Shotokan Karate is one of the four major karates styles in the world, so many systems are derived from this style, and thus are contaminated with some very incorrect concepts. Thus, whether you study Shito ryu, Isshin Ryu, Kyokushinkai, or any system that has the Heian forms as a base, you probably are making the errors I am listing in this article. It doesn’t mean your karate stance is bad, it just means if you make a couple of tweaks you can make it better.
A good karate stance should be a perfect blend between mobility and solidity. Mobiity is when one can launch their body quickly in one direction. Solidity is when one can grip the ground with their feet and become virtually immoveable.
In the Shotokan kokutsu dachi stance, however, the ability to be mobile or solid has been compromised. If you study the feet you will see that they are pointing in directions that are more than ninety degrees apart. This means the stance can’t make up its mind whether it is supposed to be mobile or solid.
If the rear foot is pointing away from the target the major muscles are pointing away from the target. The foot being in the wrong position means that there is not going to be enough traction for the push. The leg being pointed away from the target means that the major thrusting muscles of the leg can’t be properly employed.
in addition, the hips will be angled improperly, and when one pushes with the leg there will be a ‘power leak,’ in the structure. That is to say that the hips will not want to support the entire weight of the push. This can be severe enough to tweak the back, and even (in extreme cases) lead to problems with lower spine.
To fix this stance all one needs to do is turn the rear foot towards the target to about 45 degrees or less. This will angle the foot for better traction, and set up the major muscles for the push when one launches the body towards the target. Of course, this is going to alter the basic nature of the stance.
Thus, when you turn the foot properly, you are going to have to figure out the angle of the hips, and set the weight more on the back leg. Doing this will set the body for maximum push, but shotokan instructors will resist this alignment of the body for one simple reason: it lacks shotokan power. But this means that the system has been corrupted for the feeling and sake of power, and not for the balance between grounding and thrusting.
To get past this, Shotokan masters have set the system up to rely on overly aggressive front stances. What they have done is okay, but only in specific instance, and the proof is in the fact that the kokutsu dachi stance is more for rooting than for shooting. Thus, you have a choice at this point, do what you are told in Shotokan Karate, or other classical martial arts styles, or analyze the physics I have presented here and alter your stance in accordance with these physics.
If you are interested in learning the correct physics of the martial arts you should drop by Monster Martial Arts.