Biomechanics of Jumping Kicks?

[Useless]

I'm hoping to find some information about the biomechanical advantages and/or disadvantages of flying/jumping kicks versus grounded kicks--most specifically in breaking boards (so speed and power generation, not necessarily practicality). I've done some searching about the forum and haven't been able to find much relevant. Does anyone have any good books to recommend or leads to try and follow?

In the interest of full disclosure, the essay I'm looking to write is part of the pre-test for my black belt. I'm part of an multi-discipline school (I hesitate to say MMA for all it connotes) and TKD is one facet of our training.
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[StuartA]

GM Hee Il cho has some great books out on kicks/jumping kicks.. these may be of use.

I could give you my opinion... but I'm neither a scientist or a Master, so thats all it would be.. which i dont think is what you are looking for really.

Stuart

 

[ATC]

Not sure about the science behind it but my take on why to use jump kicks was because of height and distance. Jump kicks were used to knock people off horses and from behind obstacles. For the most part they are not practical today but are mainly tradition and demo or show. Jumping side kick is still good if your opponent is stationary and not mobile at all. Jump back kick and jump back spinning heel are good defensives kicks. Other than that there are not much uses for the other kicks.

Unless you are knocking down doors or kicking cats out of trees that is.

 

[StuartA]

Jump kicks were used to knock people off horses ....

Sorry... Martial Myth!!! :shock:

 

[terryl965]

The reason fo the jumps kicks are simple they look cool in the movies, especially in slow motion.

Yes Stuart the jumping and kicking men ofd od horse is one of the biggest myth we have.

 

[Omar B]

Sorry... Martial Myth!!! :shock:

What? Never jump kicked a guy off his horse? Harley? You need to get out more. LOL

 

[bluekey88]

Neither a scientist or a master either...but here's my take. Jumping kicks have a lot of power because you pretty much get all of your body weight behind them when done right. They do NOT have as much power as agood grounded power kick...because you're not connected to the earth in the former, while oyu have that as a base in the latter.

Jumping kicks serve two puposes for me. 1) To cover height/distance. 2) to suprise.

Jumping kicks let me get slightly easier head shots. Also, most jumping kicks involve the use of the back leg as a power generator. this can be thrown like a fake kcik and can often distract the oppoenent into reacting and opening up for the actual kick.

This is pretty much for competition though. Not something I'd use in self-defense.

Peace,
Erik

 

[Earl Weiss]

You can search some topics such as "Closed Chain exercise" or "Kinetic Linking" which will give some info as far as body mechanics and being firmly grounded as some martial arts call it. AFAIAC it is also related to Geral Choi's concept of "Sine Wave" and Bruce Lee's description of the one and two inch punch techniques.

You could contrast that principal with the factors that are missing for non grounded techniques.

These are very difficult things to comapre since the Human Body is a very complicated machine and using typical mechainical models does not always produce a proper result. One of my favorite articles where they acknowledge screwing this up is "The Physics of Karate"

Phisicists are like weather predictors and economists. Not so good at having their theories predict results, but really good at explaining hpow they were wrong.

 

[Useless]

Erik:
Couple questions/comments from my perspective:
I'm surprised by your estimate(?) that flying kicks don't have the power that grounded kicks do. Intuitively, a perfectly executed flying kick would have more power than a grounded kick because you've already pushed off the stable base and can then turn your whole body into the kick. With one leg on the ground, it's physically impossible to throw your entire body weight into it, as some of it is still in contact with the earth and is displaced there. At the moment of impact (especially for power kicks) I can see the connection to the ground being important to continue pushing through the kick. However, for speed breaks, where only initial contact force matters (unless I misunderstand the principle) I can see a possible benefit of throwing everything into that first contact as you don't gain anything by being able to push for that follow through.
The second point is that I have a much harder time kicking as high when I am jumping as when I am grounded--though that's likely a personal defect that I can't get my 250+ lbs off the ground...:duh:

Earl and Stuart -
Thanks for the leads, I'll definitely look into those.

 

[terryl965]

Useless remember that flying kicks also loose power while you are in the air so the point of impact is not as effective as a grounded kick. By the way a grounded kick also allows you to be stable to be able to throw more kick after you hit the target. Most jumping or flying kicks need you to get readjusted before making another kick and gence you loose some valuable time in the crucial time of a fight or SD.

 

[ATC]

Sorry... Martial Myth!!! :shock:

Yeah, I was fed the kool-aid. Did some research and also asked my Grand Master and he told me to try it and laughed.

 

[Useless]

Terry:
I don't see why kicks would lose power while they are in the air. The power is released with the snap of the leg, and in the case of a jump front kick, I can definitely see the initial impact being greater if you kicked on your way up (though definitely less on the way down) as your momentum from the jump is adding to the kick. With horizontally impacting kicks (side kick, hooks, etc) I can't think of any difference in power at any point in your jump, so it seems irrelevant there as well. I'm curious to hear your take on it.

And yes, as far as reset times and stability go, I can see the drawback there--I am exploring the benefits/drawbacks in regards to breaking so fortunately that's not an issue.

 

[Marginal]

Not sure about the science behind it but my take on why to use jump kicks was because of height and distance. Jump kicks were used to knock people off horses and from behind obstacles.

Both are extremely unlikely. A spear works far better in both scenarios. (Even if you assume horses were only 3 feet tall back in the day.)

Jumping kicks at the most basic accomplish one thing. Kicks have the best range and power coming straight off your hip. You jump, you can apply your best range and power to a target other than hip height. It also tends to bring in more downward force to a kick. (Just my impression from holding pads, but you get a definite feeling of downward suction on a jumping side kick that a standing side kick lacks for example.)

The trade off is you have no base. Someone jams the kick, counters with a standing kick, punches you etc, and you're sailing backwards. It takes very little effort to disrupt a jump kick.

 

[Stac3y]

Jumping side kick is still good if your opponent is stationary and not mobile at all.

I've used a one step flying side kick to score on the face of a sparring opponent who was cornered (she was trying not to get a foul by stepping out of the ring.) It was more to cover ground quickly than for height, though she is tall.

 

[igillman]

I find a jump kick provides less power for me than a regular kick. However, I can reach a little higher with a jump kick. For me I see a big difference in a back kick. I can perform a jumping back kick far quicker than a regular back kick. I can twist faster in the air than I can with one foot on the ground.

 

[terryl965]

Useless mainly I say that they loose power because so many people already snaps the kick way to early on jumping kiciks. They do not have proper timing to be efeective with it. Also if you wait to late you are not able to extend the kick at the right point of impact.

 

[punisher73]

Is this more of what you were looking for? It is a clip from Human Weapon, and they break down the mechanics of the kick and how much force it generates.

 

[ACJ]

Terry:
I don't see why kicks would lose power while they are in the air. The power is released with the snap of the leg, and in the case of a jump front kick, I can definitely see the initial impact being greater if you kicked on your way up (though definitely less on the way down) as your momentum from the jump is adding to the kick. With horizontally impacting kicks (side kick, hooks, etc) I can't think of any difference in power at any point in your jump, so it seems irrelevant there as well. I'm curious to hear your take on it.

And yes, as far as reset times and stability go, I can see the drawback there--I am exploring the benefits/drawbacks in regards to breaking so fortunately that's not an issue.

Hmm, try doing a jumping front kick (snap kick, whatever) and then try doing a jumping front kick while holding on to a couple of metal bars or some other hard surface and pushing upwards as you jump. Which feels more powerful?

Not quite how the physics of it works, but it's close to give a basic understanding.

 

[Useless]

Human Weapon--not sure how I missed that show before--I guess one of the (few) drawbacks of not having cable/satellite. I did find the National Geographic "Fight Science," which, while interesting wasn't full on what I wanted.

ACJ:
I'm not sure where you're going with the metal handbars--how high of a surface are you suggesting I should be leveraging against? The problem I see with that experiment is that depending on how the bars are situated you'll be unable to fully turn with the kick or otherwise impede motion.
It sounds like you're recommending getting more power to the initial jump and comparing the power of the kicks from that, but I can't think of a way of doing that without losing proper body positioning with the kick.

 

[ACJ]

ACJ:
I'm not sure where you're going with the metal handbars--how high of a surface are you suggesting I should be leveraging against? The problem I see with that experiment is that depending on how the bars are situated you'll be unable to fully turn with the kick or otherwise impede motion.
It sounds like you're recommending getting more power to the initial jump and comparing the power of the kicks from that, but I can't think of a way of doing that without losing proper body positioning with the kick.

The point was showing that a constant upwards applied force (pushing down on the bars,) would increase the power of a kick. Which mimics a standing kick with one foot remaining on the ground to apply an upwards force. In there are some physical things that wouldn't quite work, but it's the best way to explain it without getting super complex.