One issue which I feel is often under addressed by many martial artists is the use of pseudo scientific concepts, however well intentioned, to explain simple physically relationships and laws. As a physics teacher I know full well the massive range of misconceptions even outstanding physics students often have until they are forced to readdress their understanding to reach a higher level of understanding further down the line.

It is for the exact same reason why I feel we cannot hide behind the excuses that science is difficult, or I don’t know where to start because the truth is by challenging our thinking we deepen the pool and we remove limitations. Physics is powerful. It applies to every situation and interaction; it is after all the study of physical reality. For this reason you can apply the fundamental principles to multiple points and unite your understanding within a common framework.

It is the greatest form of flattery that we mimic our teachers. Martial arts developed from practical and visceral experiences and so the pedagogy of martial study replicates this. Teachers often give instructions to create feeling. They demonstrate the technique and the feel of the technique and you repeat and through repetition and fine tuning your intrinsic feedback allows you to feel the technique for yourself. You know when it’s right and you definitely know when it’s wrong. And this works, in fact if you aren’t paying detailed attention to the intrinsic feedback you get when you are training you are missing a massive trick, however if you understand precisely what you’re looking for you will more readily be able to adapt and refine your technique.

Because of this legacy of feeling, the language that is often used is inadequate given rigorous consideration. Teachers fundamental goal is to help you improve but misuse of terms such as “power”, “force”, “impact”, “pressure” and the list goes on and on is not just poor practice but is damaging to a students detailed understanding of their techniques. Each of these words is a concept unto themselves so they should not be flippantly substituted. What is worse is many teachers invent truly nonsense phrases to describe an action or feeling they don’t fully understand. I don’t want to quote and embarrass any specific example so I’m just going to invent one for the purpose of this point lets just call it “wave action”.

This is me hitting someone without “wave action”… and this is me hitting someone with “wave action” (don’t forget the cheesy voice you should read this with, maybe even a head waggle).

The problem is often the phrases they use have some tenuous but limited validity for example, waves do indeed transfer energy and momentum however energy and momentum are two very different concepts with very different effects (a story for another time but in the mean time you can always watch **Backfist like a Bushi**). So actually this inaccuracy is uphelpful in developing a deep understanding of how the technique *actually* works.

So taking all this into consideration what should we understand more.

Mass! Specifically ** Effective mass**.

Your body has a fixed combined mass. In the United Kingdom the average mass of an adult is 70kg. Mass is important because when we perform any action onto or with our opponent we exert a force. Force is a very profound concept which few people really understand. For reference here are Newton’s 3 Laws of Motion.

An object a rest or in uniform motion will remain in the same state of motion until acted upon by an external force.

Force is directly proportional to rate of change of momentum.

If object A exerts a force on object B, object B will exert a force which is equal in magnitude, opposite in direction and of the same type.

So if you’re not a physicist lets simplify these into something meaningful.

1. Newton’s 1st Law… the law of balanced forces. It tells you what happens when all the forces are on an object are balanced… nothing! It either wont start moving or if its moving already will stay at the same speed.

2. Newton’s 2nd Law… the law of unbalanced forces. It tells you what happens when there is a resultant force… 4 options, objects will undergo an 1)acceleration 2)deceleration 3)a change in direction or 4)a change in shape. This can be represented by the following equation.

**Force = mass x acceleration**

3. Newton’s 3rd Law… the law of pairs. Every action has an equal and opposite reaction… there is no such thing as a free lunch.

We can discuss a myriad of applications of each law within martial techniques but for the purposes of this discussion I want to focus on Newton’s 2nd Law and the equation F=ma. What this equation means is that in order to exert the maximum force during a strike I need to consider the mass behind the technique and the acceleration. Acceleration is perhaps initially more obvious and easy to understand. Acceleration is the rate of change of velocity (speed with direction) which means if I need to accelerate your fist as quickly as possible at your opponent you will increase the force you strike with. However there is a major drawback here, do not confuse the force you exert on your opponent and force your muscles exert on your limbs to accelerate your body. The relationship between mass and acceleration is what we call inversely proportional. What this means is that if you imagine you can exert a constant force of 1000N, you could do this with either a big mass and a small acceleration (200kg x 5m/s2) or a small mass and large acceleration (1kg and 100m/s2). In other words as mass goes up, acceleration goes down and visa versa. So if you compare two people who can for argument sake both exert the same force via their muscles but one has a big mass and the other a smaller mass, the person with the smaller mass will be able to accelerate faster. So each person will have a limit to what they will be able to accelerate their body during a strike etc but of course you can seek to develop this in your training. What is less obvious is how you can increase your mass.

Part of the reason is you may immediately think, but wait I have a fixed mass (70kg average) which is true as far the ground is concerned. However when you strike you need to put as much of your mass behind the strike as possible, so even though your *total mass* is may be 70kg your *effective mass* may only be 5% of that if you are already striking successfully.

Let’s break this down.

Imagine if I chopped off your hand (in a humane and caring way). With the severed appendage I can then proceed to throw it back at you (just to add insult to injury). Your hand probably has a mass of about 500g or 0.5kg. If I throw it with an acceleration of 20m/s2 (ignoring air resistance) it will probably hit you with a force of about 10N. Not what I think we’d consider a devastating technique. Well let’s now chop off your arm. The mass which hits is going to increase and hence the force.

Now from a practical sense I don’t need to chop anything off (thankfully!) What I need to do is strike with the combined mass of my fist and my arm. Then let us add the mass of the shoulder, and then the torso, hips, even legs. How I hear you cry, well it all comes down to your bodies amazing ability act as both a rigid object and a series of floppy bits with smaller rigid bits.

Time for an experiment, you will need a partner. Stand feet shoulder width apart and lock your arm out in front of you, in fact lock your whole body. Then get your partner to push your hand. You should find your entire body moves. Now relax your wrist, elbow, shoulder and hip. In this situation you should find that your opponent can push and move only your hand but that the rest of your body should remain stationary. So through muscular contraction we can control the proportion of our body which can act as a unified *effective mass.*

So in order to increase the effectiveness of our strikes you must increase the effective mass you use behind it. This is a fundamental martial principle and is what makes martial arts effective as oppose to just being a brute who can hit things. Through the development of technique a smaller person can learn to use a higher proportion of their mass and hence improve the effectiveness of their strikes and even throws. The goal is to achieve the highest possible effective mass through muscular contraction at the moment of impact. For reasons we discussed earlier in order for you to move smoothly and quickly you want the exact opposite, you don’t want to move as a rigid object… higher effective mass, hence harder to accelerate. This is the true meaning of Kime.

Kime was first explained to me as the “snap” in the technique (which of course is muchiken) which although this did help in developing the feeling for Kime it was clearly limited in helping me develop deeper understanding. Further consideration should be given to Kokyu (breathing). As you exhale you tighten your core muscles and cause your torso to act as a unified mass so as well as working the connections of the body unify this with your breathing. Add to this correct timing to execute your strike at the optimum moment you will massively increase the effectiveness of your strike.

Now you need to think about all the implications effective mass has on your training. Consider grappling as an example that may appear distinct from striking but remember this is a principle and so is true regardless of the situation. If as you move in a relaxed way your opponent will find it difficult to move your entire mass in breaking your balance because (put simply) the force they exert at their point of grip will not be effectively transmitted through each movable and pliable joint. If they do suddenly catch you one of the simplest defences is to contract your whole body to act as one rigid mass since mass is inversely proportional to acceleration this should disrupt your opponents technique forcing an adjustment and buying you valuable time. Make sure this moment of rigidity is just that a moment, kime, otherwise as rigid body once your centre of mass is moving you become vulnerable once more. Hence exercise the rhythm of no rhythm.

Final health warning and advice – first you will notice I have avoided the word “weight” like the plague for this article. You should too. Weight is useful but it’s a different concept. Weight and mass are not the same thing, even though in our everyday we often mix them… “I’m going to weigh myself” well if it’s in kilograms, your measuring your mass.

The best thing to do is to open the conversation, discuss effective mass with your training partners, share this with them, discuss it and collaborate to develop your understanding. It will be time well spend and the implications on your training will be massive…

… yep ended on a pun.