I am really jealous of Usher-san's great posture. If he has to break his posture to do something then he doesn't do it. I saw a video of myself doing a kata the other day and, though generally upright, I found a new place to watch out for my posture breaking. When I am backing up and hit a tension point - i.e. the bad guy stops my motion. On the tape it was pretty common for my butt to rock back out from under my shoulders for a second before I could get it back under control. I will have to watch for that.
In aikido, we often work on improving our posture. To attain and maintain better posture. This is not based on some aesthetic ideal of 'straightness,' but rather, better posture is more neutral and gives the martial artist better mobility and options. The ideal is to be able to flow and do all of aikido in or very close to a natural upright posture (shizentai). In aikido you cannot really separate the posture from the technique or the motion. Upright posture in flowing motion is the goal.
Below is a re-post of several of Feldenkrais' principles from his book, Awareness Through Movement, relating to the questions, "What is good posture?" and "What is good motion?" I like to keep these ideas in the front of my mind when I am explicitly re-working my posture in aikido.
- Effective action improves the ability of the body to act.
- Reversibility is the mark of [good] movement.
- Light and easy movements are good.
- There is no limit to improvement.
- Use large muscles for heavy work.
- Forces acting at an angle to the main path cause damage.
- Superfluous efforts shorten the body.
- Concentration on the aim may cause excessive tension.
- Performance is improved by the separation of the aim from the means.
- Lack of choice makes strain habitual.