What Physics Can Tell Us About Martial Arts

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(Inside Science) -- Jason Thalken has a Ph.D. in physics and also practices martial arts. He's the author of "Fight Like a Physicist: The Incredible Science Behind Martial Arts." A data scientist who works in industry, he has studied and competed in eight martial arts, and has a black belt in hapkido. His book investigates and discusses how fighters can use science to gain an advantage, why safety equipment can backfire, and why center of mass, pi, and momentum are all important to those who practice martial arts. The book is written to appeal to readers regardless of their scientific background. Fans of other sports, including football, will also be interested to read the chapters on brain injuries and concussions. Readers might not expect a martial arts book to discuss football, but to a physicist like Thalken, exploring the way safety gear, collisions, and technique influence brain injury makes a lot of sense.

Thalken talked to Inside Science's Chris Gorski. The transcript of the interview was edited for length and clarity.

Inside Science: Were you into science first, or martial arts?

Jason Thalken: I've been interested in science since I was a small child. But I didn't really start getting into physics until high school, college. The same thing with martial arts. I started with martial arts back in '95. It's really been a parallel path the whole time.

IS: Do you think that a physics background gives martial artists some kind of extra advantage?

JT: I would say I think a physics background would give an advantage. But it's probably not exactly the way people would think. It's not like drawing lines and making calculations about force and stuff like that are helpful. Perhaps the primary advantage someone like that would have is the understanding of being able to take your training for one thing and applying that into unknown [situations].

IS: In the book, you discuss how an individual can think about their own center of mass and the value of momentum versus energy when they're striking someone or being struck. Could you explain some of those main points?

JT: If you want control over your own stance and your own position then you need your center of mass above both your feet. We have all sorts of ways we can do takedowns, throws and sweeps, but it all boils down to a very simple premise. And that's moving the center of mass away from the supports [usually the athlete's legs], or moving the supports away from the center of mass, and then ensuring that your opponent doesn't make a movement to put their center of mass back above their [supports] and weight. I guess it's a relatively simple concept, but there's all sorts of different variations and different styles.

The range of available human motion is the dictating factor there. It's not the laws of physics that say you have to have either a high momentum or a high energy strike. If you're going to throw a punch you can have your muscles very loose, and in that case your body acts more like a bunch of loosely connected separate objects, but you can move very quickly. That puts very little mass behind it, but it can move very quickly. That ends up being a high energy strike, and it can cause localized tissue damage, something like that. It can hurt, but it's not going to knock anybody back, or rotate anybody's head and knock them out.

On the other end of the spectrum is if you actually tighten your muscles, or selectively tighten them, you can actually be one solid object at the moment of impact, and have a lot of your mass effectively behind that punch. That can knock an opponent back, or rotate their head and knock them out. So you end up with this dichotomy between the two, and those things usually don't end up being head to head, but they are for fighting.

Fighting, Safety Equipment, and Injuries

IS: And it seems like that kind of theme is carried throughout the book, especially when you talk in depth about the brain injuries.

JT: For a very long time the way we looked at injury and impacts was, we just took things like skull fractures, and said that a concussion is probably that to a lesser extreme, and just went with that. It turns out that that was not a very good idea. So instead, what we've done [with safety gear, including gloves and helmets], is we've reduced the ability to feel sensations of pain, for both football players and fighters. But we've enabled them to take large numbers of hits to the head. Big ones cause large rotations of the head, little ones cause small rotations of the head. There's shear forces applied along the axons [parts of nerve cells] in the brain. That ends up causing injury.

We don't see damage around the edges of the brain. We don't see damage localized to the front and back, we don't see radial patterns of damage. What we see is diffuse damage throughout the brain. We should expect to see [localized damage] if the brain was bouncing off the front and back of the skull, or side to side. And then ultimately, if that was what was going on, then for a boxer a straight punch to the forehead of the opponent, that would knock the brain right into the front of the skull. But that is not the knockout punch. What your knockout punch is, is a hook to the jaw. And it turns out that the jaw is actually the furthest distance from the point of rotation at the base of the skull. So that gives you the most leverage to get the head turning. 

IS: The potential exposure, the repetitive exposure to these kinds of injuries is huge if you're fighting competitively, but maybe also sparring very intensely. What kind of things do martial arts leaders need to think about changing in order to try to keep people in the ring and in the sports as long as possible? 

JT: There's a lot of things that we can do to try to mitigate that. One big one is actually just changing the way we think about safety gear.  We have this notion that wearing gloves is safe, and wearing bigger gloves is even safer. It comes down to the simple fact that that's only safer for superficial injuries. If we really want to protect the brains of our athletes, we should probably take the gloves off altogether. Obviously there's the potential for eye injury and [cuts, bruises, and broken bones], so there's other concerns, but if we're talking about protecting the brain, even if we're not going to make changes to the sports, take the gloves off for boxing and mixed martial arts, just training without the gloves would be a step. 

One of the things that boxing gloves and MMA gloves do is they provide a lot of protection for the hands. If you're not able to throw full force punches at your opponent's face and head without personal repercussion, that's a very different, you'll take a very different approach to your fighting style.

Training for the Known and Unknown

IS: In the book you talk about a different approach in training and competition, to try to not injure your training partners. Does training differently than you compete put people at a disadvantage in competition?

JT: There was a concept that was introduced, I think it was in Rory Miller's book, "Meditations on Violence." He said, if you're going to be practicing martial arts, no matter what there is a flaw in your training. And the reason for that is that if there was not a flaw in your training, you would be killing and seriously injuring people that you train with. There has to be an intentional flaw there. That's actually where I get into where you should [approach a problem] like a physicist would approach problems. You're not training for the specific scenario that you're looking at right now, you're training to tackle the unknown later on.

IS: It seems like the whole book is built around what's the evidence we can find and what's the theoretical basis we can find behind the martial arts. How many of the people in the martial arts world are tied up in concepts that cannot be proven, such as the concept of the metaphysical force known as "Qi"?

JT: There's one part of the book where I talk about not throwing away good stuff just because it has a mystical explanation. I think some pressure points are a really good example of this. I've personally been brought to my knees by having a thumb shoved inside of my elbow before. Of course the explanation for that is that my Qi has been affected. Just because the explanation is Qi doesn't mean that that didn't work. I wanted to write the book such that I wasn't just dismissing anything that had to do with Qi, but instead saying some of these things are things that we had to come up with an explanation for before we had the actual science to explain it. So we're not saying that it's all garbage, but we are saying that it's about time for us to come in and figure out what's really going on here.

IS: Is there anything else that you'd like to elaborate on? 

JT: A lot of people don't necessarily understand at first why a study of martial arts would lead us to answers about problems with football today. In football, you've got all sorts of different things going on. The actual activity that's causing the brain damage is not the primary activity that's going on. We're trying to get a ball in a certain location. That has nothing to do with brain damage. But, then you look over at boxing and MMA, then the actual goal of the activity is that brain damage. Then we can take a look and we can say, okay, what are these guys doing that's effective at causing that, and what's not? We really should look to a sport that's looking directly at causing what it is we're trying to fix. 

Thalken tweets at @JasonThalken