is not the most powerful kick. Besides that, I thought we were talking kicks coming from the side, i.e. roundkicks, thai kicks, roundhouse kicks, whatever.

I see it differently altogether(for most/all kicks). It ends the situation 80 percent of the time for me without any need for follow up, so really in regards of rating. I dont think its relavant, unless you missed? Well lets say you did miss, someone might say that at least you can do some damage right? But thats not the objective, I simply want to end this persons will to fight. Agaisnt an experianced attacker, and strong yet off target technique may not be enough, thats why there are methods of accuracy and training methods to develop such control over a situation... Now the traditionalist view is that it should work 100percent of the time, yet obviously I'm NOT a master so thats why I said that. If you use it correctly, who cares what amount of power you had. Unless its part of your training I guess.

This has completly gotten off course and I realize that so cut me some slack .

Edited February 11, 2006 by Menjo

[Hobbes]

Right- if we're talking front kicks, the trebuchet style you refer to, I sometimes hear it called a snap kick, whatever... is not the most powerful kick. Besides that, I thought we were talking kicks coming from the side, i.e. roundkicks, thai kicks, roundhouse kicks, whatever.

Yes I was referring to a front snap kick exclusively. A thrust kick is a push motion, as apposed to a throw motion.