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Post by Bob Davis on Jul 9, 2012 10:32:52 GMT
I know that this is an old chestnut of karate forums (but things are quiet at present but can anybody explain the physics of why the "snap back" in a punch is supposed to deliver more power than just "pushing through" I can see reasons for snapping back but when it comes to delivering absolute maximum power I still have never understood why this would deliver more power to the technique, it seems counter intuitive to me.
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Post by Allan Shepherd on Jul 9, 2012 11:42:39 GMT
Hi Bob
I think it is something to do with kinetic energy?? Although a technique is "snapped back" the energy contained within the technique due to it's initial motion is further enhanced similar to a shock wave. The energy still radiates out through the object.
During training the other week we practiced a punching technique called tai shin te. From a very relaxed shizentai one side of the body is completely relaxed whilst the other side utilises a punch (say chudan although we can use gedan or jodan) with total relaxation immediately after contact (no sundome) that made the technique feel almost like whiping the target.
Best Regards Allan
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Post by Bob Davis on Jul 9, 2012 14:23:55 GMT
Kinetic energy (in my limited understanding) within the realms of delivering a punch is governed by mass and final velocity, i.e. the amount of power in a punch comes from a) the mass behind it (so you maximise the weight you put behind a punch with good technique) and b) how fast the punch is traveling when it connects (not the acceleration but the final velocity). These 2 give you the amount of energy available to transfer from the punch.
Given that your mass will be relatively constant, once you've learned to deliver it maximally, then speed is the big factor in power (and given that your limbs are of limited in length then better acceleration does give you a greater speed on impact).
I can understand all that BUT how does the "snap back" help any of this from a purely physical point of view?
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Post by jimlukelkc on Jul 9, 2012 15:50:44 GMT
I am with you Bob, I can understand how snapping back to a guard position or not over-extending to a point of unbalance would be advantageous ; but i cannot see how it imparts more power to pull a technique backwards. Perhaps this has been misunderstood in that the hikite hand snapping back can lend impetus to the out-going limb?
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Post by Allan Shepherd on Jul 9, 2012 17:04:14 GMT
There is no hikite with tai shin te.
The power in a "snap back" technique has penetrated the target and the quick withdrawl of the punching arm allows the shock wave to travel into the target and through it as opposed to being absorbed by the extented fist/arm/shoulder etc. Works for me!
The tai shin te technique can be performed in either kihon sonoba or kihon ido, either way there is mass and velocity in both. To what degree is dependant upon the karateka's ability to perform this technique. ` Best Regards Allan
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Post by Bob Davis on Jul 9, 2012 17:19:28 GMT
Yes, but in what way does the quick withdrawl create a "shockwave"? You transfered all the energy from the strike at impact, everything after that is just you moving away from the target.
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Post by Allan Shepherd on Jul 9, 2012 18:10:42 GMT
Hi Bob
To put it quite simply..I don't know!! All I know is that it works for me on a makiwara so my assumption would be that it would work on a body. Crash test dummy required, apply within??
Any scientist/astrophysicist/boffin etc on the boards?
Best Regards Allan
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Post by th0mas on Jul 9, 2012 19:15:08 GMT
Hi Allan I think your perception is an artifact of the Makiwara, rather than an, as yet, undiscovered new branch of science (sorry couldn't resist The Makiwara is essentially spring mounted so that when you hit it the makiwara gains potential energy from the kinetic energy you apply through your strike (in the physics sense not in the woo woo chi sense of energy) essentially spring loading it. At this point the makiwara is trying to spring back, producing the vibrating response. After a certain point there is a law of diminishing returns, where applying further force does not increase the effect but infact can make it worse... Basically the more force you apply, through follow through, increases the resistance of the makiwara which in turn dampens the effect of your punch, which in turn will feedback on the makiwara reducing the vibration as it is applied back into the punching arm, rather than being able to "spring free". A snap punch may maximise the effect given the impression of a shock wave, because your punch does not get in the way of the vibration of the makiwara.... Logically when striking force = mass x acceleration, if your body has reached maximum acceleration you will have reach the optimal level of force which is a good point to retract your punch to re-chamber for a second strike (all things being equal of course - you might actually want to continue to drive your punch with your bodies momentum for other combatitive benefits) This leads onto a slightly different but equally interesting discussion around training aids/approaches and how well they represent hitting a real body and essentially how training with these methods can lead to trained responses that are not necessarily beneficial to your goal of maximum effectiveness (i.e. Air punching, gaming whilst sparring, hitting heavy bags, using head guards and boxing gloves etc..)
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Post by Allan Shepherd on Jul 9, 2012 19:51:59 GMT
Hi Tom
"After a certain point there is a law of diminishing returns, where applying further force does not increase the effect but infact can make it worse..." Exactly my point, the impliment of force is withdrawn but the consequences ie the shock wave remains.
"A snap punch may maximise the effect given the impression of a shock wave, because your punch does not get in the way of the vibration of the makiwara...." Exactly my point also, the punch does not get in the way of the body vibration (shock wave) similar to the makiwara vibration (shock wave) since the fist has been withdrawn.
Like I said it works for me. Next time I train I will ask for crash test dummy volunteers!!
Best Regards Allan
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Post by th0mas on Jul 9, 2012 21:23:49 GMT
Hi Allan
I think you will have to get some gullible crash test dummies...
Couple of points: The human body does not react to being hit in the same way as a post-mounted makiwara. My previous post was suggesting that your perception of effectiveness is based on how the Makiwara vibrates which I don't believe equates to "damage" or additional force on your target.
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Post by Allan Shepherd on Jul 9, 2012 22:09:20 GMT
Hi Tom
I was actually joking about the crash test dummy volunteers!!
Best Regards Allan
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Post by makoto on Jul 10, 2012 8:34:47 GMT
Use a phone book, volunteer, and video the event. Then post it hear. I would like to see how snapping back a punch creates more shock to an opponet. I might be closed minded, but I just do not see how pulling away from an object creates more force. Must be the vacum created on the pull back or something like that.
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Post by genkaimade on Jul 10, 2012 10:54:50 GMT
Okay, so here's my A Level Physics answer.
F = m * a (where F is force, m is mass, and a is acceleration)
a = dv/dt (where d indicates a change, v is velocity, and t is time)
Therefore F = m* (dv/dt)
This effectively tells us that the acceleration can be thought of as the rate of change of speed. Applying this to our karate situation, the "snap" provides a mechanism to greatly reduce (as compared to letting the target slow down your fist) the time over which the acceleration occurs (in the +/- direction, it does not matter which), therefore greatly increasing the acceleration and therefore the force as per the formula.
I think.
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Post by Bob Davis on Jul 10, 2012 12:04:00 GMT
Ok Alex, here's my thoughts. (and my understanding of physics is probably at a similar level to yours I'd guess The acceleration takes place before the punch connects, you may well still be accelerating at the point of impact but the kinetic energy available for transfer is a function of the velocity (squared, so speed make a big difference). What you are dealing with force wise is the time it take for the punch to decelerate to zero, i.e. if the punch stops quickly it will be more powerful that if it comes to a halt slowly (and thus becomes a push) HOWEVER this is beyond your control and depends upon the mass, density and reaction of the target (which is why it is possible to "ride" a punch and remove a lot of the force from it). Attempts to increase the force by artificially reducing the time in contact (by snapping back) will not have the same effect as what you are in fact doing is removing the force before all the energy is transferred into the target. It's like driving a car into a crash barrier, I don't think anybody would for a second believe that if you threw it into reverse at the last second to reduce the time in contact it would generate a "shockwave" that would provide more power to the collision than keeping you foot hard on the accelerator. Like I've said, I can see many reasons for the snap back but absolute power generation isn't one of them.
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Post by genkaimade on Jul 10, 2012 15:08:40 GMT
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Post by Allan Shepherd on Jul 10, 2012 18:06:29 GMT
Well Gentlemen
Some great explanations of "A" level physics, but what does it all mean? Can we agree to disagree? Can we actually apply theory to actual physical events that have us so confused. Remember when it was considered that the planet Earth was square?
Been trawling through some old postings on TSW and an entry by Magpie "Gyaku Tsuki to snap or to thrust" dated 08/01/2008 related to an article in SKM issue number 72 entitled "The biomechanical rationale of the snap-punch" by Bill Laich.
Contained postings by Kensei, plwilloughby and Makato to name a few. Interesting reading!
Best Regards Allan
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Post by Bob Davis on Jul 10, 2012 20:11:58 GMT
Of course we can agree to disagree (if disagree we do , it wouldn't be much of a discussion forum if we all thought exactly the same. My thought is that by understanding the theory (I know not always a popular word around here ) then I can work my technique correctly to achieve what I want to achieve and then apply it appropriately. Isn't that exactly the point, if it wasn't for stepping back from the "accepted" wisdom and looking to understand the "why" we'd still be living on a flat Earth around which the Sun was carried on the back of a chariot.
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Post by Dod Watt on Jul 10, 2012 23:23:57 GMT
I think that there is an element missing from this formula, and it is vital to the passing on of energy and where you can may be relate to the effectiveness of the snap back, it is known as inertia of rest, i.e. think of having to stand on a bus when it is full, the bus driver has to put on the brakes quite heavily, what happens, well us that is standing still keep travelling and people that is sitting has their energy absorbed by the seat they are sitting on.
So therefore if we were to thrust our punch in, we are unconsciously holding on to potential force to be applied, but when we use the snap back, we are letting go of the energy at the point of impact and concentrating on the return of the striking hand, and that's where the rule of inertia of rest comes in, I hope that make sense
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Post by tomobrien on Jul 11, 2012 1:42:07 GMT
All I know is that when you hit a heavy bag you are never supposed to push the bag. When you watch & listen to a good boxer you can tell by the sound of the punch & the way the bag moves. The sound is loud but the bag is not being pushed around. As quickly as the hand goes out it should come back to the side of the jaw, where it came from, just as fast.
Thanks, Tom
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Post by barryives on Jul 11, 2012 8:19:21 GMT
But isn't the boxer's hand returning fast to 'cover' rather than to increase the power of the punch?
And I can't help thinking that with a snapped back punch, the fist will be decelerating more as impact approaches (since you are thinking about withdrawing it), thus decreasing the force at point of impact
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Post by Bob Davis on Jul 11, 2012 9:16:02 GMT
Only if the seats are facing backwards Dod Even so, the point of punching IS that the energy is absorbed by the target (in this case the seat), the only reason it feels like a gentle push is because you are already in contact. We are not looking to move the target (as in a push) but to transfer the energy into it as fast as possible (in fact, the less the target moves the more damage we are likely to do). I'm not advocating a "thrust" or "push" just questioning what the snap back adds by way of power and this idea of the "shockwave" (If anyone can explain why I'm perfectly happy to accept it, I just haven't seen it yet). I originally thought that (and it may be true if you are targeting surface rather than penetration) but I suspect what happens in reality is that with a punch that is not going to be snapped back you tend to add more counter-tension (like the exaggerated "kime" seen in air punching) where as with the snap back you actually relax more into the punch as there is no need for counter tension as you are going to snap back. The result of this is a faster punch and (getting back to the mock physics ) the kinetic energy available for transfer is "mass x velocity squared" so any increase you can make in speed is squared so makes an enormous difference, however, it is not the snap back per se that gives you this but rather the relaxation and lack of counter-tension going into the punch.
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Post by th0mas on Jul 11, 2012 9:28:21 GMT
edit; Damn Bob.. you beat me to the draw All I know is that when you hit a heavy bag you are never supposed to push the bag. When you watch & listen to a good boxer you can tell by the sound of the punch & the way the bag moves. The sound is loud but the bag is not being pushed around. As quickly as the hand goes out it should come back to the side of the jaw, where it came from, just as fast. Thanks, Tom Ok there are a number of things going on here and a number of the posts have touched on different elements… And I apologise this may get a bit wordy. I think we can all agree (well I hope so...) that to maximise the impact, you don't want to have any antagonistic muscles or other body physiology acting against the punch you are delivering into the target. This is essentially the point about "relaxing when striking" vs over-tension ... a common problem with karateka who have not done enough "hitting things" to supplement their air-punching form. And there are a lot of pedantic discussions on MA forums across the WWW about how best to do this, which I don't think add to this discussion. Ok, the pushing problem has more to do with a desired outcome. You don't want to push your target away, as that transfers the striking energy into moving the whole targets body and not into moving the targets tissues and organs (to create trauma, broken bones or knockouts etc) This is all about speed of the punch and how well the bodies tissues resist vs the strength of friction on the soles of the targets shoes (ok I am making some assumptions about angle of trajectory, lets assume the punch is perfectly horizontal and oversimplifying the human body somewhat) As Bob points out rolling with the punch is a way of reducing the tissue/trauma damage by transferring the energy of the punch into moving your body... Dod's bus example needs to be flipped on its head (sorry Dod). The passengers had potential energy because they are on a moving bus relative to the ground (or a wall). If the bus hits a wall then all the kinetic energy of the bus is transferred into the wall. As soon as the bus hits the wall the passenger’s potential energy changes into kinetic energy. The force of the passengers slamming into the rapidly crumpling front end of the bus will also transfer their kinetic energy into the wall (yuk…). If the bus brakes, the kinetic energy is transferred to the brake pads and disks, the surface of the road and any moving objects in the bus (i.e. the passengers and the luggage). If you begin to "snap-back" prior to hitting the target (no matter how fractionally small that time gap is) you are actually reducing the energy transfer.. a little like applying the brakes before you slam into the wall. This is basically a classic Newtonian laws of conservation of momentum: The snap is not adding any additional force or energy to the punch - period..that would break the 3rd law. If you do not want to apply the energy of the follow through into the punch - given that it won't be adding further trauma damage but rather unbalancing and dominating benefits - then snapping back is the right thing to do, certainly if you want to punch again. In Shotokan Kihon we predominantly train to deliver punches at long range. The chances are the average Karateka is most comfortable at long range and will want to maintain the distance and snapping back punches fits into that strategy.
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Post by makoto on Jul 11, 2012 10:14:13 GMT
Boxers generally do not snap back their punches.
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Post by genkaimade on Jul 11, 2012 15:14:53 GMT
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Post by makoto on Jul 11, 2012 16:28:29 GMT
Everybody compares karate, and punching, to sports like baseball, boxing, etc. Yet, we have this thing called kime. And kime can be a mental aspect and a physical aspect. Yet, the idea of kime(it is not called that) is knowing in the weight training world. Actually, the way karate is done we should be looking at the relationship between proper form in weight training and karate application. You need to deliver the force, send it on its way, send it flying, throw it, etc. What the hand does after wards does not matter.
The problem is, some people can, with a whip like total body action do a snap back punch that has the whole amount of possible energy behind the punch. However, with many others they just use arm action. They think they are doing their max, but it is nothing more than just arm action. I think this comes from copying and not understanding.
I do not snap back, but I can do a whip like snap back punch very well. Why can I do both? Because, knowing how to use the body to create and deliver energy into the target is 80% of the technique. Not meaning to brag. I think I understand what is going on the this thread, in spite of having no knowledge of physics, or a care for it.
I think if there was a way that snapping back the projectile created more energy then cork guns would be the most popular weapon. Instead, we have Guns. Lets keep it real people. Snapping back without passing on the maximum amount of energy/effort/force/ki/whatever into the target is not karate.
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Post by th0mas on Jul 11, 2012 18:40:09 GMT
I think we may have a semantic problem here. I use the term kinetic in the purely scientific sense of the word as a description of the transfer of energy (something that can be measured in jules) and it is absolutely the same if you perform a push kick or a snap kick. i.e. the sum total of the energy in a snap kick can be described as a combination of kinetic and potential energy. There is nothing especially special going on with the snap kick that does not follow the normal rules of physics. The difference between the snap kick and the push kick, in terms of force and effect, is defined by the speed and acceleration of the kick at the point of contact. And clearly there is no further follow-through for the snap kick.
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Post by th0mas on Jul 11, 2012 18:49:49 GMT
Everybody compares karate, and punching, to sports like baseball, boxing, etc. Yet, we have this thing called kime. And kime can be a mental aspect and a physical aspect. Yet, the idea of kime(it is not called that) is knowing in the weight training world. Actually, the way karate is done we should be looking at the relationship between proper form in weight training and karate application. You need to deliver the force, send it on its way, send it flying, throw it, etc. What the hand does after wards does not matter. The problem is, some people can, with a whip like total body action do a snap back punch that has the whole amount of possible energy behind the punch. However, with many others they just use arm action. They think they are doing their max, but it is nothing more than just arm action. I think this comes from copying and not understanding. I do not snap back, but I can do a whip like snap back punch very well. Why can I do both? Because, knowing how to use the body to create and deliver energy into the target is 80% of the technique. Not meaning to brag. I think I understand what is going on the this thread, in spite of having no knowledge of physics, or a care for it. I think if there was a way that snapping back the projectile created more energy then cork guns would be the most popular weapon. Instead, we have Guns. Lets keep it real people. Snapping back without passing on the maximum amount of energy/effort/force/ki/whatever into the target is not karate. My understanding of the Japanese translation of Kime is more an expression of intent, The importance of focusing on the end goal...,than the more prescriptive common western interpretation which describes the physical activity of tensing for a split second at the point of impact. (I know you are based over there, so maybe you can confirm that)
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Post by Rob S on Jul 11, 2012 19:18:09 GMT
Kimeru means to decide. So the kime becomes the moment of total decision/intent. i.e. 'touching time' the decisive moment of impact where shin gi tai all come together as a fusion in a very short intense moment in time. IMO
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Post by th0mas on Jul 12, 2012 7:19:41 GMT
Thanks Rob..
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Post by genkaimade on Jul 12, 2012 9:10:47 GMT
I use the term kinetic in the purely scientific sense of the word as a description of the transfer of energy I don't mean to be pedantic (and just for the record, in all of these comments I don't claim to be completely correct or "know it all" per se), but 'transfer of energy' is not what kinetic energy is. Kinetic Energy is simply the energy which something has because it is moving. Transfer is something totally different and dependent on all sorts of things (which I think the articles previously linked to explain fairly well as far as "snapping" goes).
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