Capoeira Kick

[Flying Crane]

Force is Mass * Acceleration. Energy is K.E. = 1/2M * V^2. Since his mass is relatively small and his velocity is very high I would use the energy formula to compare the two. I think it works either way though.

When dealing with biological bodies that have a lot of variation in their size and positioning and weight placement and ability to bring strength into play and whatnot, I think using standard physics equations is not a proper use of the science. While they are not entirely separate, it is much more messy to try and make a comparison in that way. The physics works well when describing motion of a particle or a particle-like body, but not so clean when describing partial motions of connected portion of a biological body.

 

[Flying Crane]

Now you're specifying a system of measuring the energy, which was not the case before. And you are also implying taking that measurement at the moment of impact and ignoring what follows.

And while force is indeed mass X acceleration, you need to account for the effective mass in a push kick.

Following the initial impact (where the mass is equal to a turning kick, i.e. the leg, but the velocity is inarguably lower) you have the mass of the body, plus the strength of the leg muscles pushing that mass forward quickly, which increases Mef markedly.

Just stood up, yeah, I'd likely prefer to take a push kick because I can move with it far easier.

My back against a wall though? That's a different matter.

I would say it depends on how well the initial impact is delivered, before the follow-through. A thrusting impact vs. a swinging impact, I don’t think it is possible to automatically judge one as inherently better than the other.

 

[dvcochran]

When dealing with biological bodies that have a lot of variation in their size and positioning and weight placement and ability to bring strength into play and whatnot, I think using standard physics equations is not a proper use of the science. While they are not entirely separate, it is much more messy to try and make a comparison in that way. The physics works well when describing motion of a particle or a particle-like body, but not so clean when describing partial motions of connected portion of a biological body.

How would you suggest to coalesce the data?

 

[pdg]

I would say it depends on how well the initial impact is delivered, before the follow-through. A thrusting impact vs. a swinging impact, I don’t think it is possible to automatically judge one as inherently better than the other.

Either could be better, there are too many variables to get anywhere near a "best kick" debate.

The only time you can ever do that is to line some people up and see who can spin the dial the most - thereby giving you "best kick under this specific circumstance and system of data collection"...



Edit: there's also what is best for the situation you're in. And that could be anything.

 

[dvcochran]

Put your car on a level surface, in neutral and with the handbrake off.

Perform a push kick to the bumper.

I bet the car moves.

Now try to move it with a roundhouse. Get anyone to try moving it with a roundhouse, including the 3 guys in that video.

I can move my Land Rover with a push kick, but I can't move it with a turning kick. Conversely, I can perform a much more effective break with a turning kick.

That's a measurable difference right there.

It also takes a minimal amount of force to stop the car, i.e. stopping the push kick. Whether it be stopping the forward motion by interfering with the inherently slower motion of the kick, redirecting it, or just getting out of the way. Any of three is much harder with the roundhouse. You can also absorb the force of the push kick much easier than a roundhouse kick, especially to the head. Being hit with a pillow vs. a hammer.

 

[dvcochran]

Either could be better, there are too many variables to get anywhere near a "best kick" debate.

The only time you can ever do that is to line some people up and see who can spin the dial the most - thereby giving you "best kick under this specific circumstance and system of data collection"...



Edit: there's also what is best for the situation you're in. And that could be anything.

Well, that is what the video was claiming to do, albeit with very flawed and biased data.

 

[Flying Crane]

How would you suggest to coalesce the data?

I don’t know. I just know you can’t plug in the standard physics equations and get an answer that is clear and clean.

Two different people doing the same kick, especially a kick with a lot of “moving parts” like that particular capoeira kick, can have very different results based on their physical capabilities and proficiency with that kick.

For example, I think basic requirements of the physics, such as “mass” would be extremely difficult to determine for such a kick. It isn’t the mass of the person’s entire body. It isn’t the mass of the foot or the leg. It is somehow the engagement of the body to whip out the leg and foot, from an unusual physical position and balance point, with varying physical strength and proficiency. I don’t begin to know how to actually measure “mass” in that case.

 

[Flying Crane]

Either could be better, there are too many variables to get anywhere near a "best kick" debate.

The only time you can ever do that is to line some people up and see who can spin the dial the most - thereby giving you "best kick under this specific circumstance and system of data collection"...



Edit: there's also what is best for the situation you're in. And that could be anything.

That is exactly what I am getting at. Sounds like we are saying the same thing.

 

[Flying Crane]

It also takes a minimal amount of force to stop the car, i.e. stopping the push kick. Whether it be stopping the forward motion by interfering with the inherently slower motion of the kick, redirecting it, or just getting out of the way. Any of three is much harder with the roundhouse. You can also absorb the force of the push kick much easier than a roundhouse kick, especially to the head. Being hit with a pillow vs. a hammer.

See, this is where the semantics are meaningful, in my opinion. That “push” isn’t hitting with a pillow. It is hitting with a battering ram. It is only a push if you place the foot on the target and then push. But if you strike the target and drive through, there is nothing about it, in my opinion, that is a push. As examples, I would point to a side thrusting kick, a back thrusting kick, or a front thrusting kick with the heel of the foot.

 

[pdg]

See, this is where the semantics are meaningful, in my opinion. That “push” isn’t hitting with a pillow. It is hitting with a battering ram. It is only a push if you place the foot on the target and then push. But if you strike the target and drive through, there is nothing about it, in my opinion, that is a push. As examples, I would point to a side thrusting kick, a back thrusting kick, or a front thrusting kick with the heel of the foot.

And I would say that all those examples have a pushing element

 

[dvcochran]

See, this is where the semantics are meaningful, in my opinion. That “push” isn’t hitting with a pillow. It is hitting with a battering ram. It is only a push if you place the foot on the target and then push. But if you strike the target and drive through, there is nothing about it, in my opinion, that is a push. As examples, I would point to a side thrusting kick, a back thrusting kick, or a front thrusting kick with the heel of the foot.

Agreed, but I was using @pdg's pushing a car analogy.

 

[dvcochran]

I don’t know. I just know you can’t plug in the standard physics equations and get an answer that is clear and clean.

Two different people doing the same kick, especially a kick with a lot of “moving parts” like that particular capoeira kick, can have very different results based on their physical capabilities and proficiency with that kick.

For example, I think basic requirements of the physics, such as “mass” would be extremely difficult to determine for such a kick. It isn’t the mass of the person’s entire body. It isn’t the mass of the foot or the leg. It is somehow the engagement of the body to whip out the leg and foot, from an unusual physical position and balance point, with varying physical strength and proficiency. I don’t begin to know how to actually measure “mass” in that case.

I would say the mass would be fairly consistent given 2 people of the same build and body type. The mechanics of how each person performs the kick would vary greatly so your argument is sound.

 

[pdg]

It isn’t the mass of the person’s entire body. It isn’t the mass of the foot or the leg. It is somehow the engagement of the body to whip out the leg and foot, from an unusual physical position and balance point, with varying physical strength and proficiency.

The mass is the mass, you don't change that with technique or anything else.

It's the mass of the foot, lower leg, upper leg and core, in varying degrees.

The bit that changes and hugely affects the force is the velocity of the strike, which is also the bit that's almost impossible to state as a constant.

 

[Flying Crane]

And I would say that all those examples have a pushing element

I see your point, but the difference is what does it start with? Is it an impact, or a placement?

 

[Flying Crane]

I would say the mass would be fairly consistent given 2 people of the same build and body type. The mechanics of how each person performs the kick would vary greatly so your argument is sound.

Yeah, then it comes down to who has greater proficiency with the kick, perhaps some physical strength that is particularly relevant to that kick, etc. these are things that cannot be controlled for when trying to objectively evaluate a kick. You can evaluate the person, but not the kick.

 

[Flying Crane]

The mass is the mass, you don't change that with technique or anything else.

It's the mass of the foot, lower leg, upper leg and core, in varying degrees.

The bit that changes and hugely affects the force is the velocity of the strike, which is also the bit that's almost impossible to state as a constant.

I disagree. Part of the mass of the body is directed toward the ground. Part of it is being launched into the kick. Part of the mass of the leg and foot are being whipped into the kick. And it all changes every microsecond of the duration of the kick. How can that be evaluated, in a meaningful way?

 

[pdg]

I disagree. Part of the mass of the body is directed toward the ground.

Hence me saying "to varying degrees". It'll be a percentage of the total.

Part of it is being launched into the kick. Part of the mass of the leg and foot are being whipped into the kick. And it all changes every microsecond of the duration of the kick. How can that be evaluated, in a meaningful way?

The mass doesn't change - the mass is the mass irrespective of whether it's moving or not

It remains constant throughout the kick, it's the same as it was before the kick was started and the same as it is after it's finished.

That's the thing about mass...

Take a rock with a mass of 1kg. It's 1kg. Throw it in the air, it's still 1kg. Bury it, it's still 1kg. Put it on a table, it's 1kg. The only way to change it's mass is to chip some off or stick more on.

Likewise with the mass of the body parts to perform a kick - the only way to change the mass is to chop some off, or add something (like a shoe). But, unless you lose a toe or put in a shoe during the kick, the mass doesn't change.

Weight and force on the other hand, they can change. You can change the weight of a 1kg rock by increasing or decreasing it's altitude. You can change the exerted force by dropping it on the table instead of placing it.

That's how a kick works - it doesn't change the mass but it uses the velocity of moving the mass to magnify the force.

 

[Flying Crane]

Hence me saying "to varying degrees". It'll be a percentage of the total.



The mass doesn't change - the mass is the mass irrespective of whether it's moving or not

It remains constant throughout the kick, it's the same as it was before the kick was started and the same as it is after it's finished.

That's the thing about mass...

Take a rock with a mass of 1kg. It's 1kg. Throw it in the air, it's still 1kg. Bury it, it's still 1kg. Put it on a table, it's 1kg. The only way to change it's mass is to chip some off or stick more on.

Likewise with the mass of the body parts to perform a kick - the only way to change the mass is to chop some off, or add something (like a shoe). But, unless you lose a toe or put in a shoe during the kick, the mass doesn't change.

Weight and force on the other hand, they can change. You can change the weight of a 1kg rock by increasing or decreasing it's altitude. You can change the exerted force by dropping it on the table instead of placing it.

That's how a kick works - it doesn't change the mass but it uses the velocity of moving the mass to magnify the force.

But a rock acts like a particle, while in the context of doing a kick, a human body does not. It is not moving in unison.

Mass overall does not change. However, the portion of the body’s mass that can be used to predict force, that portion directed into the technique, is not the complete mass of the body. And every time a person does the same technique, it is likely to be different in a way that cannot be predicted in a regular and accurate manner. The performance of a human body varies every time.

 

[dvcochran]

Yeah, then it comes down to who has greater proficiency with the kick, perhaps some physical strength that is particularly relevant to that kick, etc. these are things that cannot be controlled for when trying to objectively evaluate a kick. You can evaluate the person, but not the kick.

Well, I have to disagree with you last statement. I assume you are an instructor or have done your share of teaching and know how many hours are spent on students with just one kick. Everyone can improve from where they started. Some start way ahead for many reasons, physical, mental, etc... Kicks have evolved and improved over the years. Just like the Capoeira kick.

 

[dvcochran]

The mass is the mass, you don't change that with technique or anything else.

It's the mass of the foot, lower leg, upper leg and core, in varying degrees.

The bit that changes and hugely affects the force is the velocity of the strike, which is also the bit that's almost impossible to state as a constant.

Regarding the video, I believe the roundhouse kick was about 30 mph faster.