Punch and Kick Force?

Discussion in 'General Martial Arts Talk' started by Kane, Jul 23, 2004.

  1. Kane

    Kane Black Belt

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    Does anyone know the average punch of a normal human and an average boxer/karate expert in PSI?

    Also what is the kick force of a normal human and a kickboxer/karate expert in PSI? I assume it is MUCH higher than the punch considering our legs are more than 3 times stronger than our arms.



    Thanks
     
  2. Kembudo-Kai Kempoka

    Kembudo-Kai Kempoka Senior Master

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    I don't remember the numbers, but I do remember working some adjusting (crack-backing) skills on strike plates to measure impule force. Several of us played with whacking the things, and oddly, punches typically registered higher PSI. We think it had to do with the speed of the bodypart at time of impact, and not as much to do with the weight of the part, or the depth of the force (legs bigger, take more energy to get moving, and hence press deeper into the target before dispersing their force?). We had guys there from different MA backgrounds, too. Was interesting. Fun to play with kime, getting immediate numerical feedback from minute changes in approach.

    D
     
  3. KenpoTex

    KenpoTex Senior Master

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    Another reason that punches might register higher would be that you're making contact with a weapon that has a smaller surface area...the ol' hammer and nail idea.
     
  4. Firona

    Firona Guest

    Exactly what I was thinking. A good thing to remember, because of this, is to strike only with your heal when you kick. That should get the old PSI up there.
     
  5. Chrono

    Chrono Guest

    Ok, I'm a little slow with this. What's PSI?
     
  6. WLMantisKid

    WLMantisKid Guest

    Pounds per Square Inch

    As in, per square inch of contact area, how many pounds of force are behind it.
     
  7. Chrono

    Chrono Guest

    Thanks. That's probably, like, the sixth time I've asked someone that. I can never seem to remember it.
     
  8. DeLamar.J

    DeLamar.J 3rd Black Belt

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    A vector is a straight line from point A to point B, such as the line your fist travels when moving from your hip to an opponent's chin. Any deviation from the straight line will result in a loss of power.

    Displacement is how far the fist is displaced from the hip to the chin along a vector.

    Distance is how far the fist actually travels during the punch, which includes any stray movements from the vector and its return travel back to the hip.

    Speed of the fist is measured using the distance it moves, which includes any extraneous movements away from the vector. Velocity is measured using displacement of the fist, which only uses travel along the vector and in only one direction.

    Velocity of the fist = displacement of the fist / time required to complete the displacement

    Acceleration of the fist = change in velocity of the fist / time required to achieve the final velocity.

    Force of the fist = mass of the fist (including arm and some of torso) x acceleration of the fist. As it applies to the punch, force is of no concern if it misses the chin. If it strikes the chin, then an important consideration is the amount of pressure the fist applies to the chin.

    Pressure of the punch = force of the fist / striking area of the fist. Thus the smaller the striking area of the fist, such as the first two knuckles versus the entire front of the fist, the greater striking force.

    Actually, the equation for force involves more than just mass and acceleration. The full equation is F=ma+cv+kx. This longer equation takes other variables into consideration, such as wind resistance, gravity, friction within joints, muscle tension, and energy lost through heat. This longer equation for force contains 6 parts: (mass x acceleration) + (velocity x displacement) + (damping x stiffness)

    Mass is basically the fist's weight.
    Acceleration is how quickly the fist increases in velocity.
    Velocity is how fast the fist is moving.
    Displacement is how far the fist moves.
    Damping accounts for force that is dissipated by flexible surfaces and structures contacting each other. Damping occurs when there is weakening in the structure of the punch. When the fist impacts the chin, skin, muscles, and joint collapse somewhat, which dampens, or reduces, the force of the punch. If the fist is covered in boxing glove, the striking force is reduced by dampening effect of the glove's padding. Some damping also occurs when the body oscillates. Since the body is mostly water, it oscillates when shaken by the reaction to the action of the punch. Damping is also caused by friction. Muscles generate heat by the friction of rubbing against each other, which uses up energy. Energy is also wasted by other types of friction, such as the arm rubbing against the body during a punch.
    Stiffness is how rigid the fist and arm are at impact. The stiffer the fist and arm are on impact, the greater the striking force. The hardness of the striking surface increases the force delivered because reaction force will not be absorbed, thus, the knuckles of the hand strike harder than the knife hand.
    Mass of the punch may be increased by using muscle tension to add the masses of the shoulder, torso, legs, and feet to the mass of the punching arm. Generally, speed decreases as effective mass increases, but, by using a sequential application of forces, such as arm, then shoulder, then hip snap, and then leg thrust, the fist is snapped out similar to a whip, without adding mass that may slow speed of the punch. Then, at moment of impact, the body tenses and adds the mass to the punch.

    Focus is when a full-power, full-speed technique is aimed to terminate a point in space. Focus is not just terminating the technique at the point in space, it is also a simultaneous contracting of all muscles to add all the power and mass of the body to the technique. Maximum power occurs when all muscles of the body contract at impact. Since the impact force of a technique equals the mass times the acceleration of the attacking weapon, to reach maximum force, you must be loose and relaxed as a technique starts and progresses so you may achieve maximum acceleration, and then contract all the muscles to achieve maximum mass. Since the technique stops at the point of focus, maximum force of the technique occurs at a point just millimeters before the point of focus. After maximum power point, the fist is decelerating. Without the contraction, maximum power is not reached, therefore, if an opponent moves into a technique that was intended to stop just short of contact, the attacker can lessen the force of the impact by not contracting into the technique. When sparring, the point of focus is just short of the surface of the chin, so the opponent is not harmed. In an actual attack, the focus point is internal of the chin, so that fist is at maximum velocity when if strikes the surface of the chin and thus strikes with maximum force.

    Taking all this into consideration, which punches harder, a large person or a small person? The large person has bigger muscles and more mass, but it requires more muscle power to move the greater mass so acceleration and velocity of the punch is reduced. The smaller person has smaller muscles and less mass, but the acceleration and velocity of the punch is greater. This, striking pressures of the two punches may actually be equal. The striking force of a speeding bullet and speeding locomotive may be equal, but which would you rather be hit by?

    A larger person has more reach, more mass to absorb blows, and more strength. The farther a punch travels, the more time it has to accelerate, so a larger person with longer arms may generate more power. However, it takes more time to cover the longer distance, which may give the smaller person time to avoid or block the punch. John Jerome, in his work The Sweet Spot in Time, states that large, muscular athletes are generally faster than smaller, thinner people when moving about. So, in general, a large person hits with more force than a small person.

    The momentum of an object is its mass multiplied by its velocity. By adding up the momentum of all individual objects in a system, the system's total momentum can be calculated. In a "closed" system, the net momentum never changes. This is a useful fact when analyzing an impact, because we know that the total momentum of the system will be the same after the impact as it was before the impact, even though the momentum of its parts may have changed. Momentum is a "vector" quantity, which means that two equal masses moving in opposite directions with the same velocity have zero net momentum.

    Energy takes many forms, such as the kinetic energy of a moving mass. Energy is a "scalar" quantity, which means that two equal masses moving at the same velocity have the same total kinetic energy, regardless of their direction of movement. The kinetic energy of an object is equal to half its mass times the square of its velocity.

    Energy, like momentum, is always conserved. But, sometimes it changes from kinetic energy, which is easily observed by measuring velocities and masses, to other forms that are harder to measure, most notably heat. The process of changing kinetic energy to heat is usually damaging to the material being heated. If the material is human tissue, it can be crushed, torn, or broken by the conversion of kinetic energy to heat. If the material is wood, it will break. A process that slowly or gradually converts kinetic energy to heat is usually called friction. A process that suddenly converts kinetic energy to heat is called an inelastic collision.

    Example 1: When billiard balls collide at normal speeds they suffer no measurable damage because their collisions are almost perfectly elastic. All collisions conserve momentum, but only elastic ones conserve kinetic energy. So, if one ball with a certain velocity strikes a stationary ball on-center, it will transfer all of it's momentum and kinetic energy to the stationary ball, stop, and cause the other ball to move away at the same velocity as the striking ball. If a perfectly elastic Taekwondo student struck a perfectly elastic target, the target would fly off undamaged, but with lots of kinetic energy, perhaps sustaining damage when it hits the floor.

    Example 2: If, instead of hard balls, we use balls made of soft clay, then, when one ball strikes a stationary ball, both balls will mush together and move away with half the velocity of the striking ball. The kinetic energy before the collision is MV2/2. The kinetic energy after the collision is MV2/4. Half of the kinetic energy has gone into damaging the balls. Since both balls are equally damaged, each ball got damaged in the amount MV2/8.

    Example 3: If a hard ball strikes a stationary clay ball, only the clay ball will be damaged. Therefore all of the lost kinetic energy MV2/4 went into damaging the clay ball.

    Example 4: If a clay ball strikes an anchored hard ball, all the momentum of the clay ball will be transferred to the earth, and all of its kinetic energy MV2/2 will be expended in damaging the clay ball. This is twice the damage of example 3, and four times the per-ball damage of example 2.

    So, as a Taekwondo student, you should be as elastic as possible as protection against damage. Proper focus unites the bones, muscles, tendons, and ligaments into a structure that is better able to distribute forces elastically (non-destructively), such as pre-stressed concrete does in buildings. It also means that an onrushing opponent who is impaled on a well-rooted reverse punch will sustain more damage than a stationary opponent. The effect of having a firm stance is most important when the opponent is stepping toward you, therefore, your best strategy for causing damage is to wait for the opponent to step toward you with an attack, deflect the attack, and then use a well-rooted reverse counter punch. Colliding elastically does not transfer any kinetic energy, so it should be be avoided. An inelastic collision with the target transfers kinetic energy that damages the target rather than your striking limb. You want your victim to be damaged, not pushed backward. To cause maximum damage to an opponent, targets should be chosen for their inability to respond elastically. The ability of a target to respond elastically depends on its structure, the speed of the impact, and the area of impact pressure.

    All tissues have a range of pressures over which they are capable of responding elastically. The transition from elastic response to inelastic response is called "yielding." As pressure builds in a collision between two objects, both objects are initially elastic. A striker strives to have a larger elastic domain than the target. Once the target yields, the pressure between the two objects stops increasing and starts decreasing. When we consider momentum rather than pressure, the speed at which your technique travels has a greater effect upon the collision than the mass of the technique. Therefore, maximize speed to maximize damage . If purpose of a technique is to break bone, then use a high velocity impact with a small target area. If purpose of a technique is to cause internal damage, then use a technique that will transfer momentum.
     
  9. Flatlander

    Flatlander Grandmaster

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    Excellent post. The true beauty of physics brings a tear to my eye.
     
  10. Chrono

    Chrono Guest

    Perhaps it may be a good idea for all serious martial artists to take physics.
     
  11. Kane

    Kane Black Belt

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    Good post DeLamar.J, but;

    what would be the force in PSI of a fighter's punch and kick?

    Afterward I wanted to ask what that would be in pounds pressure and how to convert.

    Thanks.
     
  12. DeLamar.J

    DeLamar.J 3rd Black Belt

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    You would need a machine to measure that. But you could probly figure out the average PSI of a person by there height and weight. But that still wouldnt be totaly accurate because someone with better technique can hit harder than someone two times there size.
     
  13. grb

    grb White Belt

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    I am interested to see these questions, as I have designed a piece of equipment (patent Pending) that can tell you. Basicly, I call it PunchO.. It would be fixed to a wall, A device of about 15" square, with a circular pad in the middle. When you punch the pad,, a digital display tells you the force in PSI. I would be interested in some feed back, ie: would people buy it ?
     
  14. jks9199

    jks9199 Cause of War & Destroyer of Civilization Staff Member

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    Well, since something very similar has been on the market for several years... It'd probably sell. But the question to me would be can you produce it and market it?

    Here's one: Herman Interactive Trainer
     
    Last edited: Jul 17, 2008
  15. kwaichang

    kwaichang Purple Belt

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    Remember Stallones movie with the Russian who could punch w/2000 psi?
    Well the DSC channel recently had an hour show dedicated to scientifically measuring all things in mixed martial arts; punching, kicking, etc.
    [​IMG] Chuck "The Iceman" Liddell was measured, straddling an opponent, with a 2400 psi punch.
    As for kicking, penetration was the important measure and again he penetrated about 41/2", more than a severe car crash.
    Hope this helps.
     
  16. kwaichang

    kwaichang Purple Belt

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    P.S. you only need about 15 psi in a kick to break a knee cap and most women can develop 80 psi for that.
     
  17. FearlessFreep

    FearlessFreep Senior Master

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    I've heard it only takes 4PSI upward to rip an ear off...
     
  18. kwaichang

    kwaichang Purple Belt

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    I really don't know but then people can and do continue a fight without an ear. It's much more difficult to sustain oneself without the use of a leg. :)
     
  19. TheOriginalName

    TheOriginalName Blue Belt

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    Some interesting discussion here.....

    As an engineer i'm relatively good at physics and it always blows my mind when you can look at a technique and break it down to understand the bodies motion and the physical principles.....

    When you get a chance go to Youtube and look up Fight Science (would post a link but can't access it from work - doh!!). Basically they take a heap of MAist and get them to do certain techniques on a crash test dummy - the results are amazing.

    And to those budding analysist out there - when it comes to any technique that involves rotation don't forget your circular motion stuff (particularly for looking at kicks).
     
  20. shihansmurf

    shihansmurf Black Belt

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    I measure my kicking and punching power in the agonized tears of my enemies :wink1: Heh, heh, heh...

    Seriously, interesting topic.

    I seem to remember a few years ago reading in Black Belt Magazine about these electronic devices that one could attach to a punching bag or makiwara. I don't recall ever hitting one but if they work, and frankly I'm not really sure what valid and measureable standard we can use for hitting power, given that neither PSI, newton meters, or joules are really applicable in isolation, it would be interesting to use as a developmental tool.

    Mark
     

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