Punch retraction

Discussion on the three big Chinese internals, Yiquan, Bajiquan, Piguazhang and other similar styles.

Re: Punch retraction

Postby marvin8 on Wed Oct 21, 2020 11:59 am

suckinlhbf wrote:
I still think of it more as a rebounding pulse.

Front leg stops together with the body goes down will lead the rear leg to press on the ground. It will induce a rebound. The hip will open at the same time of dropping to create the structure for the rear leg onto the ground. Another old saying to help is "push the knee forward" at the time of dropping. It is a rebounding pulse.

In the Chen Xiang video, I see hand coordinates with foot. When lead foot lands, the hand stops, no rebound. It's the same in xingyi.

As the video says, Chen Xiang retracts his punch, not rebounds:

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Re: Punch retraction

Postby suckinlhbf on Wed Oct 21, 2020 12:58 pm

When lead foot lands, the hand stops, no rebound

If the body is straighter, it will be more balance. The rebound will be more obvious. Another old say is "Head Up".
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Re: Punch retraction

Postby LaoDan on Wed Oct 21, 2020 1:55 pm

marvin8 wrote:"Rebound" is not the correct word because there is no bouncing. In the rear straight as the toe-heel lands, weight is transferred to the lead leg, waist rotates, then shoulders, then the punch is issued.

I agree with the hand and foot coordination, and the FIST not rebounding; what I was looking at was the energy between the foot and the ground (in the Bajiquan video they refer to a “ground reaction force”). The earth is too massive for it to move significantly; so that force (~3x the body mass) impacting the ground must be conserved somewhere else (the loss to heat from the impact would also be relatively small). To me it rebounds from the ground back up the LEG, and then through the body to the fist, therefore hypothetically adding power to the strike.

I also do not think of this as “pushing off” of the floor (one is not trying to push their torso away from the floor when doing this type of movement), and the videos do not show a significant rise in the level of the head for either stationary or moving fajin strikes. I agree that there is no “bouncing” seen in the torso.

I am open to having some different and clearer terminology for this, but for now using rebounding pulse (a brief reaction force from the ground travelling back up the leg) is the best that I can come up with. What terminology is used for this type of leg to ground and back through the leg force when describing this in XYQ terminology? What would describe what is hapening to the conserved energy after the foot impacts the ground?

The motion capture along with the force plate on the floor seems like a good methodological approach to studying this. I would like to see a comparable analysis of a stationary strike to see if the force into the ground increases significantly (though likely less than when stepping). I learned this type of striking while simultaneously stepping from the Chen style fajin form (as well as the minimal Xingyiquan that I have learned, etc.), but I suspect that the force into the ground also increases (> body mass) during stationary fajin movements.
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Re: Punch retraction

Postby marvin8 on Wed Oct 21, 2020 3:34 pm

LaoDan wrote:
marvin8 wrote:"Rebound" is not the correct word because there is no bouncing. In the rear straight as the toe-heel lands, weight is transferred to the lead leg, waist rotates, then shoulders, then the punch is issued.

I agree with the hand and foot coordination, and the FIST not rebounding; what I was looking at was the energy between the foot and the ground (in the Bajiquan video they refer to a “ground reaction force”). The earth is too massive for it to move significantly; so that force (~3x the body mass) impacting the ground must be conserved somewhere else (the loss to heat from the impact would also be relatively small). To me it rebounds from the ground back up the LEG, and then through the body to the fist, therefore hypothetically adding power to the strike.

I and the study do too. We are not talking about fist, but the rear foot. The only "ground reaction force" referred to is the initial rear foot pushing off the ground:

Stanford.edu wrote:First we found that master Chen applies to the ground a force of 2200 Newtons, and a torque of 11,000 Newton/meters when he strikes, precisely when his hand reaches maximum velocity. We hypothesize that he may be pushing off or pivoting from the ground into the object.
marvin8 wrote:In the baji punch clip, Adam Hsu generates power by pushing off the rear foot creating ground reaction force, torque of shoulder and hips (90° recoil), falling step (momentum), weight transfer and chambering of fist.


LaoDan wrote:I also do not think of this as “pushing off” of the floor (one is not trying to push their torso away from the floor when doing this type of movement), and the videos do not show a significant rise in the level of the head for either stationary or moving fajin strikes. I agree that there is no “bouncing” seen in the torso.

I am open to having some different and clearer terminology for this, but for now using rebounding pulse (a brief reaction force from the ground travelling back up the leg) is the best that I can come up with. What terminology is used for this type of leg to ground and back through the leg force when describing this in XYQ terminology? What would describe what is hapening to the conserved energy after the foot impacts the ground?

After the power and punch is finished, Chen Xiang retracts his punch or completes a contraction-relaxation contraction cycle and does not move his foot.

LaoDan wrote:The motion capture along with the force plate on the floor seems like a good methodological approach to studying this. I would like to see a comparable analysis of a stationary strike to see if the force into the ground increases significantly (though likely less than when stepping). I learned this type of striking while simultaneously stepping from the Chen style fajin form (as well as the minimal Xingyiquan that I have learned, etc.), but I suspect that the force into the ground also increases (> body mass) during stationary fajin movements.

I believe you are misunderstanding or misinterpreting the study regarding "ground reaction force." Chen Xiang does not move his foot once the punch lands. He only retracts his punch.
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Re: Punch retraction

Postby suckinlhbf on Thu Oct 22, 2020 8:29 am

having some different and clearer terminology

Chinese literatures said "混元一气吾道成". The word Hun Yuan "混元一气" does not give a clearer explanation and is not a clearer terminology. It is the goal for training but is opened to different interpretations. Once get on to its path, different kinds of powers come out including the rebound pulse. It would be preferable to train for the destined goal (the trunk of a tree than its branches) from the training prospective. Agenda for the academic researchers may not be the same.
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Re: Punch retraction

Postby LaoDan on Thu Oct 22, 2020 8:32 am

marvin8 wrote:We are not talking about fist, but the rear foot. The only "ground reaction force" referred to is the initial rear foot pushing off the ground:

The force plate on the floor in the bajiquan video study is measuring the forward leg, not the rear leg (or am I missing something?). It appears like the 3x body mass force that is mentioned is from the front foot landing rather than the rear foot pushing off.
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Re: Punch retraction

Postby suckinlhbf on Thu Oct 22, 2020 8:49 am

The initial rear foot pushing off the ground is the kinetic mechanism whereas when the forward leg and rear leg land on the ground is the rebound pulse mechanism. Fist power is the combination.
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Re: Punch retraction

Postby marvin8 on Thu Oct 22, 2020 10:29 am

LaoDan wrote:
marvin8 wrote:We are not talking about fist, but the rear foot. The only "ground reaction force" referred to is the initial rear foot pushing off the ground:

The force plate on the floor in the bajiquan video study is measuring the forward leg, not the rear leg (or am I missing something?). It appears like the 3x body mass force that is mentioned is from the front foot landing rather than the rear foot pushing off.

The study measures both back and front foot ground force: ground reaction force of rear foot, "applies to the ground a force of 2200 Newtons" and front foot landing, "3x body weight."

It is the timing of torque as the front foot lands that contributes to power. There is no front foot "rebound" or bouncing before fist makes contact, only landing.
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Re: Punch retraction

Postby LaoDan on Thu Oct 22, 2020 1:51 pm

The researchers only show vectors of force from the front foot. While they may have also collected data from the rear foot, it is not shown in the video. I take the shaded square in the drawn version to indicate the force plate, which is only under the front foot of the ball and stick illustration. I do not see any force plate indicated for the rear foot. While they do use the terminology of pushing off, I think they are trying to describe the energy from the front foot rather than the push off with the rear foot. I think that pushing off of the front foot is a potentially misleading use of the terminology (e.g., as pointed out earlier, the torso is not raising up significantly = no bounce and no pushing off; also "pushing off" is mopre commonly used to describe the action of the rear foot). The force is being driven DOWN into the floor/force plate by the front foot. The motion capture DOES get angular velocities for both the front and rear feet, but the force plate on the floor only appears to be measuring the front foot. As stated, it is not entirely clear what is causing their observation: “we found that master Chen applies to the ground a force of 2200 Newtons,” but I still think that they are referring to the front foot.
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Re: Punch retraction

Postby wayne hansen on Fri Oct 23, 2020 1:20 am

Every time I see science looking into martial arts I am always surprised how unscientific they are
Don't put power into the form let it naturally arise from the form
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Re: Punch retraction

Postby marvin8 on Fri Oct 23, 2020 8:17 am

LaoDan wrote:The researchers only show vectors of force from the front foot. While they may have also collected data from the rear foot, it is not shown in the video. I take the shaded square in the drawn version to indicate the force plate, which is only under the front foot of the ball and stick illustration. I do not see any force plate indicated for the rear foot.

After further review yes, it looks like only one force plate. All similar studies I seen measure both front and rear feet and usually use two force plates.

LaoDan wrote:While they do use the terminology of pushing off, I think they are trying to describe the energy from the front foot rather than the push off with the rear foot. I think that pushing off of the front foot is a potentially misleading use of the terminology (e.g., as pointed out earlier, the torso is not raising up significantly = no bounce and no pushing off; also "pushing off" is mopre commonly used to describe the action of the rear foot). The force is being driven DOWN into the floor/force plate by the front foot.

Chen starts in orthodox stance with left arm raised, rear foot pointing forward and bending over. He pushes off the rear foot, torques his body, turns his front foot to a 45 degree, straightens his back, then lands. Once the foot lands, issuing of fist is finished, then retracted. The front foot does not move, pivot, bounce or push off.

Excerpt from "Tai chi master studied for power to control body:"

Jessica Rose, PhD, assistant professor of orthopedic surgery, on May 7, 2008 wrote:"It seems to be an almost perfect example of translating the angular momentum of his body into the linear momentum of the strike," said Rose. "The power begins first in the trailing foot and is then rotated through the body in a super-fast pivot, then transferred to the striking arm."


The video did a subpar job in explaining Chen's movements. When measuring striking power, a study should measure the strike at impact, not only ground reaction force when front foot lands. Chen could be leaking power into the ground. In the rear straight, the front leg is used as a pivot point before rotation and punch is completed.
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Re: Punch retraction

Postby Yeung on Sat Oct 24, 2020 10:13 am

wayne hansen wrote:Every time I see science looking into martial arts I am always surprised how unscientific they are

There are lots of problems between arts and sciences, and the Institute of Martial Arts and Sciences base in Greater Manchester, UK, is trying to explain some of the skills developed in martial arts in terms of sciences. Thousands of research articles on Taijiquan fail because they do not have a workable research variable. The research variable of this post is stored elastic energy. There are sufficient information on high intensified concentric muscle contractions do not produce stored elastic energy or recoil to facilitate retraction. And there are confirmations that rotational stretch do produce recoil. The discussion in this post is very fruitful on the differences between coordination and connection. The whip cracking illustration is an example of the utilization of recoil from one crack to another. Whip cracking provided a standard to produce a crack with the shortest possible whip length, as the length increase will require greater strength along the kinetic chain of the body such as shoulder, back and legs, etc. There are lots of examples from martial arts as well. Martial arts is much more complicate compare to one strike sport. Please continue to contribute your ideas and experiences for the advancement of martial arts and sciences.
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Re: Punch retraction

Postby wayne hansen on Sat Oct 24, 2020 11:45 am

The problem with the whip crack it is Kime
One point in space,if the point moves it is of little use
This is the opposite of circular internal arts
They are like the broadsword not the foil
Power is of little use if timing and yielding are replaced with the quest for power
I have finished fights with what felt like powerless moves
How many boxers talk about how they knocked out opponents with soft strikes
The bazooka works but in the phone box I would prefer a knife as dan would often say
Don't put power into the form let it naturally arise from the form
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Re: Punch retraction

Postby Yeung on Sat Oct 24, 2020 3:13 pm

wayne hansen wrote:The problem with the whip crack it is Kime
One point in space,if the point moves it is of little use
This is the opposite of circular internal arts
They are like the broadsword not the foil
Power is of little use if timing and yielding are replaced with the quest for power
I have finished fights with what felt like powerless moves
How many boxers talk about how they knocked out opponents with soft strikes
The bazooka works but in the phone box I would prefer a knife as dan would often say

You are right but it was the speed that is of interest as one has to move fast to follow the recoil. I think the stone lock or kettlebell might be a suitable example of using strength as in the following RSF post:

https://rumsoakedfist.org/viewtopic.php ... 700500c6fa
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Re: Punch retraction

Postby suckinlhbf on Sat Oct 24, 2020 3:41 pm

advancement of martial arts and sciences

I believe verbal explanation together with body contact (口传身授) is the way to pass on martial arts skills. DVD, youtube, books, & research papers ....do not really help to produce a martial artists other than a martial art practitioner for fun and health, and they are not even close to advancement of martial arts. The readers and reseachers can only see what they can see and do research on what they see. I am not object to books and researches. Most of the time, there are lot of misinterpretations on what the writer wants to say.
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