Friday, September 29, 2017

Bad Science: book reviews and snappy punches

Sometimes people say things that are just so dumb I have to speak up. This is one of those days.

I've been reading more books than blogs lately, largely because the well of information in blogs has sort of dried up. Lots of people blog great basic fitness information, and I found that hugely useful to me personally ten years ago, but the market has reached a saturation point, and my favorite fitness bloggers talk more about business and motivation than about physiology, and that's not where my interest lies (which is not to say there's anything wrong with business talk, only that it's not what I personally care about).

I'm interested in martial arts history, at least to some extent, but my real passion (as is probably obvious to anyone who reads this blog) is application of modern science to martial arts training.

So I picked up a couple of books simply because their titles popped up on Amazon and they seemed appealing: Karate Science and Fight Like a Physicist. I had no previous experience with either author, and still don't.

Before I continue, let me just say: both books are worth a read; Fight Like a Physicist is significantly better (more clear, more correct, at least as far as I can tell) while Karate Science is less clear, but makes recommendations that are more interesting (possibly because they aren't clear) and therefore in some way is more thought provoking. But neither book is a must read (I doubt any book on the market qualifies as a must-read for a karate practitioner, at least in my opinion, unless your style's founder or your instructor has published a book. But that's a debate for another day).

A topic that is covered in both of these books, and that seems popular in martial arts forums (I've seen it asked often) is the difference between 'snappy' techniques and 'thrusting' techniques - why strikes are sometimes more 'snappy' than 'pushy', how to do one or the other, which one is better, how can we train to do one over the other, etc. If you're not sure what I mean, find a heavy bag. Jab it as hard as you can, and see what it does. Then stick out your arm and give it a long, hard shove. I bet the bag will move a lot farther with the shove than with the jab, but I bet you know intuitively that jabbing someone hard will hurt them a lot more than a long, hard shove (unless they're standing at the edge of the cliff).

 A fast jab and a shove are opposite ends of the spectrum, but we have all seen people whose punches are much more like a shove and others whose punches are more like a jab. I've also seen various martial artists say that snappy techniques are better, and thrusting techniques are worse. Some say that each type of technique has its place (I lean in this direction - sometimes you want to just hurt someone, sometimes there is value in moving them, even if by doing so you hurt them less).

Both of these books deal with this topic. The treatment in Fight Like a Physicist is, I think, exactly correct, in pretty much every way. I won't reiterate it fully here, but roughly speaking, snappy punches are faster but involve less mass, giving them relatively more kinetic energy but relatively less momentum (kinetic energy is proportional to the square of velocity, momentum to the velocity). Thrusting strikes are slower but involve more mass, giving them relatively more momentum and less kinetic energy. The more kinetic energy, the more damage you'll do (energy is, literally, the ability to change things). The more momentum, the more you will cause the target to start moving. So a faster technique will hurt more; a technique with more mass behind it will cause the target to move farther.

This is all based on very solid physics - this isn't advanced physics, we're talking 101 level college course at most, maybe a solid high school class. These are very basic principles of mechanics, though they usually aren't applied to martial arts. If you don't agree with this stuff, please do me a favor and take it to your high school physics teacher and ask.

What you shouldn't, ever, do, please, is read Karate Science and pay attention to its analysis of snappy punches. I'll quote out of a description of snapping strikes on page 199 and 200 of the book (bold face is mine):
According to physics, when you push against a wall or hit a target (action force), the target will push back into you with an equal amount of force until either the force applied stops or either side gives way. In addition, it can take time to transfer that action force, and for the object getting force applied to it to transfer that force back into the force applier (reaction force).
In these techniques, the limb penetrates the target, pushing through the soft tissue layers, then immediately retracts before the opposing body applies reaction force to the attacking limb
No. No. No.
Reaction forces DO NOT TAKE TIME. When you jump, you push down against the floor. There is no delay while the floor waits to push back. I don't mean there is a very small delay - I mean there is NO delay. The forces are simultaneous. Exactly simultaneous. There is no equation in any physics textbook anywhere to measure the delay before a reaction force is applied to an actor. BECAUSE THERE IS NO DELAY. NONE.

Retracting a technique quickly will NOT transfer extra energy into the target and prevent the attacker from having to handle reaction forces. The only way to lower the amount of reaction force you have to deal with is to hit with less force. You can't outrace reaction forces, you can't be so fast that the reaction forces don't have time to get to your hand before you've retracted your fist (though that sounds like a good topic for a Master Ken video or a martial arts anime. Maybe Son Goku in Super Saiyan Green form can punch that fast).

J.D. Swanson, according to the amazon author page, holds a PhD in integrative biosciences. I'm sure he knows a lot more about a lot of things than I do or every will, but those paragraphs are pretty inexcusable.

The point?

It is absolutely worth understanding the different qualities of a strike - whether a way of striking generates relatively more kinetic energy, relatively more momentum, or both. And it's absolutely worth understanding the right time to use techniques of different sorts - a great example is a teep in Muai Thai, which is a pushing front kick that is designed to create distance and push the opponent across the ring (it's a thrusting technique, but it's done purposefully to be a thrusting technique).

But if you don't really understand the reasons behind techniques, making up explanations is a bad way to go. You lose credibility with any students who took and understood high school physics. You look bad to any educated readers who might have otherwise been interested in a scientific approach to martial arts.

And, if you don't apply basic scientific knowledge and critical thinking to some of the claims you're making, you risk making really bad mistakes. Maybe you'll focus too much on retracting techniques (thinking you can actually outrace reaction forces!) and rob your strikes of power they could really use (there's a good reason to retract strikes quickly, but pulling your fist back fast doesn't make the punch harder, it just makes your arm harder to grab after the punch).

There is some interesting stuff elsewhere in that book, but it's really hard for me to take it seriously, especially the things that aren't obviously true, because the author has established a propensity for making really bad basic errors.

I promise I will not spend the bulk of my posts here being curmudgeonly!

Train hard. Osu.

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