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Physics and Karate

Page history last edited by Dan Hausel 11 years, 3 months ago


Karate is well-known for its amazing focus and incredible power that sometimes results in feats that almost defy explanation. Take for instance, the late Grandmaster Gogen Yamaguchi who killed a tiger with his bare hands during the early part of the 20th century, while he was held captive my the Chinese. There is also the well-documented demonstrations by the late Grandmaster Masutatsu Oyama, who fought several bulls with his bare hands, knocking off horns with a shuto (bare hand strike) and killing three with a punch to the skull in the 1950s. One of these battles was recorded in photographs in his classic book, What is Karate? Other amazing feats have been performed by Grandmaster Rod Sacharnoski and his students –who take full force strikes and kicks to the throat, soloplexis, ribs and groin with no effect whatsoever. How can we explain these feats through science?   




Tameshiwara - UW Students learn a little about karate, physics and even a little geology at rock breaking class.


Using science to analyze martial arts is something I hope to incorporate into a martial arts training center (hombu) some day. This center would represent a plethora of traditional martial arts centered around Seiyo Shorin-Ryu karate and kobudo and be open to other disciplines such as jujutsu, iado, aikido, traditional judo, kyudo, ninjutsu, etc.; include a hall of fame and museum dedicated to traditional martial arts; a meditation and tai chi classroom where one can retire to meditate and train in related activities including tea ceremony (chaji), aerobics, tai chi, etc; and include a certifying board for martial arts instructors around the world.


My so-called ‘dream’ hombu science center would have the ability to measure one’s focus and power and analyze techniques using striking surfaces that enclose accelerometers and employ high-speed video cameras to record velocity, acceleration, and balance. This facility would enable a person to reach full potential in less time than conventional training methods, and would have potential to develop karateka into powerful (physically and mentally) martial artists.


It turns out that National Geographic may have tapped into my dreams without my knowledge (lol). A recent program aired by NG used scientific methods to measure extraordinary focus by some martial artists. The program (Fight Science) was able to demonstrate that some martial artists have the ability to strike 4 times faster than a snake, generate forces 3 times greater than a sledgehammer, and generate velocities 2 times faster than a blink of an eye!


It was shown that a well-trained martial artist can generate >1000 G’s of acceleration with a tsuki (punch) or empi (elbow) uchi (strike). This is equivalent to >2000 lbs of force. To put this into more visual terms, NG reported that this is essentially equal to some forces generated in a 35 mph auto collision! Thus, when such techniques are completed with proper technique and focus, one can generate enough force to break a 4 to 5 foot stack of bricks with their bare fist or elbow, and do other superhuman feats, such as kill a bull with a tsuki as demonstrated by the late Mas Oyama.


Have you ever wondered what kind of force would be necessary to break a rock with a bare hand (shuto), a brick with bare knuckles or a rock or board with your head. What would it take to break a horn off a living bull with a shuto (which was demonstrated by the late Mas Oyama, Soke)? Or more importantly, how can a much smaller person defeat a person twice his/hers size?


Florin Diacu discusses the forces of a traditional karate punch in an article entitled “On the Dynamics of Karate” and answers some of these questions and provides some very interesting concepts supported by physics that I would like to review. According to Diacu, the energy generated by a punch (zuki) is best examined using the following:

ET = EP + EK + ER

Total energy = potential energy + kinetic energy + rotational energy


Which can be written as: E=mgh + 0.5mv2 + 0.5mr2w2


This formula considers potential energy, kinetic energy and rotational energy generated by a zuki. Here, m is the mass used in a punch, g is the gravitational constant {32 feet/second2 (9.8 m/s2)}, h is the difference in height from the initial position to a position where the zuki strikes its target {when stepping forward the body may drop 6 to 8 inches (15 to 20 cm) while delivering a punch according to Diacu}, v is the velocity of the fist, r is the radius of the fist, and w is the angular velocity of the fist’s rotation (something that is uniquely characteristic of a karate punch).


First, it should be obvious that the larger the person, the more powerful the punch as long as all other factors are the same (which they of course are not). Thus, (1) the greater the mass, the greater the energy (energy increases linearly with mass).


So let’s take a karate-ka by the name of Toshio. If Toshio is twice as heavy as another karate-ka by the name of Miagi, then Toshio has the potential to produce twice the amount of energy as Miagi based on this single variable.

However, we do not put all of our mass into a punch, and the mass of the punch may better be represented by the mass of one’s arm. Since a typical arm is only about 10% of our body weight, this dramatically decreases the amount of mass used in a punch (this is a simplification – because when we use a proper rooted stance to the floor or ground, or move forward using much of our body weight in a punch, this will also increase the energy of a punch). Even so, lets just consider the arm as the only mass that is involved in a punch. So if Toshio weighs 155 pounds and Miagi weighs 100 pounds, then Miagi must punch only 18% faster to achieve the same force as Miagi (if all other factors are the same). This is not a great amount considering such a great difference in body weight. A karate ka learns through proper technique to get more mass into a punch with proper hip rotation as well as by moving his/hers body forward with the punch.


(2) The lower the drop, the greater the energy, by remaining at the same height (h) when punching will result in energy conservation. This is one reason why we work hard in karate to keep our shoulders at the same height while stepping forward. This relates to the first part of the formula, which considers potential energy, which is a substantial source of energy since it considers the entire mass of the body.


(3) The greater the velocity, the greater the energy. The greater the velocity of the fist, the greater the amount of energy generated. This is very important in that velocity quadratically influences energy (by a factor of four)! This means that if Toshio and Miagi have the same mass and Toshio’s punch is twice as fast as Miagi’s, then Toshio can produce 4 times more energy with his/her punch! This is one of several reasons why karate punches and kicks are so effective. When breaking rocks and boards, maximum velocity is achieved at the point of impact producing maximum force. Based on high-speed movies taken of black belts at Cleveland State University the average speed of their punches was about 23 feet/s (7m/s).


(4) The effect of fist rotation is negligible. The effect of fist rotation is negligible in increasing the overall energy of a punch according to Diacu. This is not surprising as the purpose of the rotation is primarily for efficiency of punching and for linear movement in order to obtain the greatest possible velocity over the shortest amount of distance.


To show the effects of fist rotation (rotational energy), Diacu describes a person weighing 155 pounds. This black belt will have arm weight of 15.5 pounds, an average punching speed of 23 feet/second at the point of impact, a fist rotation of 5 π rad/second (the fist rotates 180O in 0.2 seconds), a fist radius of 1.2 inches, and a drop in height of about 7.9 inches which will result in


EP (Potential Energy) = 137.2 J (joule; 1 J=0.239 calories) {100 ft-pounds}

EK = 171.5 J {130 foot-pounds}

ER= 0.78 J {0.58 foot-pounds}

ET=309.48 J {228.3 foot-pounds}


This shows that rotational energy accounts for only 0.25% (one-quarter of a percentage point) of the total energy – a very small amount!


(5) The greater the distance, the greater the time. This should be obvious that it takes more time to travel a greater distance. This implies that a person’s punch can reach its target faster than a kick due to the shorter distance that it needs to travel. However, kicks can generate more power. The leg, which is longer than the arm, has more mass and a little more time to accelerate. A leg may weigh as much as 20% of the body mass.


According to Diacu, a typical black belt’s zuki may have a velocity of 18.7 to 32.5 feet/second (5.7 - 9.9 m/s), whereas a typical mae geri may have a velocity of 32.5 to 47.2 feet/second (9.9 - 14.4 m/s), a shuto 32.8 to 45.9 feet/second (10 - 14 m/s), maewashigeri 31.2 to 36.1 feet/second (9.5 - 11 m/s), and ushirogeri about 34.8 to 39.4 feet/second (10.6 - 12 m/s).


(6) Kicks may generate more energy than a punch For a person of 155 pounds (70 kg) may generate as much as 228.3 foot-pounds of total energy with a punch. But how much can this person generate with a kick?


Assuming a leg may be 20% of the total body weight. Thus for a 155 pound person, a leg is about 30.9 pounds (14 kg) and a good kick may have a velocity of 39.4 feet (12m/s). Thus the kinetic energy of the kick alone is 743.5 foot-pounds (1008J). This is more than 4 times the kinetic energy of a punch by the same black belt.


Conclusions. So why don’t we use more kicks than punches? The distance is shorter to the target using a punch, kicks are also more difficult to sight on a target, they are easier to avoid, and if properly done, some punches can generate a tremendous amount of knockdown power when done correctly with the right amount of snap, focus, hip rotation, and balance. If some upcoming issues of the newsletter, I will discuss some other facts of karate and physics.



My Secret for Karate - FOCUS

Over the years, I've received many compliments concerning my power and focus in karate. One of the greatest compliments was made by a very close friend of mine, Ron Smith, 8th dan who is also a member of Juko Kai International. At my first JKI clinic when I tested for Godan in front of Dai Soke R. Sacharnoski, Ron later told me that all member of the Florida clinic stopped to watch my incredible power. In the following year, he emphasized to others that the building litterally shook from the power of my strikes and blocks. This kind of power can only be developed through the focus of ALL strikes, kicks, and blocks and constant practice with this kind of power and determination.


All students of Seiyo Shorin-Ryu Karate must keep this in mind - this is what Shorin-Ryu is about and Seiyo Shorin-Ryu in particular practices and emphasizes focus on every and all techniques to the point that one should develop extreme power in all KICKS, BLOCKS, STRIKES, THROWS, ETC. EVERY technique in every kata - needs focus, focus, focus. This is why this art has become one of the more powerful arts in the world, this is why our students learn to develop one-punch knockouts.


If there is one thing I can say to help your technique - it is "focus, focus, focus!"  Opps, guess that was three things.


Soke Hausel



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