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The Science of Jiu Jitsu

In this article, we look at the physics behind BJJ and demonstrate how the interplay of leverage, force and mass work together to create effective technique.
The Science of Jiu Jitsu

by JJB Admin

5 years ago

This article was written by Jiu-Jitsu practitioner and enthusiast Stuart Langley

The words jiu-jitsu come from Japanese, the direct translation is ‘the gentle art’ and the basic concept is to use technique to overcome the inherent advantages of size and strength.

When we are using jiu-jitsu we are looking to create an advantage where there is an imbalance between our situation and our opponent's situation. This might be by concentrating the force from multiple parts of our body on a single part of our opponent’s body. It might be by using the principle of leverage to multiply the force that we are able to bring to bear on our opponent’s body or it might be by using their biomechanics against them, for instance turning a joint in a direction it is not designed to move.

Over the coming months, my aim is to explore the scientific concepts behind jiu-jitsu to help you understand why certain techniques work and therefore allow you to focus on applying them in the most efficient way possible to deliver the end result of using your technique to overcome a larger stronger opponent. I will start off by defining some basic scientific concepts that underpin jiu-jitsu before discussing how they apply to different groups of techniques with specific examples of basic techniques that should form the backbone of any fighter's arsenal.

Traditionally, jiu-jitsu has been taught in a technique focused manner, each class the instructor demonstrates a specific technique step by step which everybody drills repeatedly with the instructor walking around the group giving feedback and correction. Good instructors build a curriculum that chains groups of techniques together and their classes over time build their students game by giving them multiple options from any given situation. More recently the focus for many instructors has switched to a principal based game. The idea here is that instead of just focusing on individual techniques, by focusing on basic principals for any given situation, the student has a more flowing open game, and is better able to react to novel situations and therefore be inventive in their jiu-jitsu. I think that both of these approaches are valid and have their place but what I want to do with these articles is look at the ‘why’ behind the principals. By truly understanding this, I think we can continue to refine the art and get closer to the ultimate goal of perfect efficiency. There are multiple branches of science that we can look at when investigating jiu-jitsu but broadly I will be focusing on 3: Physics, Mechanics and Biology.

For some of the concepts that we will look at it will be enough to think of the human body as just a simple lump of mass (the clichéd perfect sphere in a frictionless environment) however for many of them we will need to look at the mechanics of how our different body parts are put together and how they move. Finally, we will need to take it a further level to understand ourselves as a living organism to understand how our jiu-jitsu techniques can be used to disrupt the biological process that are going on inside our opponent.

Some Basic Concepts


Starting off in the world of physics our first building block of understanding is mass. Mass is defined as the measure of the amount of matter in an object and until someone opens the first academy on the international space station, the most common way that we are going to be thinking of mass is due to the way that gravity works on it. Gravity is one of the basic forces in the universe and here on earth, its effect is to try to accelerate our (and our opponent’s) mass towards the centre of the planet. Something that has more physical matter has more mass; literally, Roger Gracie at around 200 pounds has more atoms making up his body than Caio Terra at 122 pounds. They can both make your life a nightmare in a jiu-jitsu match but their different physical attributes mean that they will do it in a different way (having been under knee on belly of both of them at different points in my training career, I can tell you that neither experience was pleasant, but I would take Caio all day over another 30 seconds with Roger.) A big sorry to my American friends but in order to make the math simple, we will use the standard scientific unit of kg for mass (it's pretty easy to convert, 1 kg is 2.2 lb)

Speed (velocity)

We often talk about a small fighter using his speed to defeat a heavier opponent, but scientifically speaking, what is speed? Speed is the measure of how quickly an object is covering distance. If you divide the distance something travels by the time it takes to travel it, you get the speed. More scientifically, if we are talking about the speed of movement in a specific direction we refer to velocity. The units we use for velocity in the standard scientific notation are meters per second (m/s). (Again for my American friends, a meter is 3.28 feet).


Building on our concept of velocity, if we want to talk about the rate of change of velocity, we are talking about acceleration. If you are traveling in your car at 13 meters per second (about 30 miles per hour) and you hit the accelerator hard and 1 second later you are traveling at 18 meters per second (about 40 miles per hour) you accelerated by 5 meters per second (18 – 13) and you did it in 1 second, so we can say that your acceleration was 5 meters per second per second, or 5 m/s2.


The next concept I want to look at is Force. Force is the result of a mass being accelerated in a given direction (F = M A) what this means is that the force that an object feels is increased either when the mass used is increased (Roger vs Caio) or when the acceleration applied to that mass is increased (a punch has considerably more force than a push and a big dude punching you has more force than a small dude punching you. This is the basic reason why boxing and MMA has weight divisions). The basic unit of force is the Newton (Shout out to my homeboy Sir Issac), 1 Newton is defined as the force needed to accelerate 1 kg (2.2lb) by 1 meter per second per second. Just like in Star Wars, to be successful we need to become masters of the Force and in the coming articles I will help you understand how to do this.


No, we are not talking about what Putin has on Trump, that’s for a completely different article. What we are talking about here is the next base principal that goes to the very essence of jiu jitsu. ‘Give me a place to stand and with a lever I will move the earth’ Greek mathematician Archimedes of Syracuse was quoted as saying. A lever in combination with a fulcrum is quite literally a force multiplier.


A lever in its simplest form is just a simple beam or bar placed on a pivot point (known as a Fulcrum). There are actually 3 types of lever, and in a later article we will get into the differences between them and how that applies to our jiu jitsu but for now, what I want you to focus on is the basic rules of mechanical advantage. Where this magic happens is in the length from the fulcrum to the ends of the lever.

The two ends of the lever effectively move in a circle around the fulcrum and the longer the distance from the fulcrum to the end of the lever, the faster the end has to move. The effect of this is that the ratio of the lengths from the fulcrum to the two ends (a and b in the diagram above) is the inverse of the ratios of the forces felt at the two ends FB/FA = a/b.

What does all this mean for your jiu-jitsu game?

Putting it very simply, if you want to increase the force that you are applying to your opponent, instead of just pushing harder, look for ways to lengthen the lever. To put this into a very practical example, when I am going for an armbar, what I am doing is turning my opponents arm into a lever with my legs as the fulcrum. If I try to finish the armbar by pulling close to his elbow, I will need to use far more force than by lengthening the lever and pulling at his wrist. In the example below, by moving my hands to my opponent’s wrist I have doubled the length of the lever. therefore for the same amount of force exerted by me, I have doubled the pressure that he is feeling in his elbow joint.

Armbar - Short Lever
Armbar - Long Lever


To give a second practical example of leverage in action, if I am in side mount I might feel that I am controlling my opponent more strongly by bringing my knees close to his body and gripping him tightly. But what I am actually doing is bringing all of my mass close to him, making a short lever and reducing the force needed to reverse me.

If, instead of this, I make myself long, sprawling my legs back and spreading my mass over a longer lever, I make it far harder for him to just muscle me over. I have made my lever 2.7 times longer increasing the force he needs to use to muscle me over by 2.7 times. In this example I am simplifying the model and assuming the mass is concentrated at the end of the lever, in reality, my mass is distributed through the length but the principle still holds, by sprawling my legs I increase my stability and make it easier to maintain the position.

Sidemount - Short Lever
Sidemount - Long lever

These are just two examples but the concept of leverage applies to pretty much every jiu-jitsu technique. A basic rule of thumb that I have heard repeated by many experienced instructors is that if it feels like I am having to apply a lot of force, I am probably doing the technique wrong. One of the first things that I do in this situation is try to think through what parts of me and my opponent’s body are acting as levers and focus on lengthening the levers that are working in my favor and shortening the levers that are working against me.


In this article, we have introduced some basic principals (mass, velocity, acceleration, force and leverage) and looked at how the concept of leverage can help us get a physical advantage over a stronger opponent. In the coming months, I plan to delve deeper into the science of jiu-jitsu to help you in your training. I’d love to hear your thoughts and questions in the comments section below. Jiu-jitsu truly is the martial art of the warrior nerd!

1 comment

  • Thank you so much for elucidating some of these principles. Has a follow up been published yet?

    Simon Wilkinosn on

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