The physics of a punch

[jetboots]

I have done lots of martial arts in my day. The other day I got into a conversation about punching technique. My point to them was that for a punch to hurt it's all about the snap back; try to pull back twice as fast as you came in.

But when I was thinking about the scientific reason for this, we (3 engineers) were not in agreement, and not really understanding why.

If you do a follow through punch, then your kinetic energy is transfered into deformation of the person's body, then into kinetic energy of their body moving.

However, if you did the snap back technique, the main question of dispute was if this was analogous to why whipping someone with a wet towel hurt, or wheather it was more to do with how nerves work (a sustained deformation hurts less?).

happy hump day.

[jread]

For a punch to hurt, it's more about punching "through" someone and twisting into it than snapping it. For instance, if you're aiming to punch someone in the face, you don't aim for their face, you pretend you are aiming for the back of their head.

In my years of both traditional martial arts as well as Muay Thai and boxing, this was the concept taught. I've never heard of the "snapping" theory.

[jetboots]

For a punch to hurt, it's more about punching "through" someone and twisting into it than snapping it. For instance, if you're aiming to punch someone in the face, you don't aim for their face, you pretend you are aiming for the back of their head.

In my years of both traditional martial arts as well as Muay Thai and boxing, this was the concept taught. I've never heard of the "snapping" theory.

I did Kempo as well as kung-fu and kick boxing, and this was always the case from what I was learning. Indeed you do aim behind his head, but once you get there, snap it back. From all my sparring experience this does hurt them more rather than turning it into a push. Also does not allow them to grab your hand, and also lets you punch at a faster rate. The follow through punches and kicks definitly have their place too.

[Zero Angel]

My father is an accomplished brawler, and he says 'hit through your opponent'. It would make sense that pulling back, and even the anticipation of pulling back by lowering your punching strength too soon would have a bad effect on your technique.

Usually its only professional fighters that are skilled enough to grab punches, so I wouldnt worry too much about snapping back to avoid that.

What i've noticed about fights i've seen and one fight that i've been in is that they usually end up as close up grappling/punching where traditional punching/kicking fighting doesnt work effectively. It seems more important in that case to perfect your blocking and grappling techniques.

Also, one important thing that my father taught me is that you should 'look like a fighter', doing shadow (mirror) boxing and form exercises where possible. I think that part of combat is a mind game, and that if you can intimidate your opponent, then you can lower his resolve to fight.

[SheepDog]

I've never seen the back part of the snap emphasized as you describe (not emphasized at all, really), but something like snapping on the forward part of the stricke was something that I was taught in one TMA class. The instructor was trying to emphasize how to get your whole body into it, with power coming from the feet, through the body, then into the strike. If you watch boxers, they transfer power from the feet as well, although I doubt they're taught to 'whip'.

Being generous, I'd say this is more of a teaching tactic. Being more skeptical, I'd wonder if that instructor was missing the point.

[cwazyonyx]

just for arguements sake, what if the longer you are in contact with the person's body, the more the energy you delivered with your punch is returned to you and shared; thus, allowing the effective force of your punch to be minimalized.

so possibly, the less time you spend in contact with their body, the more force their body is required to deal with on its own.

i don't necessarily buy that, but just a thought.

[cwazyonyx]

my physics teacher loosely explained collisions like this.

he said the object being hit should be like a wall (walls don't move for the most part when hit). then much of the force of the collision will be returned to the object that did the hitting. for example if you are rear ended, you can protect your self more by depressing your break throughout the collision.

if the object that is hit freely moves upon being hit, it behaves like a billiard ball in that it absorbs most of the force it was struck with.

[Sir Isaac Lime]

Bruce Lee made the "snapping" technique well known, demonstrating it by breaking a board freely hanging from rope.

One immediate way to increase your speed at impact is to "snap" or "whip" your hand just before contact. It is the same principle as the overhand throw. For example, if you throw a baseball with a full swing and snap your wrist at the last moment or the tail end of your swing, the ball will have more velocity than without the snap. Naturally, the longer swing with a snap will have more acceleration at the end than a shorter swing with a snap.

Not to make a conclusion though

[Hypnos]

My $0.02:

* You hit "through" an opponent or object to maximize momentum transfer. If you don't, you're working to arrest your own momentum before it's fully transferred.

* I'm not sure of the usefulness of snapping back except to prepare for the next tactic. Perhaps if you hit something soft, it prevents the deformed target from transferring energy back in to your fist, attenuating the shockwave you want built up in the target.

[coffeezombie]

* I'm not sure of the usefulness of snapping back except to prepare for the next tactic. Perhaps if you hit something soft, it prevents the deformed target from transferring energy back in to your fist, attenuating the shockwave you want built up in the target.

So snapping might work well if you're fighting a really fat guy?

I think those professional wrestlers are able to "hit" each other like they do because they do snap punches and not real punches.