In this paper the topic of how the negative portion of the body, meaning the portion of the body which is not directly connected to the arm or leg performing the technique, contributes to the overall karate movement in several different ways will be covered. The term “portion” as it relates to a section of body was chosen over “side” because the upper and lower body can also be considered “negative” when performing kicks versus punches, strikes and blocks, respectively. This paper will focus on how the negative portion of the body affects the generation of force and to body positioning.
In Shotokan karate one of the primary goals is to generate the most force with the least effort. There are many ways in which high levels of force can be achieved, with varying amounts of effort required. Some karate-ka can generate force through the application of brute strength (but with a lot of effort and slowly), and some can with blazing speed (but usually lacking power); however, these usually are not the most efficient ways to create extremely high levels of force. Speed, or acceleration, improves through relaxation and utilization of the appropriate muscle groups at the correct time, and by combining that with one’s whole body, not just the appendage performing the punch or kick, the karate-ka can maximize the force output with minimum effort.
In its simplest form force is equal to the product of mass and acceleration. Acceleration is a component of force that with diligent training and time should continue to improve, thereby contributing in a positive way to the overall force being generated. While no one can instantaneously increase his mass (weight) beyond his current value, he can utilize less than his total mass at the completion of a technique. So, at any given point in time, a karate-ka has achieved a certain level of acceleration and has a fixed upper limit to his mass. Therefore, at this given point in time, with the acceleration component a fixed value, in order to maximize force generation the maximum amount of mass has to be utilized (applied to the technique).
So what are the things a karate-ka must do to ensure they are utilizing all of his potential mass? One thing is to fully engage the negative portion of his body. Take, for example, a chudan oi mae geri over a medium range and that it is being executed by the right leg. The upper body and lower left side are the “negative” portions in this example. Without getting into the details (and the physiology) of what makes up a good mae geri, suffice it to say that in this example the right leg is moved forward (it starts out as the back leg) and is lifted (with the knee bent) prior to the lower leg being extended and contacting the target with the koshi. The left leg and upper body have a direct and dramatic impact on the overall resulting kick.
Starting with the upper body in this example, in order to not reduce the mass component of the force equation, the upper body must move in the same linear (and horizontal) direction as the right leg. By keeping the abs and torso taut, the tanden curled under and forward, and the hips and shoulders in alignment, the upper body will be effectively utilized in the kick by having its mass moving forward and being firmly connected to the lower portion of the body. This ensures that the center of gravity of the karate-ka is in front of them, moving in the direction of the kick and the target.
Figure 1: Proper Mae Geri. Note position of shoulders in relation to the hips, left leg is bent and foot is flat on the floor, right leg and koshi are extended.
However, if the karate-ka leans backward as the kick is raised and executed, then the mass of the upper body is moving in the opposite direction of the kick thereby reducing the overall mass applied to the kicking technique. As a general trait the upper body weighs at least as much as the lower body, if not more. Therefore, by leaning back, the karate-ka’s center of gravity may be moving backwards (or at best be stationary) away from the target. Not only does this reduce the total force potential, but it also has left the karate-ka with poor body position. Forgetting force for a second, by leaning backward, the karate-ka now has a harder time snapping his kick back and has to take time (and effort) to lean forward in order to correct his center of gravity (move it to his center or in front of himself) in preparation for his next movement or technique. Moreover, the tanden and torso are not effectively used and connected to the lower body. This can result in the karate-ka being pushed backward when his kick impacts the target, rendering his kick virtually ineffective.
The left leg plays a significant role also. Because it is the support leg in this example, it does not move significantly (a great distance anyway) but it does move. And as long as it is moving forward (in the same linear direction as the right leg) it is positively contributing a portion of its mass to the overall total. Assuming the left foot stays firmly and flatly on the ground, and the left knee moves forward (horizontally) slightly while maintaining the same amount of flexion, and the left hip does not fall behind the right (twisting of the hips with the right in front), then this “negative” portion of the body has also had a positive impact on the kick.
Figure 2: Improper Mae Geri. Note shoulders are behind the hips, right hip is infront of the left, the left leg is straightened and left heel is raised, koshi of right foot is not extended.
However, if, say, the left knee straightens, then direction of the force now has a vertical component as well as a horizontal, making the distance the kick travels longer and alters its direction. This results in less mass moving directly at the target (which is optimally at 90 degrees to the target’s center vertical axis), and instead moving at the some less-optimal angle. Therefore, the force and power (power = force X distance / time) outputs of the kick have been effectively diminished. Moreover, by straightening the left leg, effective body position has been reduced. By changing his vertical height during the kick, the karate-ka has increased the visibility of his movement, taken extra time and effort to move up and down, and reduced the stability of his stance.
Hip position plays a vital role in this kick as well. If you divide the body along its vertical axis into the right and left halves, then you can see that any twisting of the hips along this central axis will cause one half of the body to move forward while the other half moves backward. That being said, keeping the hips full-faced in the direction of the kick, the forward movement of the left leg means that both hips move forward the same amount. And as previously stated, if the upper body is in the correct position with the tanden and torso taut, then the upper body moves forward as well. This hip position allows the most mass to be used in the execution of the kick. If the hips are allowed to rotate, with the most likely scenario having the right hip moving forward and the left backward, this causes twisting around the vertical axis, reducing or eliminating any forward movement of the upper body. Body position, or more precisely, the path the body (the kicking leg specifically) takes when the hips are rotated during the kick will be more circular, starting right and going towards the left as the right hip goes forward. And while a somewhat circular kick may still find a target, a straight kick will get to its target faster, thereby increasing its force and reducing the chance it could be blocked.
There are many other karate techniques which have similar requirements to the oi mae geri as far as the “negative” portion of the body goes and the generation of force and body position. And its not limited to offensive techniques, it applies equally as well to blocks and to just stances (as in tai sabaki without a block or counter). Understanding the role, purpose and impact of the “negative” portions of the body will help reduce the effort and increase the power and speed of the techniques for the karate-ka, resulting in increased force and better body positioning. As an instructor or coach, demonstrating to and correcting newer karate-ka on how to fully engage the negative portion of the body is a lifelong goal or journey in Shotokan karate. Finally, as a karate-ka, engaging the negative portion of the body in every technique during kihon will lead to more powerful kata and effective kumite.
Craig Lawton
Triangle’s Best Karate
January 13, 2008
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