Punches: Recoil vs. Follow Through

[RichardZ]

tonydee, I have seen these studies and seminars from such over decades. I too, am very much skeptical. It would seem, as there are martial artists out there, who finally grasp the "realities" of martial arts, and there are those, who in some way, have to set spmethiong beyond or different. Those same, usually have not studied anything new, other than a re-arrangement of something.

[sensei8]

I'm struggling with the "sledgehammer on a chain" pull-back idea. I just can't see how an extra requirement to be able to reverse direction suddenly at the end of a technique can increase the strength/explosiveness of the forwards movement. Again, I think it's psychological: the anticipation of needing to pull back encourages a snappier punch, a tendency to speed up the striking contractions. Still, I think snap or push can exist in the forwards movement anyway, it's more about the explosiveness of that motion, independent of the recoil. Thinking about breaking boards, I don't pull back afterwards: I hit straight through them and leave my arm out, and even when I'd just got 1st dan (1991) I could break three 300x300x18mm pine boards hanging loosely from someone's fingertips with a reverse punch (unsupported boards take a lot more 'snap' to break), and - in hindsight - I didn't even have good hip mechanics back then....

Have you ever been on the receiving end of a snapping wet towel? Well, that's a crude explanation of the bold type above.

If that wet towel doesn't snap back to serve its effectiveness, well, the only thing the wet towel will do for me is...well...get the other person wet.

[DWx]

I agree with tonydee, from a mechanics point of view, once the fist has impacted and the energy transferred, the recoil doesn't do anything. Of course its probably beneficial to recoil in preparation to punch again and, like Tony said, gets the snappier punch.

[tallgeese]

Recovery is for a return to defensive posture and positioning for more strikes. I don't think the method of recovery has anything to do with energy transfer to the target.

[Jay]

Right here we go, elementary physics

A punch with snap is much better than a punch without snap. A punch without snap is just like a push which although can hurt will do less damage.

Pressure onto the body is what creates damage. Pressure is the force of the blow divided by the area in which it makes contact.

Thus if you are throwing a punch the area over which it hits will generally be the same. So lets look at why the snap works. Force of a object is determined by the rate of change of momentum, That is the momentum difference over a certain time period.

Momentum is the mass of an object multiplied by the velocity. The momentum for a punch is constant. because the mass and velocity of your arm are pretty much the same out as in. This is highly assumptive but makes things simple.

Remember that change in momentum=momentum/time=force

With the snap punch you spend less time in contact with the target thus increasing FORCE. FORCE over an area= Pressure=Damage

With the follow through punch you are spending longer in contact with the target which REDUCES FORCE. Which In turn reduced pressure=LESS damage.

If you are not snapping you are reducing the effectiveness of your punch.

[DWx]

Remember that change in momentum=momentum/time=force

With the snap punch you spend less time in contact with the target thus increasing FORCE. FORCE over an area= Pressure=Damage

Ok I only did up to A-Level mechanics and bits of particle physics in uni, but that doesn't make much sense to me.

Change in momentum basically means velocity or acceleration, so force=mass x acceleration , i.e. Newton's first law. Means you hit the target when you fist is travelling the fastest in order to gain maximum force. That's pretty straightforward. But it means its not so much spending less time in contact with the target as transferring the mass as fast as possible i.e. acceleration. Doesn't matter how long you are in contact for because if you are travelling fast enough when you impact the mass is transferred in a split second rather than over a longer time period which would happen if you were travelling slower. After the energy has been transferred as impact you can keep your fist there if you want, its not going to suck the energy back. Think car hitting a wall, once it hits and kinetic energy becomes impact, doesn't matter if you then accelerate in reverse, the damage is already done. Another example, a sledgehammer wont do more damage if you hit and then recoil. Once it's hit, it's hit.

You also have to punch through because your arm isn't travelling the fastest at the end of the punch, its travelling fastest at probably around 75-80% of the distance. No matter how fast you accelerate throughout the punch, you have to stop your arm at some point so you decelerate towards the end of the motion. Therefore to maximise the energy transfer you want to hit when its travelling the fastest, ~25% before full extension.

So for a better punch, don't decrease the time you are in contact, decrease the time it takes you to make contact. Also decrease the time/increase the distance before you have to decelerate and you will maximise the amount of acceleration created.

[joesteph]

So for a better punch, don't decrease the time you are in contact, decrease the time it takes you to make contact. Also decrease the time/increase the distance before you have to decelerate and you will maximise the amount of acceleration created.

DWx, do you think that if someone intends a punch with snap that, consciously or unconsciously, that person is actually delivering the punch at a greater speed than one intended with push?

An example would be that I'm delivering a snap punch to my opponent's face, as opposed to a push punch to his midsection. Do you think that I am, consciously or unconsciously, punching faster and pulling back more swiftly with the snap punch than with the push punch, the latter which I expect to end its forward motion within the opponent before pulling back?

[Jay]

Remember that change in momentum=momentum/time=force

With the snap punch you spend less time in contact with the target thus increasing FORCE. FORCE over an area= Pressure=Damage

Ok I only did up to A-Level mechanics and bits of particle physics in uni, but that doesn't make much sense to me.

Change in momentum basically means velocity or acceleration, so force=mass x acceleration , i.e. Newton's first law. Means you hit the target when you fist is travelling the fastest in order to gain maximum force. That's pretty straightforward. But it means its not so much spending less time in contact with the target as transferring the mass as fast as possible i.e. acceleration. Doesn't matter how long you are in contact for because if you are travelling fast enough when you impact the mass is transferred in a split second rather than over a longer time period which would happen if you were travelling slower. After the energy has been transferred as impact you can keep your fist there if you want, its not going to suck the energy back. Think car hitting a wall, once it hits and kinetic energy becomes impact, doesn't matter if you then accelerate in reverse, the damage is already done. Another example, a sledgehammer wont do more damage if you hit and then recoil. Once it's hit, it's hit.

You also have to punch through because your arm isn't travelling the fastest at the end of the punch, its travelling fastest at probably around 75-80% of the distance. No matter how fast you accelerate throughout the punch, you have to stop your arm at some point so you decelerate towards the end of the motion. Therefore to maximise the energy transfer you want to hit when its travelling the fastest, ~25% before full extension.

So for a better punch, don't decrease the time you are in contact, decrease the time it takes you to make contact. Also decrease the time/increase the distance before you have to decelerate and you will maximise the amount of acceleration created.

DWx effectively you a correct in what you are saying which is similar to what I was saying. I have had a long conversation with my housemate, we are both engineering undergrads.

I was slightly off with newtons second law. Effectively you always need a follow through on your punch or kick how much depends on the ability of the object to conserve the momentum. You do need to make contact at the point of maximum acceleration which as you correctly stated is roughly 25% before the end.

Basically you want to keep applying force until the object you have hit has absorbed all the momentum. Thus for a light object your fist velocity and his head will reach a maximum equilibrium velocity, that is when you retract because you cannot exert anymore force. Thus we decided was about 2-4inches. For something to the body because it has more mass you need to follow through more because it is a larger mass you need to be in contact longer so that the velocities equalize and then you pull back when you can no longer give momentum to it. This is probably about 6inches for a punch or a Bruce Lee said about 12inches for the sidekick as you can continue applying energy for a longer period of time thus the body is absorbing more. Which is where your kinetic energy comes into it.

Basically earlier I was talking about impulse.

This is a fairly complicated thing to be honest and im not 100% up to scratch on my physics, I design cars so its a bit different. But what my housemate was saying made sense to me.

Either way the problem is more complicated than just snap or follow through. You need both but to varying degrees and us as human seem to have an uncanny ability of feeling the correct amount.

So in other words you are correct with you analogies and I was off with my momentum which im not impressed with because I was at one point in time very good

[DWx]

DWx, do you think that if someone intends a punch with snap that, consciously or unconsciously, that person is actually delivering the punch at a greater speed than one intended with push?

An example would be that I'm delivering a snap punch to my opponent's face, as opposed to a push punch to his midsection. Do you think that I am, consciously or unconsciously, punching faster and pulling back more swiftly with the snap punch than with the push punch, the latter which I expect to end its forward motion within the opponent before pulling back?

Honestly joesteph I don't know. My physics isn't that good . But I'd guess yes? If you liken the push vs snap to the thrust vs strike I think you could use similar arguments as in this thread. Personally I think the pushing doesn't strike as such but that you make contact and then apply pressure and keep driving forward with your mass rather than transferring the power in an instant. As a result it is slightly slower.

Does the snap with recoil encourage a faster punch? I'd go with tonydee's point:

Again, I think it's psychological: the anticipation of needing to pull back encourages a snappier punch, a tendency to speed up the striking contractions.

Either way the problem is more complicated than just snap or follow through. You need both but to varying degrees and us as human seem to have an uncanny ability of feeling the correct amount.

I'd agree with that. This is now starting to going way past my knowledge base.... was never too good at physics at school... although I do live with a physics postgrad so might go ask him later.

[sensei8]

Seems to me that everyone's forgetting about ones driving base: the front leg and the back leg while in a stance. What are those legs doing all the while when someone's executing, for example, a reverse punch? Crudely, their pushing/driving the body forward, which is helping to amplify that punch. Snap or follow-through are both still dependant on one of its crucial and important ingredient: the driving base.

We have to also appreciate that the difference between these two types of technique is not that one is done more quickly than the other and not that a thrust is held out while a snap is pulled back immediately. Realistically, because of the lightness that is inherent in snapping techniques they may well be quicker than thrusting ones but that should not influence the intent. Every technique in Karate should be intended to be as fast as possible.

That's why I believe that, while Kata is still very vital to the three K's, Kata teaches us to pose the technique(s) in a deliberate pause; this is wrong and this pose/pause makes that particular technique(s) in Kata totally ineffective! Not because I say so, but, because posing/pausing a technique(s) goes against natural laws and the like, imho.

Regardless of whether it’s a snap/follow-through (strike/thrust) with either the foot or the hand, for it to be truly effective and efficient the return course must also be the same. When we send out a punch with the elbow behind the fist we must take care that the elbow returns first with the fist following. This sounds to be very obvious, but, it's frequently not done. Therefore, if the kick/strike/punch starts its life out as a thrust it must return as one. So, if a technique starts out in life as a snap it must return along the same path. This makes it possible to have a relatively effective hit along the entire course of the technique and not just at the end.

Of course, without the hips, everything in the martial arts is quite mute!