One thing that I noticed about Kishaba Juku is how students are introduced to the concepts around koshi, whether or not they realize it, from day one. Whilst in most schools or clubs you have to do your time before you get a chance to feel or experience it. It is almost as though you aren't good enough to be given the opportunity to really experience those concepts until you have at least three or four years of training and experience. Also, the concepts are not really discussed or trained in to you. It is assumed that if you do your training that you will automatically get it with constant practice. That's one of the strengths of Kishaba Juku and what makes it special. The concepts are not taken for granted and they are an important part of the day-to-day training.
   I think that it takes forever to perfect the concepts around koshi. Even if you have it, it's noticeable that if you take it for granted you have to start working at it again. The concepts are also very difficult to explain and to show and teach to others. Particularly, the combinations within single moves like a simple upward block and the use of multiple muscles in your body concurrently or in sequence such as in an ordinary low block. It does take years to train those muscles to do what you need them to do and if you stop training it deteriorates. How can it not deteriorate when you have to build up those rarely used muscles all over again and you have to train your brain to activate each muscle in the right sequence and with the right timing.
   For the engineers and scientists amongst you, some of the muscles you squish to store potential energy and as you move they unsquish and add a bit more energy to your move. Similarly, you can swat to maximise the kinetic energy. The automatic unsquishing, swatting, and timing that gradually improves through training can generate an energetic rubbery kick from the potential energy that amplifies the swat. It's a devastating combination of body mechanics, electricity, circular and/or helical motion (mostly from hips, shoulders, limbs, and fists) for the maximum exploitation of potential and kinetic energy. In addition to this the core of koshi can be strengthened through co-ordinated breathing and regular training so that it becomes more and more like the centre of gravity of a gyroscopic system.
   Trying to understand how to do each move properly is addictive. When you operate the right muscles in the right sequences and with the right timing the feeling is amazing and you have all the power and speed that you need whilst operating in relaxed energy-conservation mode. It's like Karate with something better than Duracell batteries (maybe a good name for them would be Zen batteries) because you just keep going and going and you have all the power you could possibly need and you never feel tired. What's even better is that you don't have to restrict the concepts just to Karate since you can use them when swimming, cycling or running or in anything else that you do. You also acquire an ability to see it when it's in others and in the world around you.

Yours faithfully,
Mike Pagomenos

P.S. Read about Koshi as explained by a teacher in this short blog article called "Koshi - No Koshi"