In many martial arts we are taught that on the climax of our technique we should “sink” into our stance. I will admit that if my knees are sore, I sometimes find this quite difficult to do.
But firstly, why do we do it? “Sinking” at the climax of out technique is a way improving our skeletal structure and helping us for form an immovable “root” to the ground, thus enabling us to more efficiently absorb the reaction energy to any impact from our blows. Or more correctly, we don’t absorb the that reaction energy as it tries to go through our structure, finds the immovable ground, and is rebounded into our opponent again (so he gets it twice).
So why do a lot of people struggle with it?
Although you obviously have to bend your knees more in order to sink, if you focus on bending your knees then ironically it will probably not come easily. It’s a little bit like doing a squat, the more you bend the knees, they more you intuitively tense your legs to absorb the weight!
In some styles such (as in the early versions of Shotokan exported from Japan) there was an over exaggerated exhalation/tension in order to produce kime (focus). I remember being taught to tense the whole body including the legs, which will obviously make it them a bit more resistant to bend, in order to sink further.
Also, if you have knee pains, you intuitively tense the muscles around them in order to prevent your knee bones/cartilage/ligaments/tendons/etc from moving about too much (hence less pain). I know this from personal experience. But this tension makes it difficult for you to bend the knees more and sink.
The best ways to “sink” into your stance is by getting the right feeling rather than focusing on a physical movement itself, because focusing on physical movement tends to make you focus on muscles, hence – tension. Some say it is like “falling down a hole”, but obviously you stop yourself before going too far.
Different things will work for different people, but I’d like to share something that has worked for me.
We are usually taught in most martial arts to “breathe into your stomach” (or hara/dan tien). This is of course not actually physically possible as the air we breathe in goes into our lungs and can’t get passed the diaphragm to our stomach. Our diaphragm moves down and displaces our internal organs, so that it feels like we’re breathing into our stomach. In fact it’s a visualisation that we use help get the right breathing technique. It is however a very popular visualisation which most of us are taught right from the very beginning.
We can however build on this. When you want to sink in your stance as you exhale, try to visualise the breath leaving the stomach through the legs, to the feet and out into the ground. If you focus on the breath going down (rather than your weight going down), you should find it relatively easy to sink slightly without unnecessary tension. The whole process becomes much more relaxed and natural movement which is what we should be aiming for.
I actually learnt this through Tai Chi, but have applied it to my Karate. Of course, once your body gets used to the correct feeling, you can drop the visualisation as your body will know what you are looking for, but it is a useful tool to help get that feeling in the first place.