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Peng Jin?
Comments
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Your brain doesn’t decide (voluntary or involuntary) to use one type of a contraction to lift and object (concentric) and another to lower it (eccentric).
He had no control over the sudden switch to concentric either. If was purely because the opposing force disappeared.
The reason why I posted this,
"For voluntary muscles, all contraction (excluding reflexes) occurs as a result of conscious effort originating in the brain. The brain sends signals, in the form of action potentials, through the nervous system to the motor neuron that innervates several muscle fibers."
https://en.wikipedia.org/wiki/Muscle...ion#Physiology
is because it counters your argument that the movement after the arm was freed was a concentric contraction. You are saying that in this case, concentric contraction occurred without a decision from the brain and the person had no control over it. The link above states the opposite, that all muscle contraction occurs as a result of concious effort originating in the brain.
In relation to me stating that the muscle was contracting eccentrically just before the arm was released,Nobody said it wasn't???? That has never been an issue,
Actually in post 80 you stated that the muscle was under isometric yielding contraction before the hand was released.
You are saying one thing in one post then changing to something else when challanged.He is pulling harder and harder and the other guy is opposing it. So it’s isometric yielding. But when the other guy lets go suddenly, removing the opposing force. It instantly becomes a concentric movement.
So you think that after a muscle is under eccentric contraction/lengthening under resistance, that as soon as the opposing force is removed, the muscle without concious effort will contract concentrically? This is not how a muscle works after being released from eccentric contraction. Again,The question was what muscle makes the hand rise AFTER its let go.
"During the eccentric phase of movement, the muscle absorbs energy. This work is done "by stretching the muscle and in this process the muscle absorbs mechanical energy".This mechanical energy is dissipated or converted into one or a combination of two energies.
Heat
The energy that is absorbed by the muscle will be dissipated as heat if the muscle is being used as a "damper or shock absorber". This leads to increase in body temperature.
Elastic Recoil
The energy that is absorbed by the muscle can be converted into elastic recoil energy, and can be recovered and reused by the body. This creates more efficiency because the body is able to use the energy for the next movement, decreasing the initial impact or shock of the movement.https://en.wikipedia.org/wiki/Eccentric_training#Energy
This is what brought the hand towards the persons own face when the opposed force was released. Elastic recoil from eccentric contraction.
I thought about this as I can easily use isometric yielding contraction and maintain the spring for a long time. So I dug a little deeper into the reference behind it.the time you have to use it (mechanical energy) is in the order of milliseconds. You can't yield isometrically and hold on to this energy.
http://www2.nau.edu/~sll/pubs_files/NIPS2001.pdf
It states, "The time course of stretch and recovery of elastic recoil energy are dependent on both the magnitude of the forces involved as well as the compliance (spring property) of the muscle." The article also mentions that the spring property of the muscle can be increased through training and this is what we in Wing Tsun with 1000s of hours of chi-sau practise.
I don't know where you got this figure of milliseconds.
There also is a relationship between mechanical (Kinetic & Potential) energy and eccentric training and there is a relationship between eccentric training and isometric yielding.
https://en.wikipedia.org/wiki/Isometric_exercise#Overcoming_versus_yielding
"yielding wavers slightly into concentric and eccentric actions due to inexact control,"
Therefore it logically follows that there is a relationship between isometric yielding contraction and potential energy.
So you Doug and Cletus are out now. I understand the reasons why. You are great for making vague, subjective, emotive, personal, smart ar#e comments but are short on specifics when we really get into the details.0 -
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You're intentionally avoiding simple questions. You ignore examples that prove you wrong too.
I mean at one point your denied the resistance of gravity.
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Hi Mellor,
I am not intentionally avoiding simple questions and throughout this thread I have invited anyone to query, comment or criticise anything. I have said that I would "welcome comments, specific feedback, keep questions/comments coming, if you disagree we can drill down further/fire away, etc."
The problem is that you, Cletus and Doug keeping making vague, subjective opinions in the hope that some of them gain traction and stick. I can't and won't reply to everything you say as for me, there is a hierarchy of issues that need to be dealt with before we move onto something else. As an example, we cannot discuss spring force in Wing Tsun using muscular contraction as a reference if you do not understand what simple concentric contraction is.
If we did start to talk about the spring force, it would just bring us back to what is concentric contraction. But I will answer your questions nonetheless.- Do you think the guy in the video is really sending him flying with a push like that?
- Do you believe that technique will be the strongest push?
- I mentioned the fact he moves from the hips proves he is acting. You never touched on that.
- If you believe it is real. Can you please replicate with lying supine with a weight. As described in post #78
2. Depends on the context but it can be a good way of using your body.
3. You are right. Its not a great video. There is the "woo woo" factor as you call it and there is a lot of martial fluff including the black guy jumping back. That's why I said "it did a reasonable job of explaining it (arms working eccentrically, torso working eccentrically) on a basic level. The main part I liked was that of bringing spring force to an opponent rather than them coming to you.
4. You can't replicate it lying supine. In the example in the video (if it was explained properly), the person moved towards the resistance and by applying deceleration as their elbow joint flexed (Thanks Cletus
), allowed potential energy to build up in their triceps during the eccentric phase. They can't move towards the resistance lying supine.
I will get back to you on your points regarding basic muscular contraction.0 -
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So you agree he's not really pushing him and the black guy is jumping back. Which was my criticsm from the start.Michael O Leary wrote: »1. No
3. You are right. Its not a great video. There is the "woo woo" factor as you call it and there is a lot of martial fluff including the black guy jumping back.
...but your still suggesting it's a legit technique???
The weight will move toward you due to gravity. You can use all the eccentric contraction you like to decelerate it. And the "potential energy can build up.4. You can't replicate it lying supine. In the example in the video (if it was explained properly), the person moved towards the resistance and by applying deceleration as their elbow joint flexed (Thanks Cletus), allowed potential energy to build up in their triceps during the eccentric phase. They can't move towards the resistance lying supine.
It makes no sense to say you need to move to towards the resistance. As the position of two bodies is completely relative. Whether you move to the object, or the object moves towards you makes no differences as far as your triceps are concerned.
It can't be replicated, because it doesn't exist.
For all the wiki science links you posted, and studies too. You haven't produced a single one to that describes this phenomenon. Because it doesn't exist.
Also, in the arm-wrestle-face-punch clip, you it was the spring effect that caused the arm to fly up (and not a concentric contraction). But he didn't need to move towards the resistence.0 -
I think that what the people in the video are trying to explain/demonstrate, is independent of their ability to do so.So you agree he's not really pushing him and the black guy is jumping back. Which was my criticsm from the start.
...but your still suggesting it's a legit technique???
I also would not see this as just a technique. I would see it as more of a way to demonstrate how your can use your body. It is exaggurated to contrast two different ways of producing force but would be more subtle when used in techniques, etc.
Yes. If I understand you correctly, I agree with you.The weight will move toward you due to gravity. You can use all the eccentric contraction you like to decelerate it. And the "potential energy can build up.
As the position of two bodies is completely relative. Whether you move to the object, or the object moves towards you makes no differences as far as your triceps are concerned.It makes no sense to say you need to move to towards the resistance.
in the arm-wrestle-face-punch clip, you it was the spring effect that caused the arm to fly up (and not a concentric contraction). But he didn't need to move towards the resistence.
I am trying to understand your point so that I can directly address it. In order to voluntarily store potential energy in a muscle, connective tissue, fascia, etc, the muscle needs to decelerate under resistance. This is called eccentric contraction or the eccentric phase of a movement.
As a simple example, if someone pushes your arms and you allow your elbow and shoulder joints to flex under deceleration, the triceps and anterior deltoids will be the primary muscles to be placed under eccentric contraction, facilitating storage of potential energy. If there is no resistance, meaning they don't push then there is no eccentric contraction, potential energy, etc.
As a variation on this simple example, if the other person does not push on your arms for you to store potential energy, using your own arms, you can make contact with their arms, torso, etc and move towards your own arms while allowing your elbow and shoulder joints to flex under deceleration. It will give the same effect.
So whether the resistance comes to us or we go towards the resistance, in both cases as above, elastic recoil/potential energy is stored. While stored, if the resistance is removed the potential energy is transformed/converted into kinetic energy and the triceps/anterior deltoids contract, automatically extending the arm.
To bring it back to the examples of two people and bench press, if the initial opponent who is pushing on our arms using concentric contraction in his own anterior deltoids and triceps, suddenly drops his arms, our anterior deltoids and triceps (previously)under eccentric tension will automatically extend our arm.
When having completed the concentric phase of a bench press, we allow the weight of the bar to flex our elbow and shoulder joints with our anterior deltoids and triceps (and pecs) under eccentric contraction, if the bar suddenly disappears, then again our arms will automatically extend as per the examples above.
But I think that your question/comment is if the resistance does not disappear, how can an opponent be bounced back during the build up of elastic recoil/potential energy while this will not happen with a barbell during the eccentric phase of a benchpress? If this is not what you mean, please let me know.
My answer would be that stability plays an important role in producing force. Here is a comment on stability that I wrote upon in a previous thread.Michael O Leary wrote: »A very important part of striking or movement in general is stability. This is where the non moving muscles are working to minimise recoil of the body upon impact.
This is of huge importance in Wing Tsun and is reflected in all our exercises and drills. When striking pads I tell students to pay at least as much attention to controlling force (stability) as to producing force. Students can lack power due to trying to produce excessive force without appropriate stability.
One of my students was invited to try a free Krav Maga class so he went along. The front kicks looked like all front kicks but they had no power due to lack of stability and everyone including the instructor bounced back due to recoil on impact.
In the case of the bench press, the resistance (the bar or if you like, gravity) is constant so there is no recoil/bounce. However, depending on the environment, if gravity was switched on and off like a flickering lightbulb, we would see similar recoil/bounce.
In the case of one person applying force concentrically to another working eccentrically, depending on the first persons stability in relation to the amount of force they are trying to produce together with the amount of potential energy stored by the second person, there will be varying degrees of recoil/bounce. Maybe I should have used the word “recoil” instead of “bounce” but this is what can happen when you use plain, everyday English.
For everyone, have a read of what I have written and think about it for a little bit instead of the usual knee jerk reactions. If you have any comments or queries, just ask. And if anyone wants to question me further, come to a free class and ask me to go through it in person. You don't have to say who you are. Just say that you saw the thread and wanted to get more detail in person or feel the different ways of producing force. We can do it in class and I can stay behind and answer your specific queries in person. No problem.
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All the statements were very clear tbh, and I explained them as I went along.Michael O Leary wrote: »Here is the thing. I don't mind being wrong if I get to learn something from it. But you, Doug and Cletus just made very vague, subjective or plain incorrect comments without backing them up with any type of reference.
Have I ever said that that wasn't the case?Tension in the triceps can also do other things. (Isometric Overcoming, Isometric Yielding, Eccentric)
we are talkign about extending the arm.
The arm can also be extended by other forces other than tension in the triceps working concentrically.
Hold your arm in the air in some type of basic guard with the elbows flexed. Gravitational force is pulling your arm towards the ground but as you hold your arms in the air, potential energy is stored.
https://en.wikipedia.org/wiki/Potential_energy#Gravitational_potential_energy
When you relax the muscles holding your arms, the elbows will extend and the triceps will shorten as your arm falls. However the triceps are not shortening under concentric contraction. This definition of concentric contraction states, "In a concentric contraction, the muscle tension rises to meet the resistance, then remains the same as the muscle shortens."
https://en.wikipedia.org/wiki/Isotonic_contraction
In the example above, the muscle tension does not rise to meet the resistance as there is no meaningful resistance. Gravitational force does not resist the movement but actually facilitates the movement. The only opposing force is air resistance but this is negligible compared to the kinetic energy which was released by the stored potential energy.
This is an example of the arm extending without the triceps contracting concentrically. The movement was initiated by the release of stored potential energy which automatically converts into kinetic energy. It doesn’t matter what position this is done in. In my example of someone putting pressure on our arms, the same rules will apply. As long as the potential energy (which is stored in muscles, connective tissue, fascia) is greater than air resistance and gravitational force, when the arms are released the potential energy will be converted into kinetic energy and the arms will extend without the need for the triceps to contract concentrically.[/QUOTE]0 -
All the statements were very clear tbh, and I explained them as I went along. If you think sometihng is incorrect, you can point it out, but so far you've been wrong imo.Michael O Leary wrote: »Here is the thing. I don't mind being wrong if I get to learn something from it. But you, Doug and Cletus just made very vague, subjective or plain incorrect comments without backing them up with any type of reference.
Have I ever said that that wasn't the case?Tension in the triceps can also do other things. (Isometric Overcoming, Isometric Yielding, Eccentric)
We are talking about extending the arm. None of that applies.
Of course, such as an external force. That too has never been disputed by me.The arm can also be extended by other forces other than tension in the triceps working concentrically.
I know what potential energy is. I've studied physics.Hold your arm in the air in some type of basic guard with the elbows flexed. Gravitational force is pulling your arm towards the ground but as you hold your arms in the air, potential energy is stored.
It is not "stored", but rather It simply exists.
Energy cannot be created, it can only be changed from one form to another.
I agree. The external force of gravity is extending the arm. Nobody has claimed different. That's disputes nothing I've said.When you relax the muscles holding your arms, the elbows will extend and the triceps will shorten as your arm falls. However the triceps are not shortening under concentric contraction.
If you think that it does, then you don't understand what I've been saying.
Another example would be me walking up and extending you arm. Which also changes nothing in this example.This is an example of the arm extending without the triceps contracting concentrically.
We were talking about the arm being extended by the tricep. Not an external force. There is no way for the tricep to fully extend the arm without contraction concentrically. You still haven't said anything to suggest that it was true.
Going back to the facepunch clip.- Which muscle flexed the arm up to the face?
- Did this muscle shorten?
- Was there resistance (including gravity)?
If you go back to the very first post I made, and ever post I've made I never denied that elastic recoil of muscles can return energy to a movement. I've given numerous examples of this happening. (weight lifting, running, hopping, etc).As long as the potential energy (which is stored in muscles, connective tissue, fascia) is greater than air resistance and gravitational force, when the arms are released the potential energy will be converted into kinetic energy and the arms will extend without the need for the triceps to contract concentrically.
I also said at the start the all of the things you are talking about do exist, (the wiki page for each proves that).
The issue is you applying them is a selective way, often ignoring other factors. And you are also really overstating the magnitude of these forces.- In order to utilise the elastic recoil. The eccentric needs to be followed by a concentric. Eccentric and concentric are describing the movements, not the contrations on a cellular level.
- The recoil will either A) reduce the energy required to repeat a movement, or ,
Increase the max force produced. - Examples of each of these; A) reduced energy remands when hopping at your natural rhythm, verses a series of single hops, and , stop-n-go bench presses, vrs pausing on the chest bench (ditto for press-ups)
- The recoil returns only some of the energy absorbed. The amount varies depending on muscles in question, and energy demands overall. It could be 5% (heavy lifting, high force), or 50% (light hopping, low force).
- Time is a crucial factor. In the hopping example, a natural rhythm (c. 0.5sec) recovers the most energy (this is actually why that rhythm feels the best). Slowing this pace by half (1sec) doubles the energy required to hop because all the recoil dissipates. It's really a case of use it or lose it.
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I've studied physics.
Good for you.
It is not "stored", but rather It simply exists.
This is a quote from Wikipedia on what Potential Energy is. It refers to Potential Energy being stored.
Potential energy is the stored or pent-up energy of an object. Potential energy is often associated with restoring forces such as a spring or the force of gravity. The action of stretching the spring or lifting the mass is performed by an external force that works against the force field of the potential. This work is stored in the force field, which is said to be stored as potential energy. If the external force is removed the force field acts on the body to perform the work as it moves the body back to the initial position, reducing the stretch of the spring or causing a body to fall.
https://en.wikipedia.org/wiki/Potential_energy
The Wikipedia article goes on to state that among the various types of Potential Energy are Gravitational Potential Energy and Elastic Potential Energy. For the purposes of looking at Elastic Recoil in your arm wrestling example and my example of how we use spring force in Wing Tsun, Elastic Potential Energy is the type that best describes what is going on.Going back to the facepunch clip.
- Which muscle flexed the arm up to the face?
- Did this muscle shorten?
- Was there resistance (including gravity)?
In the arm wrestling clip above, just before resistance was released, there was a lengthening of the biceps while they were under resistance from the opponent. This is known as eccentric contraction.Eccentric and concentric are describing the movements, not the contrations on a cellular level.
Here is an extract from the Wikipedia article on Muscular Contraction which states that the muscle has a different physiological response depending on whether it is under concentric or eccentric contractions.
"When eccentric contractions are used in weight training, they are normally called negatives. During a concentric contraction, muscle fibers slide across each other, pulling the Z-lines together. During an eccentric contraction, the filaments slide past each other the opposite way, though the actual movement of the myosin heads during an eccentric contraction is not known."
https://en.wikipedia.org/wiki/Muscle_contraction#Eccentric_contraction
Elastic Potential Energy is not only stored in the muscles but also the connective tissue (ligaments, tendons & fascia). This tissue is elastic, will stretch under resistance, will shorten once resistance is removed and can flex or extend a joint to varying degrees while what would normally be the agonist is passive.
In the case of the arm wrestling above, there was no meaningful resistance once the arm was released. The amount of potential energy stored in the biceps and connective tissue which was converted to kinetic energy upon release, rendered any resistance such as inertia, gravity or drag negligible. With no meaningful resistance, the tension in the muscle fibres lowered as the muscle moved towards relaxation.
So back to your list of questions.
1. No muscle flexed the arm up to the face.
2. Yes, the biceps shortened. (Passively)
3. Yes, there was resistance but it was insignificant when compared to the kinetic energy and does not qualify as resistance when we talk about concentric contraction.
You state that gravity is an external force which will move a joint while the muscles remain passive and that if you extended my arm, that would another example of an external force. In the case of the arm wrestle above, would not the opponent also be an external force?
If a person lifts a book into the air, Gravitational Potential Energy is being stored in that they are working against gravity. When they let go, the book will fall to the floor as they allow gravitational force to do its work.
If a person pulls the wrist of someone else towards them in an arm wrestle, Elastic Potential Energy is being stored in that they are working against an opposing force. When they let go, the opponents arm will fly to their own face as the first person allows Elastic Potential Energy to do its work.
However I agree with most of what I think you are saying. Concentric contraction does not need to be added for a once off, sub optimal movement to occur. However, to maximise the efficiency of a once off movement and to maintain a cycle of movements, such as hopping or running, concentric contraction must be added to the released spring.The issue is you applying them is a selective way, often ignoring other factors. And you are also really overstating the magnitude of these forces.
Fine. We can discuss these in specific detail.0 -
https://www.youtube.com/watch?v=jdXvwAtVfAE
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