Withstanding Impossible Forces
Perhaps the biggest misconception that people tend to get about martial artists is their ability to take punishment. I don't mean to keep picking on movies, but they really are the biggest perpetrator of these myths. There are fight scenes where the hero gets hit about a hundred times, but always gets up ready for more. The movies that are trying for that extra-authentic feel will even splurge with a bruise or two on the hero.
These kinds of movies really do perpetrate these myths, and it gets to the point where people no longer know what is real and what isn't. Sometimes, people hear about things that sound decently plausible that somehow parallel things they've heard. This is usually how myths get propagated; it just has to sound plausible. One such myth is about the martial artist who can withstand being pierced by a sword. Supposedly, his or her skin is impervious to the blade, and perhaps you have even seen videos on pseudo-documentaries where a similar trick is being performed.
Is such a feat possible? We know that repeated stresses against the skin can cause calluses. People that use their hands heavily for their everyday jobs will have rougher skin than those that push paper around all day. A person that performs martial arts regularly without shoes will certainly have a tougher layer of skin on their feet. Could it be feasible that there is some way to condition the skin so that a blade won't penetrate it? I could probably list some medical facts about the strength of the skin and compare it with callous and non-callous, but from a critical thinking perspective, I don't think that's necessary. Everyone knows just about how much the skin can take when confronted with a sharp metal object. Practically nothing. Calluses can help, but essentially it is like mustering a handful of pitchfork-wielding farmers to stand against a smart-bomb equipped stealth bomber. The knife will win, every time. If you have ever cut yourself with a really sharp knife, it takes almost no effort.
While conditioning can help, it is useful to look at the limits of leather as armor. Ancient warriors used leather if they couldn't afford metal or it wasn't available. Leather's primary defense was against slashing, not penetrating. The durability of leather could be enhanced by adding multiple layers, boiling it, or sewing in metal buttons. None of these options are available to the martial artist, or, more than likely, you in your everyday life. Most leather will be more durable than skin, and a slashing attack with a sharp blade would mean that the leather was cut and not your skin, but the armor was much more susceptible to a piecing attack. This was the biggest disadvantage of a leather bedecked ancient warrior. Although these warriors usually faced swords and spears, the leather breastplate was still used as late as World War II, where its main weakness was firearms. Leather can definitely be used as protection, but the myth requires penetration, and this is precisely the weakness of leather as armor. The toughest cowhide can be penetrated by a humble hobby knife. No amount of conditioning will make your skin as tough as cow hide, so just being tough won't cut it (pun indended.)
Just about anything organic has a distinct disadvantage when it tries to go up against steel. Some versions of the myth say it has something to do with the muscles under the skin. Super hard muscles act like armor, preventing the blade from cutting. Lay a piece of fabric over a steel plate and try to push the point of a knife into the metal. Theoretically, it wouldn't really cut the fabric because only the point would be touching the fabric. But muscle, even flexed, isn't going to stand against a sharp blade. A good knife can penetrate bone, so what chance does muscle have? What if the muscles are pliable? Relaxed muscles are less dense, and could give with the blade. This is one case where I would have to partially agree. The only way to prevent a blade from piercing is to prevent pressure from being applied. If by "giving" the myth means moving away, then yes that would help. This is really just getting around the problem, though, and not any kind of super power.
Well then, what about the guy you saw on a pseudo-documentary that was able to withstand a sword being pushed into his stomach without drawing any blood? I'm not going to say that this isn't an impressive trick, but I will say that it is a trick. First of all, you are meant to believe that the sword is razor sharp. I would be willing to bet that no proof of the point's sharpness was offered. Sometimes a piece of fruit is carved up as evidence, but an apple is perfectly easy to slice with a dull butter knife. Even then, the sharpness of the sword's blade implies that end is sharp, but it doesn't prove the end is sharp at all. An analogy would be to take an ordinary letter opener and a professional paring knife. Assuming you don't have an unusually sharp letter opening, it will probably have a pointy but dull ending. If so, then you should be able to take the letter opener and push it into your palm. It may hurt, but it will take noticeably more effort to break the skin than if you were to try that with the professional paring knife (practical experiments in this case are highly discouraged). This means that a blade's ability to cut is very dependent on the sharpness of the edge or point. I will discuss why in the Physics section, but for now, all you need to know is that it has to do with the force being applied and the area it is applied to.
How impressive this trick is depends on how sharp the sword is. Just because you see a demo of the sword's cutting ability, you shouldn't immediately conclude that the point is sharp. This kind of thing is a classic magician's trick. It doesn't mean, however, that the sword trick doesn't require skill. If you were overzealous with the letter opener, you could certainly cut yourself. The person doing this trick really needs to know what they are doing and how much they can take, and definitely when to give. You have to wonder, though, how willing they would be if you switched their sword with the professional paring knife (I have a very strong suspicion I know what the answer will be!).
So if not knives, then can a martial artist take a lot of blunt punishment and keep going? The short answer is yes, but not quite like the movies portray. How much damage a blow does to the human body is a function of many variables; the power of the blow, the hardness of the striking surface, the area striking surface, the size of the victim (i.e. mass), the location of the strike, the relative state of preparedness of the victim, the angle of the blow, the vulnerability of the target area, etc. Other less intrinsic properties, such as the person's relative physical fitness, their ability to take pain, their preparedness to receive damaging blows, their conditioning, etc. also contribute.
To know how much someone can take, let's construct a martial artist in the best possible way. A person that is in shape is less likely to suffer debilitating affects from a blow, so we'll start there. Not only are they less likely to be hurt, added muscle mass is basically blunt assault armor. Because muscles have pain nerves, they're not perfect, though. Someone with huge muscles is less likely to feel pain from a blow if only because the nerves are buried deeper underneath the skin, but the right blow can still cause lots of pain. The best way to prepare yourself to get hit is to, well, get hit. This is called conditioning, and it can happen in many different ways. Some forms of Karate condition the hands by preparing buckets of sand that the students thrust their hands into. After a while, the students move to new buckets with slightly larger rocks. Finally, the students thrust their hands into gravel. Thai kickboxers condition their shins by pounding them against wooden poles. What does this do? Repeatedly striking a single point to strengthen it does work. First, bones can become denser. This sort of thing is expensive for the body to do, and it won't unless it has to - just like building stronger muscles. By doing it over and over again, the body believes that you are doing something necessary for survival, and will try to accommodate it (if you back it up with the right resources - i.e. diet). Second, you can develop denser muscles that are less prone to shock damage, and this would be more the result of you flexing your muscles before the blow occurs (and in general, a flexed muscle is much better at taking a blow and preventing damage beyond the muscle itself). Third, you can develop calluses on the striking area (such as end of the fingers). Finally, and most importantly, you can destroy the nerves in the striking area.
That last one may be somewhat surprising, but it is exactly what happens when you condition a striking point. Pain nerves are there for a reason, to indicate that damage is occurring. By repeatedly smashing your knuckles into something, you are not only toughening up the cartilage of the knuckles (i.e. calluses), you are systematically deadening the pain nerves in the knuckles as well. This isn't necessarily a bad thing, as a martial artist presumably wants to be able to hit stuff without pain shooting through his or her knuckles on every blow. Extreme conditioning, as some martial art styles practice, is the process of turning the hand (or foot, or elbow...) into a hardened weapon. Theoretically, one of these warriors can break boards with their fingers or concrete with their knuckles. The cost is not only reduced feeling in their hands, but a loss of dexterity and coordination. Scary as that sounds, I'm not saying that a martial artist, especially one in a striking art, shouldn't condition himself or herself. There is a balance that must be struck against between toughness and damage. The hands may be popular things to condition, but other areas include shins, feet, forearms, knees, and elbows. I'm sure the practitioners of extreme conditioning can greatly extend this list. I've heard of conditioning to the neck and even groin. Conditioning does work, and it can give a martial artist an advantage, but there are limits.
Assuming our theoretical martial artist has gone to the extreme and conditioned themselves like no other, we now have an individual that can take punishment about as well as anyone could. How much damage could this person take in a real fight? Probably a decent amount. Hits to the arms, legs, or body would not necessarily cause that much damage against an opponent of lesser skill or size. Only a trained fighter could produce the power necessary to really cause damage to someone conditioned as well as this person (provisionally). The pain tolerance of our martial artist would theoretically make it such that he could be hit numerous times before getting affected. There's no real concrete way to calculate how many times he could be hit, but here are some of factors involved. Any force strong enough to break bone would render any amount of conditioning irrelevant (noting that how a bone breaks is depend on direction of the force in some cases). After all, bone is the hardest part of the human body, so if something can break bone is there anything else that can stand up to such a blow? The muscles add additional protection, but there are limits to this as well. It is possible to "take" a blow strong enough to break bone, but this involves yielding to it, not stopping it cold. If you watch a professional mixed-martial-arts fight, then you know that solid blows almost always have an affect on a fighter, and that most of the effort in defense is avoiding the blow, not blocking them. In movies, the martial artists are always taking direct shots to the face, body, back, stomach or other vital area. Any kind of weapons, including sticks, cars, brass knuckles, nun chukka, chairs, ladders, etc (the list of bad-guy movie weapons is astounding), is more than capable of generating forces beyond what any conditioned martial artist can take. They may be able to take more damage than your average person, but there is an upper bound on the force a martial artist can take. Worse still, the reality is that forces far less than bone breaking can be enough to put down our martial artist.
No matter how prepared, we all have inherent vulnerabilities. For example, the average five-year-old child has the power to badly hurt any adult. The most vulnerable part of the human body is the eyes. It takes a mere scratch on the surface of the eye to produce untold amounts of pain, and a child certainly has the power to do this. No one would expect a child to "beat up" an adult, but this illustrates the point that a blow in the right place doesn't have to be super-powerful to be effective. Consider the rules for most professional fights, and you realize that the places most vulnerable to damage are not valid targets. The eyes, the back of the head, the groin, and strikes to the throat are all illegal, and professional fighters generally do a pretty good job of avoiding them (the occasional low blow being the most common). This really does separate professional fights from a self-defense situation. Your average back alley brawl between two drunk idiots aside, a real fight has no rules. There are no illegal attacks, and it is both scary and reassuring to know that there are targets they can cause so much damage without needing sledgehammer power. For our theoretical martial artist, this isn't good. If he were fighting a large number of bad guys, also trained in martial arts, with the purpose of killing him, then they have a pretty good change of hurting him very quickly. While the human body is very resilient, it is not a punching bag. You can condition yourself to make your threshold higher, but you can't get around the human body's inherent limitations.
People are built different enough that it is almost impossible to predict how much damage he or she can take before succumbing, and where the blows occur is a highly important factor. Conditioning does come into play, but there are only so many places that can be conditioned. For instance, conditioning the head is not practical or even possible. Repeated blows to the head will accomplish nothing other than damage to the brain. It is also impractical to learn how to take a punch across the jaw, and repeated attempts at conditioning would probably make the condition worse, not better. (I won't go into an explanation, but it suffices to say that the jaw area is delicate and contains a lot of important stuff - teeth for instance. It just isn't a good idea to repeatedly smash this area!) Some people who have been professional boxers for a long time have shown signs of reduced mental capacity. This is caused by a lifetime of banging on the skull. It doesn't take a medical doctor to guess why this isn't good for the brain.
The best way to "block" a blow and continue fighting is to avoid it before it hits. In movies, the more blows that a martial artist takes the more implausible it is. Certainly, he or she can withstand quite a lot of damage, but even the best can't take more than a few well-placed punches without being knocked out. I can forgive withstanding punches and kicks to a degree, but some movies even go so far as to have the hero taking hits from weapons repeatedly. A weapon, like a stick, can cause a lot more damage than a punch. There are martial arts styles out there that specialize in breaking things such as two-by-four inch boards against their shins or arms, but these are highly conditioned strike areas, and the martial artist is prepared to take them. If a bad guy cracks that kind of board against the hero's skull, he will be hurt, no matter how conditioned he is. Even if a martial artist is conditioned to take strikes, taking a blow unprepared can be devastating (no "give", no protection of flexed muscles. Just cold hard nastiness). Instead of taking all those shots, or blocking them, the martial artist should simply get out of the way. It isn't easy to do, but avoiding strikes gives a martial artist a huge advantage over taking blows. There is a saying that goes something like this: A beginning student does not know how to block. The advanced student has mastered blocking. The Black Belt does not need to block.
- Microsoft Encarta, Boxing, Health and Safety: http://encarta.msn.com/encyclopedia_761571782_5/Boxing.html#p27, August 12, 2006