Regarding weight and force

[rojcewiczj]

I read recently that top sprinters can generate a force five times their body weight on one foot during their stride. This made me consider how the gravitational force acting downward on your body cause an equal reaction force acting upwards against your center of gravity. My question, or rather what I'd like to put up for discussion, is how important is this upwards/downward force to ones ability to exert force on objects external to ones self and the effect of external force acting against ones self? After all, if one pushes on a wall without any effort to maintain or increase the force acting on ones center (downward/upward force), then one pushes ones self away from the wall. Consider if one could create a force five times their body weight against the ground ( a scale would read you as becoming five times heavier!) and at the same time, while that upward force is five times what it is when your standing at ease, one extends ones hands into the wall in-front of ones self. How much does the force acting upwards against your center of gravity effect the force you can exert though your hands? It seems to me the issue is largely in the direction of the force. While the upward force may be tremendous, it cant be directed horizontally. Is the answer to be found in a diagonal line which leads from foot to hand? This question for me gets to the practical essence of martial arts.

Also, I read that a skilled boxer can throw a punch that generates 5,000 newtons of force, well over five times the amount of force acting upwards on my center of gravity when standing.
If that is true, how come elite boxers arent sending their opponents flying out of the ring when they punch them solidly?
I dont get it! How is it that 5,000 Newtons of force can be dissipated on contact when it comes to a punch, while 5,000 Newtons generated during dead lift would theoretically allow one to
lift over five time my body weight? It seems to me that the issue is tied to the role of ground-reaction force and how are bodies function within its context.

[Peacedog]

Generally speaking the force expands elastically via the fasciae in my experience.

Regarding the example of a boxer, you can increase the amount of force transmitted at a point of impact by practicing with a mechanical scale placed against a wall.

You do this by placing the scale against a wall and pressing into it by expanding the joints into the scale. This is different in effect than pushing against the scale.

With practice, about 5 one minute repetitions with at least a minute between repetition as rest, you will gradually be able to increase the amount of force transmitted. Practice 3 times per week. Initially, this will be about 25% of bodyweight as registered on the scale. With practice you can eventually generate your full bodyweight. It takes approximately 6 months to a year to do this.



Maintaining the ability take about one session per week.

[zrm]

That's an interesting exercise. I do a similar one except put the scale on the ground, step on the scale, and push horizontally into the wall and to register a downward force on the scale. To get the greatest effect you need to create a force line from fist to foot and relax the muscles in the right spots. I will try placing the scale on the wall next time.

[dspyrido]

Also, I read that a skilled boxer can throw a punch that generates 5,000 newtons of force, well over five times the amount of force acting upwards on my center of gravity when standing.
If that is true, how come elite boxers arent sending their opponents flying out of the ring when they punch them solidly?
I dont get it! How is it that 5,000 Newtons of force can be dissipated on contact when it comes to a punch, while 5,000 Newtons generated during dead lift would theoretically allow one to
lift over five time my body weight? It seems to me that the issue is tied to the role of ground-reaction force and how are bodies function within its context.

You need to consider impulse and vectors (in newtonian physics force does not measure direction). The duration of any short impulse strike (like a jab, cross, fire in hsing-i) is that it changes direction (impact point goes back) and penetrates for a short time. The result is that it is behaving closer to a compression wave than to a collision calculation.

There is also a dependency on the type of measuring equipment being applied. If the impact is measuring pressure (not impulse) using a measure of Newtonians then a pushing cross style punch will measure higher than the way most good strikers will hit. Psychologically if told to hit a meter they will measure up, stand their and hit. If they are fighting then they will cover, hit, move, move, cover etc. and therefore the impact duration (impulse) will be shorter.

So the better way to analyse this sort of hit is a wave. In waves mass does not move as much as a collision and has other tendencies. As a result there will be less opponents being knocked out of the ring but a lot more getting hit and falling down.

That does not remove the ability to apply longer contact strikes (like in wood for hsing-i) but these are a different beast, are trained differently and unless you are trying smash the opponent right out they are not the best tactics to deploy when you are sports fighting. Knock out or not if you get the points you win. If you don't then you loose. Just ask pacqui.

[Peacedog]

ZRM,

I'll give the floor based exercise a try as well. Frankly the thought never occurred to me to do it that.

And yeah, the line of force thing is what you want to do in this context. I've found visualizing pushing the joints fully open by leading the line of force from the ground out to the finger tips helps as well.

Peacedog

[I-mon]

Cool exercises guys. I agree that this is fundamental to martial arts. In fact, it's fundamental biomechanics. In the case of sprinters, they are able to produce huge forces because of the strength and elasticity of the tendons, especially the achilles.

In all MA, but especially IMA, a huge part of what we're training is producing forces against the ground, which transmit equal and opposite forces through our bodies, moving them through space and/or transmitting those forces into our opponents.

So, in all IMA type exercises, it's worth (IMO, IME, FWIW, etc) spending a while practicing with focus on the forces of the feet pressing into the ground to move the body, rather than on the arms. It's still whole body power, but you're trying to push-pull on the ground with the whole body.

Starting with simple planes of motion, adding complexity. IMA 101.

It's the exact principle I'm trying to illustrate in those vids I made a while back (note, I have deliberately generalized these movements so that they are not overtly "martial" in any way):

[zrm]

I also practice a similar set of exercises to yours I-Mon.

[rojcewiczj]

It seems to me that until one is in command of their vertical power (downward/upward force made possible by gravity) and in command to the extent that they can willingly increase and direct that force in response to forces imposed by external objects, until that point, all talk of power is pointless. To be full of returning force, returning from the ground in response to force generated downwards seems, in practical speak, to be the very definition of being "powerful".

[Bhassler]

I think there was a rather long and heated discussion of this before (specifically about vectors), but force does include direction. F=MA. Direction is implicit in acceleration. The term "vector" is really more of a mathematical term than a physics term. That said, a wave may be a better model for calculating force in MA than simple linear calculation, I have no idea.

Also, it's less important how the force is generated than how it's delivered. I don't have the exact reference, but I recall reading that walking down stairs can typically generate up to 3 times your body weight on your calf muscles, which would mean that even a not very fit 100 lb weakling could manage 300 lbs of force with no special coordination or training. Going back to F=MA, the force applied by a technique would be figured by the amount of time it takes the striking surface to decelerate-- as long as it landed, how long it took to come up to speed is irrelevant. That's why 10 lbs of steel dropped on one's foot hurts more than 10 lbs of pillows-- the softness of the pillows means it takes more time for that 10 lbs to go from motion to rest.

Tying all of that back to verticality, we already have power, but delivering it effectively requires plugging all the places where power is leaking out via inefficient body mechanics, and having an efficient system relative to gravity is pre-requisite to efficiency relative to gravity plus additional external forces. That's my theory, anyways, but I'm just a tired dude typing on the internets.

[KEND]

While researching the relative energies of various types of punches some years ago I came up with the following
Karate punch[flexing bicep, twisting hip] 73.76 ft lbs[Wilk, McNair, Feld and Walker]
Whipping power:37.8 ft lbs[from Myrhvold amd Currie]
Fajing shockwave power: 21.6[my own calculations]
As can be seen the fajing is much lower but can be focused using a specific hand configuration and directed at internal organ.
The use of a gravity fueled vertical force requires complete 'dead weight' relaxation of the body for shock power. This can be turned into vertically upward power by bouncing the power, where the legs are flexed rather than bent

[Bao]

Good thread.

it's less important how the force is generated than how it's delivered.

+1 Perfectly so (IMHO).

the force applied by a technique would be figured by the amount of time it takes the striking surface to decelerate-- as long as it landed, how long it took to come up to speed is irrelevant.

Well expressed. I have very much the same feeling. I would say that it's when you collide with or penetrate the target when everything must match. I also feel that traditional martial artists prepare too much, or focus too much on preparation. Whole body power is great, but if you start and build up power long before your fist have met the surface, your best force might already be gone when you hit your opponent. And if you "wind up and release", you must release when your fist meet and penetrate the surface, not one second earlier. Then, again, your best force will be gone. This is why "one inch" or no distance punching can be very powerful when the timing is good, when everything match together on a fraction of a second. This is also why much of what is seen in shaking solo fajing exhibitions does not work very well on an opponent. It might hurt, but a lot of it won't do any damage, because how it's demonstrated, the "fa" or release of jin/energy happens before the physical contact with the opponent.

Karate punch[flexing bicep, twisting hip] 73.76 ft lbs[Wilk, McNair, Feld and Walker]
...
Fajing shockwave power: 21.6[my own calculations]
As can be seen the fajing is much lower but can be focused using a specific hand configuration and directed at internal organ.

Do you think that you have those 73.76 lbs when you do a Karate punch?
For "shock fajin", where was the timing when you released and when you did hit a surface? The distance? Far or close?
Why should a shock fajin be better directed at a n internal organ than the Karate punch?

[KEND]

The karate punch energy is spread over the surface of the knuckles impacting the body. The resilience of the fascia will absorb and spread the energy but there will be some compression and damage probably extensive bruising and some penetration , possible bone fracture[in rib area]The fajin is delivered after first compressing the surface of the fascia to provide a path for the shock wave. The hand is shaped to give a specific waveform directed at a particular organ. The figure given applies to pao chuan which produces a convex wavefront directed at the heart, imparting energy and momentum to the organ

[Bhassler]

You can take the slack out of your opponent's system whether you use fajin or not. Fajin might provide an additional option for how to accomplish that (maybe or maybe not), but to say that other types of strikes (or systems) don't use the same principle is not true.

[Bao]

The karate punch energy is spread over the surface of the knuckles impacting the body. The resilience of the fascia will absorb and spread the energy but there will be some compression and damage probably extensive bruising and some penetration , possible bone fracture[in rib area]The fajin is delivered after first compressing the surface of the fascia to provide a path for the shock wave. The hand is shaped to give a specific waveform directed at a particular organ. The figure given applies to pao chuan which produces a convex wavefront directed at the heart, imparting energy and momentum to the organ

Well.... A good paoquan should be able to break bones as well ... IME at least...

[KEND]

The above is based on several decades of training, experimentation with many students, research into the physics and mechanics of strikes..also.teaching so other people can do the same thing, Other strikes, for example the very tight whipping action can have a similar but not exactly the same effect , Pao chuan may break bones but that is not the objective there should be little external evidence of a strike. The internal strike needs little wind up and can be used by smaller people and seniors with the same effect
Comparing with 'external ' strikes is like comparing apples and oranges, its not a pissing contest, take it or leave it