Using Forces to Understand and Explain All Physical Methods

'What are the forces involved in a straight arm lock?' - this was a typical question asked by Jan de Jong in the theory examinations in his jujutsu dan grades. Unbeknown to himself, De Jong was using the mechanical concept of force to understand and explain his joint-locking techniques (kansetsu waza). If the mechanical concept of force was understood, the answers to these types of questions would have been more succinct, focused, and accurate.

In the blog before last, I demonstrated the ubiquitous nature of forces within the physical methods taught in the martial arts and those used in violence generally. Rather than just asking what are the forces involved in specific joint-locking technique, the same question could have been asked of all the physical methods taught within all martial arts and used in violence generally.

Recall that a force acting on a body or object can deform the body or object, change its state of motion, or both. Injury is defined by the Committee for Trauma Research as the deformation of tissues beyond their failure limits. So, a force acting on a body can deform the tissues of that body beyond their failure limits resulting in injury. A force acting on a body can cause injury.

Changing the state of motion of a body or object refers to mechanical acceleration. In mechanics, acceleration refers to something starting, stopping, speeding up, slowing down, or changing direction. So, a force acting on a body can cause it to start, stop, speed up, slow down, or change direction.

Kreighbaum and Barthels, in Biomechanics: A Qualitative Approach for Studying Human Movement, suggest that 'because forces account for the motion and changes of motion of all things in the environment, including the body and the body segments, it is important for the movement specialist to understand what forces are and how we can picture them as they are applied to or by a body.' Because forces account for the changes in motion and deformation of all things in the environment, it is very useful for the martial arts instructor and student to understand what forces are and how they can be visualised as they are applied to or by a body.

The beauty of using this far reaching concept to understand and explain all physical methods taught within the martial arts and used in violence generally is - it is a relatively simple concept to understand and apply.

A force is a push or a pull.

It does not get any simpler then that. Everybody can relate to this concept. There is a bit more however.

Note the reference to a force. A force is thought of as a specific action in mechanics. It is a push or a pull. A single force can act on a body or object, or a number of individual forces that can be clearly distinguished can act on a body or object.

A force requires the interaction of at least two bodies and/or objects. A force acts on a body or object. That is to say, pushes and pulls are applied to something; and from that something's perspective, it has a force exerted on it. Forces do not exist in isolation from the body or object experiencing them.

Forces can be classified as contact and noncontact forces. Most of the forces we think about are contact forces. These occur when the bodies are touching each other. Noncontact forces are forces that occur even if the bodies are not touching each other. The primary noncontact force of interest when dealing with physical violence is the force of gravity.

Pushes and pulls are thought of as general actions rather than simply pulling something towards something or pushing it away from something. For instance, Kreighbaum and Barthels refer to blows or impacts as being examples of forces that they explain can be thought of as a push or pull.

In Basic Biomechanics, Hall explains that each force is characterised by its magnitude, direction, and point of application to a given body. So, in addition to whether or not the force is a push or a pull, we also need to describe its magnitude, direction, and point of application to fully describe that force. That's not so much, is it?

Jigoro Kano, the founder of judo, describes the basis of kuzushi (unbalancing) in Kodokan Judo: 'The basis of kuzushi is pushing and pulling.' A force is a push or a pull. Kano, the original martial arts biomechanist, conceives and explains kuzushi in terms of forces.

Forget the convoluted explanations of unbalancing methods. A push and/or a pull is applied to an opponent in order to unbalance them. End of story.

Bruce Thomas, in Immortal Combat: Portrait of a True Warrior, states that kuzushi 'cannot be rationalised, only felt or sensed through sufficient practice.' In Mastering Jujitsu, Gracie and Danaher, when discussing kuzushi, suggest 'it is difficult to teach in words, and it must be experienced to be really understood.' How difficult is it teach that a push and/or a pull is applied to an opponent in order to move their centre of gravity outside of a base of support which unbalances that opponent? Is that not the very definition of a rational explanation?

Maybe it's as Neo explains in Matrix Reloaded: 'There are only two possible explanations: either no one told me, or no one knows.'

The basis of all physical methods taught within the martial arts or used in violence generally is forces. Kano only used forces to understand and explain kuzushi. Sacripanti has used torque, the turning effect produced by forces, to develop a logical, objective classification of judo throwing techniques. This classification remedies the deficiencies inherent in Kano's classification, which is still used today, and the other alternatives that have been developed in response to dissatisfaction with Kano's classification. All physical techniques taught within the martial arts can be better understood and explained with reference to the mechanical concept of force.

Next time you look at a technique, any technique, think in terms of forces. Forces account for all changes in motion and all deformation. What is the intention of the application of the forces onto an opponent? Is it intended to change their motion or deform their bodily tissues, or both? Is the force applied to the opponent a push or a pull? What is the magnitude, direction, and point of application of the applied forces? There is more, which is covered in the books I'm writing, however this is sufficient to get you seeing the basis of all the physical methods taught in all the martial arts or used in violence generally.

It does become a little like swallowing the blue pill in the Matrix. You will come to see things differently.