The photograph to the right is of a straight arm lock, also commonly known as an 'arm bar', and in Japanese as ude kujiki. The photograph is not the greatest, but it was taken at the late Greg Palmer's dojo with two of his former junior students. Greg was a senior instructor of Jan de Jong, was one of my instructors, had a depth of understanding and love of jujutsu possibly second to none at the Jan de Jong Self Defence School, and became a friend and training partner of mine. Out of respect and in memory of Sensei Palmer, I'll use this photograph for illustration purposes.
Jan de Jong included theory gradings in his dan (black belt) grades. These are oral gradings which examine the candidates knowledge of techniques and tactics, the proficiency being taken as given. If a black belt represents a teaching qualification, as it most definitely does in Jan de Jong jujutsu, the candidate's theoretical knowledge should most definitely be examined.
How do you study for this theory grading? Unfortunately biomechanics in biomechanical or martial arts texts will not be of much help. Vieten (2008) provides an overview of the English-language martial arts literature related to biomechanics. He found the percentage of biomechanics papers among the literature in martial arts is very low compared to some popular sports and suggests ‘the biomechanics of the martial arts is still in its infancy’ (562). Too true. My work is about growing that infant. This blog is about growing that infant, and possibly encouraging others more qualified than myself to take up the challenge.
Kreighbaum and Barthels (1996; K&B) explain 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 the body' (80). Firstly, 'a force is something that causes or tends to cause a change in the motion or shape of an object or body' (80). It's not just a change in motion which forces cause; they also cause a change in shape which is referred to as 'deformation' in mechanics. If the deformation of the body's tissues is significant enough, it will lead to injury. Secondly, given the preceding explanation of forces, it is important for martial arts instructors and students to understand what forces are and how they can picture them as they are applied to or by the body. The beauty of it all is that it is so easy - 'easy peesy Japanesey.'
'A force can be thought of as a push or a pull; ... a blow or impact, or gravity' (K&B 1996: 80). Forces have four unique properties: magnitude, direction, point of application, and line of action (K&B 1996). In initially answering our theory question, all we need to do is identify all of the points of application and describe their direction and whether they are a push or a pull. That is it - easy peesy Japanesey. Forces are what makes the technique work. They are the essence of the technique.
With the ude gatame ude kujiki, there are three points of application. The right hand is applying a pushing force to the back of uke's (receiver of the technique) flexed hand back towards uke; the left hand is grasping and applying a pulling force on uke's wrist away from uke; and the elbow is applying a downward force to uke's elbow. That is it - easy peesy Japanesey. Next question.
Firstly, it can be seen that kansetsu waza is a class of technique which overlaps with many other classes of techniques. It has multiple personalities. Secondly, so what? So what? The technique may look the same, that is to say it has the same points of application of the forces, but the direction and magnitude of the forces will differ depending on the purpose of the technique.
What is the physiological effect of applying forces to the extended elbow when executing ude kujiki? Here there is no authoritative answer. I was astounded, when researching the science behind joint locking techniques, that I could find no detailed explanation of the effects of kansetsu waza when forces are applied and the joint is moved beyond its range of motion. If any reader knows of such information, and only authoritative information is of interest, I'd appreciate it being forwarded to me and I will duly share it with the world via this blog.
Why not refer to medical or forensic texts? I did. However, between 80% and 90% of all injuries that occur to the upper limb are the result of a fall on an outstretched hand (FOOSH injuries; see http://http://www.kojutsukan.blogspot.com.au/search/label/FOOSH). Consequently, the medical and forensic literature focuses on these types of injuries. The forces are applied in a different direction when landing on an outstretched hand compared to when forces are applied at right angles to the posterior aspect of the elbow when executing an ude kujiki.
- posterior – the forearm bones are displaced posterior to the distal part of the humerusand accounts for the majority of all elbow dislocation injuries.
- anterior - the forearm bones are displaced anterior to the distal part of the humerus and are extremely rare. Consequently the data on these types of injury are likewise rare.
Anterior dislocations are often described as occurring when the elbow is flexed and it receives a blow. The olecranon can lever the humerus and slide in front of it, or, it can be fractured. This is often referred to as a 'fracture-dislocation'.
I apologise for not being able to identify the source of the following quote. It is included in my notes without reference, and I need to go back to my notebooks to identify the reference. However for the purposes of this blog I will proceed without the reference.
Given elbow dislocations are the one joint technique allowable in judo (wrist, shoulder, and knee techniques were forbidden due to the risks of injury associated with the techniques), a sport practiced around the world for a century, and there is no reference I can find in the literature on extreme elbow injuries as in the case of a fracture-dislocation in judo, I might hypothesise that the abovementioned dislocations without fractures are not uncommon when an external force is applied to the posterior aspect of the elbow.
The technique to the right is described as a 'step in arm lock.' Comment on the technique? This is a question which De Jong would often pose using photographs from books, etc? Firstly, a tactical issue. Stepping toward the opponent while applying this technique exposes the defender to the risks posed by the attacker's free hand. Secondly, stepping forward changes the forces applied by the hand at the wrist. Now it is pushing rather than pulling. This has the effect of 'close packing' the elbow joint increasing rather than decreasing its stability (increasing rather than decreasing its resistance to forces). Thirdly, I would hypothesise that should the combined forces result in a dislocation of the elbow, it would result in a posterior dislocation whereas when forces are applied to stretch the elbow joint and then forces applied to the posterior aspect of the elbow, they might result in an anterior dislocation and/or a disclocation-fracture.
*Interestingly, Jigoro Kano explains that 'the basis of kuzushi is pushing and pulling' (1986: 42). Kano, the originator of the use of biomechanics to understand and study the tactics and techniques of the martial arts - to a degree and possibly unwittingly.
Kano, J. (1986). Kodokan Judo. Tokyo: Kondansha International
Kreighbaum, E. and K.M. Barthels. (1996). Biomechanics: A qualitative approach for studying human movement. 4th edn. Boston, Massachusetts: Allyn and Bacon.
Vieten, M.M. (2008). Application of biomechanics in martial art training. In Handbook of biomechanics and human movement science, edited by Y. Hong and R. Bartlett. Abingdon, Oxon: Routledge.
Whiting, W.C. and R.F. Zernicke. (2008). Biomechanics of musculoskeletal injury.2nd edn. Champaign, Illinois: Human Kinetics.