How do they sheer through huge lumps of stone, ice or wood with their hands or head?
Should have phrased that “How do they sheer through huge lumps of stone, ice or wood with their hands or head without injuring themselves?”
My understanding (and I could be way off on this one), is that they learn how to distribute the force. I assume everybody’s seen the trick on TV where the guy comes down with the side of his hand through a block of concrete. I’ve never seen that in real life. I’ve always seen them go through with the palms of their hands. They also throw as much of their body weight into it as they can. It supposedly hurts like hell going through bricks no matter what, but they just ignore the pain. I have seen a few hands and arms broken while doing this, though. Not pretty, I might add.
This is just from an observational standpoint, so I could be way out in left field on this one.
Having done it you remember that forces travel in straight lines through solid things. If you hit the board ( I have never done stone) so that the force is sent through the middle, it shatters. But I am not a physics major… so I do not know the science details. It is a really cool feeling to get through them.
A timely question. The May issue of Discover has a story called “The Physics of Karate”. It basically boils down to transfer of force…when a black belt hits a slab of concrete, his fist touches the slab for fewer than five miliseconds. An average blackbelt chops at 46 feet per second, delivering a blow of 2800 newtons. Splitting a 1 1/2 inch slab takes only 1900 newtons.
Bottom line? It’s all in the technique, but the force bones can take vs. wood or concrete is amazing.
I had an instructor in Shorin-Ryu (sp?) Karate in college who had a soft spot for these sorts of demonstrations. He also was an advocate of what he called “calcitrants”. This is a buildup of scar tissue or hard cartilage or somesuch that he had developed along his knuckles and along the edge of his hand via impact-intensive training. Knuckle pushups, punching walls, hitting boards, etc. And damned if the guys hands weren’t like a leather bag of marbles. After a few months of such excersises (at a much lower intensity) I found that bare-fist impact was easier to deal with and much less painful. So on that level, you can toughen your extremities to deal with the impact.
Note that I am not advocating any of the above. If Glitch is still around, he can give you a much more informed answer.
There was an article on this in Scientific American back in April, 1979 entitled “The Physics of Karate”. One of the co-authors was Ron McNair, the black astronaut who went up on the shuttle Challenger. He had a black belt in Shot-kan. There was a more technical article by the same group in American Journal of Physics in 1982.
stolichnaya: Do you still do this? I’ve heard of guys who punch sand bags to improve this ability, and I’ve no doubt that it works. What I’m wondering is does it get less painful because:
- You get used to the pain
- The pads “protect” you (debatable in terms of actual damage
- You destroy some of the nerve endings in your knuckles
I can’t claim to know anything about nerve endings, but if the dentist can remove them an a few minutes, I would have thought that repeatedly beating the shit out of them should have an effect. Assuming that you haven’t done it for a few years, is it more painful when you restart?
Elementary Physics is all you need to know. Of course, they DON’T always make it through [those are some interesting faces to look at]. When you see a board being done, do you notice that the wood is cut with the grain? Can you imagine doing it against the grain? ha!
Breaks of the kinds that are described here involve more than simple f=ma.
Has anyone ever seen a “soft break?” That is when the karate-whiz in question lets his hand fall, slowly down, through a brick or piece of wood.
Of course, it’s not like he moves in slow motion, but there is an obvious lack of the sort of throat-twisting effort you would expect.
Those in the know ascribe this to “chi”… Who wants to explain that?
I’ve never seen the “soft break” that <b>sdimbert</b> is describing.
But I’ve done (and seen others do) the regular kind. Speed and focus is really the key (sorry if that sounds cheesy, but it’s true). You generally want to “pop” your strike, so that it transfers the energy to the target in as short a time as possible.
Here’s how to improve your chances of coming out unscathed:
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Hit the target and then recoil slightly. Maximum energy transfer and it leaves your hand/etc. on THIS side of the board, free from getting tangled in those messy splinters.
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Hit the target with a tougher part of your body. Obvious but true. The heel of your foot is better than your hand, the heel of your hand is better than your knuckles, the knuckles are better than the side of your hand, etc. And, as others have mentioned, you can toughen your knuckles/hand by doing knuckle push-ups (my sensei’s preferred method) or by hitting makiwara (traditionally, a big log that’s been wrapped with rope).
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Hit objects that break easily. Again, obvious but true. One board breaks more easily than two, wood breaks more easily than concrete, cinder slabs break more easily than real stone, etc. (never seen anyone actually break stone …). A good piece of wood to use is 3/4 in. plywood, roughly a foot square. Break WITH the grain (side of foot/side of hand/knuckles parallel with grain of wood). Almost anyone, trained or not, should be able to break such a piece of wood by hitting. The training keeps you from getting bloodied.
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Have someone competent hold the target. Really important. I saw an 8th-degree black belt who was visiting us from Okinawa break his hand because the people holding the wood flinched instead of holding it firmly in place. Of course, cinder blocks don’t need any human help.
The other question is WHY do karate folk break boards, etc.? -
To look cool, of course.
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It’s an easy way to assure that your punches/etc. really DO have good form, speed, and focus, and that you’re not just kidding yourself. If you finish with bloody knuckles, you know you need to practice some more.
handy,
Concrete, stone and ice are all things that Karate guys commonly break. None of these things have any sort of grain to cut with or against. There’s no trick here; it’s just the amazing ability to skillfully control the energy of one’s body.
I’ve broken boards before and it all comes down to technique and speed.
Most of the breaking stunts you see amount to gimmicks. It’s not much harder to break through two boards than one, IF you leave a gap between them and they are both oriented with the grain going the same way. The first board breaks, and transfers the energy from the initial impact to the second board, which also breaks. Etc. Some energy is lost in each board, but not all that much if you pick the right kind of boards.
The same is true for the guys who break X number of cinder blocks with one blow. If you are observant you’ll note that they ALWAYS have a gap between them. This allows the first block to transfer its energy to the second, etc. If you hit the first one with enough force, you’ll break them all.
The ‘trick’ is really nothing more than conditioning your hands or arm so that you don’t break bones, plus usage of the right technique to transfer energy from your body into your fist.
The biggest trick a karateka uses to develop a strong punch or kick is to transfer the momentum of the body into the arm or leg. A lot of this power comes from the hips. By twisting the hips, you cause the whole body to rotate. Then, by tensing up your muscles at exactly the right time, you can transfer the momentum from your body into your arm and fist. Bruce Lee’s famous 1-inch punch worked that way. He rapidly twisted his entire body, then let all the force be transferred to his fist. Those ‘soft’ punches you mentioned probably use this technique. I can put my hand on your chest and crack your ribs without taking my hand off. It’s still just the application of physics. A big wind-up of energy in the body, released into a tiny area in my palm. This no doubt also explains the belief in ‘chi’. If I put my hand over your heart and do this, there’s a chance I can stop it. But there’s nothing magical about it. Several hockey players have been killed in the last couple of years by taking a puck to the chest. I don’t think pucks have ‘chi’.
In comparison, a boxer’s punch relies primarily on the muscles in the arm to accelerate the fist. The energy delivered comes from from the mass of the arm times the velocity. By using the mass of the entire body, a skilled karateka can develop more power. Now it’s just a matter of making sure the object you are hitting doesn’t flex too much, is relatively easy to shatter, and that your bones are protected by enough tough skin or calluses to keep them from breaking.
Some martial arts breaking stunts are almost purely gimmicks. For example, the guys that put blocks of concrete on their body and have someone shatter it with a sledgehammer. The inertia of the heavy block transfers the energy slowly over a wide area, so even though it shatters the force on any part of the body is relatively low. Anyone with reasonably strong stomach muscles could do it.
Btw, most board breaks are done using relatively soft pine boards, held with the grain. These are amazingly easy to break. We used to let little kids break 1/2" boards with the heel of their hand to build their confidence. If the kid was especially small, the person holding the board could apply some torque with his hands so that the thing would break if you blew on it. In a demonstration once I accidentally snapped one that way, just holding it.
However, take two of the same boards, and put one with the grain perpendicular to the other, and it’ll become about 100X stronger. This is a classic composite structure, and it would take immense strength to break it.
toadspittle
Never seen anyone break stone? I’ll bet you a hundred bucks I could smash a stone with my fist using the secret techniques garnered in playground fights.
starts hunting around for a decent size thin piece of slate
This should have been mentioned before, but…the part of your hand/foot/head that you use to hit the board/stone/ice will GREATLY affect your chances of success and how badly you’ll injure yourself. Watch the next time a downward ‘chop’ is used to break something. The martial artist hits not with the hand, but with an area just in front of the wrist. Feel that area on your own hand. The bone in that area is extremely solid structurally, unlike those widely-spaced finger and palm bones, so your hand is much, much less likely to be damaged. A palm break uses the same area from a slightly different angle.
Combine the above with the amazing strength of bone, and breaking ain’t that hard. The compression strength of bone is greater than that of reinforced concrete, so, as long as your hit is straight and true (bone doesn’t torque well), you should be OK.
The thing about the objects broken is that they have low tensile strength, although they may have great compressive strength. Karatekas break pine boards cut with the grain “the wrong way”, or patio blocks (usually NOT cinder blocks) or even ice blocks. You can press down on any of these things and they can take a lot of weight, but if you support them on each end with no restraint – what’s called “simply supported” – and place a weight on the center they will all deform an eventually break, because they have n strength against being pulled apart. If you take high-speed movies or strobe photos you can see that the break begins at the lower surface (where the elements are under extreme tension), where it’s being pulled apart.
I’ve often seen karatekas break a stack of 1/2" to 1" boards that have been separated by pencils. It looks mressive, but it is elatively easy to do. You can also simply place the boards one atop the other, but then friction makes it a bit harder. Nonetheless, it is far easier to break hree one inch boards than one three-inch board. The force required goes up with the fourth power (I think) of the thickness.
With cement “patio blocks” the biggest problem is coupling energy from your fist or foot into the block, both because it is very massive (so you have to overcome inertia) and because it represents a stiffer “spring” than a piece of wood.
I’ve broken wood and cement, but never tried ice.
The important point here is that this is a little showy, but there is a point. It’s rue that you are holding the board or block in a way that exploits its weakness, but when you are up against an opponent you really are looking to do the same thing.
Sam Stone said:
“in comparison, a boxer’s punch relies primarily on the muscles in the arm to accelerate the fist.”
Not true. Perhaps we don’t use as much body torque as karate, but even a light jap properly executed will use rotation all the down to the hips.
As for breaking boards, it’s basically a trick. A whole lot goes into selecting the proper materials and positioning them so that they are breakable with a reasonable force.
Once that’s done, the main thing is not to hold back when you make the strike. WHen you break the boards (or whatever) most of the energy is transferred, and your hand or foot is left relatively unscathed. If you fail to break the object, then that object vibrates back delivering into your hand, basically beating the shit out of it. That’s what hurts.
I thought plywood was laminated and would not split easily parallel to the grain esp. a foot square 3/4 inch thick piece of the stuff. I would be mighty impressed if I saw a Karate Expert put his hand through a 3/4 inch piece of real plywood. Standard wood boards yes -plywood no. I think the karate expert’s hand would break before a 3/4 inch piece of plywood would split.
Plywood is a REALLY bad choice. Astro is right - plywood gets its strength from being several pieces of wood layered together in plys, with the grain of each ply 90 degrees from the other. Plywood is very hard to break with a punch.
The best material is soft pine, cut longitudinally so it has a long straight grain. Boards like this are almost trivially easy to snap.