As promised to Steve here is my attempt at correlating how this wonderful martial art can impact or contribute to ones understanding of karate.
As mentioned I graded nidan while living in Japan but really still consider myself just a beginner, there is so much depth to Iai that, like karate, it is an art that can be done well into old age.
For those not aware of what Iaido is, the short version is "the art of drawing the sword", the longer version can go on for pages but in my words it is the "skill in drawing the sword, using it immediately and decisively to end conflict". Many people train in Iaido as a supplement to other training (kendo, aikido etc). Further, there is no 'kumite' involved, if I can make a correlation, Iaido is kata and kihon, while for kumite one would have to do either kendo or kenjutsu.
There are currently round about 10 major schools ( with many variations just like karate) and the two most popular being Muso shinden ryu and Muso Jikiden eishen ryu. The art is as old as sword fighting itself, however, most agree that Hayashizaki Jinsuke Shigenobu, fathered 'modern' Iaido in the early 17th century.
Not to go into too much history but there are quite accurate (supposedly) records detailing Iaido masters all the way back to Shigenobu. As mentioned, the two most popular styles being Muso shinden and Eishen, with Muso shinden the 'younger' formulated in the early part of the 20th century (by Nakayama Hakudo) as a combination of Eishen and Tanimura ryu in the early part of the 20th century. Some use this argument to say therefore that Muso shinden is inferior ( insert any number of 'tradition vs evolution' arguments, just like karate).
I trained during my time in Muso shinden and had admittedly, very little exposure to Eishin besides a short demonstration. So I wouldnt like to comment on the technical aspects or dissimilarities. Again though I can imagine that it would be the same as between Shotokan and Goju, same basic techniques but different focus and outlook.
Iaido practice, I found, was 90% focussed on their 'kata' with only about 10% on 'kihon'. The kata are broken up roughly into 3 groups; seated, kneeling and standing forms and are rarely longer that 5 or 6 movements long. For the most part you have the draw and cut (or sometimes draw and parry), an additonal cut, the blade cleaning and finally the re-sheathing. So not very long at all but there are at least 44 basic kata to master ( my sensei did make reference to 'hidden' kata which are only learned at a more senior level). All in different scenarios, for example attacks to the front, side or back, feints to induce attack, one is even meant for attacks in the dark. An interesting kata is the Nanahonme Junto which practices aiding someone in seppuku (ie beheading)!
Thats it for a brief introduction.
My objective here is just to bring to attention some of the points that I feel can benefit karate training ( again remember I have only trained Iaido a short time)
My observations I am going to break up into 2 parts for the moment ( if anything else comes to mind I will add later): technical and concepts.
Probably the point most harped on about by my sensei is the importance of the tanden. And as I found with most of my karate sensei, all the power and control comes from this point. It is the beginning of every technique and the outflow of energy. We would practice sometimes for the entire 2 hour session just going from a seated position ( seiza) to a kneeling position. Concentrating on driving forward with the hips. Oh and knee pads are essential for the beginner!!! My sensei would say that all movement begins with the tanden, first the breath and then the hips.
While on the subject of breathing, it was expected that only one breath be used to complete each kata, or at the least the first cut.
After, the tanden, foot movements are vital, the idea of drawing energy from the ground up. Your toes take a battering as they literally claw into the ground. Difference here with Shotokan ashiwaza is the very little use of the heel in propelling forward. Most of the time in Iaido ( while in zenkutsu dachi), the back foot has the heel in the air and the balance on the ball of the foot.
Again, we would repeat stepping over and over again to achieve a smooth, powerful yet controlled step.
In karate we say for the most part that when blocking or parrying we are in hanmi (half turned) while striking we are square on. While this is also true ( to a degree) in Iaido, for the most part, all techniques are done with square on hips ( again the driving of the tanden).
One of the really nice things about Iaido technique is the ability to tell a good cut from a bad one. As James states in another thread, the blade needs to 'sing' at the correct point. If anything is out of synch you can tell immediately, and believe me to get it right is no mean feat. Again, lots of hours spent just cut the air. In karate it might take an injury to tell you you are doing it wrong ( once broke my arm by incorrectly doing gedan barai!)
This was probably the most beneficial for me and it can be argued that these are true in most budo, but it was nice to see it from a different perspective. Terms like Zanshin, Ma ai, Ikken hitatsu, go no sen and sen no sen all have their Iaido equivalent but are sometimes used in different ways.
If we take zanshin and ma-ai for example. In karate, zanshin can be described as awareness of what is going on around you, while ma-ai is generally limited to the distancing between you and your opponent. In Iaido, the two work together in this way:
First up is zanshin ( before any conflict takes place) general awareness of surroundings, then comes the ma-ai ( this begins the moment you are aware of your opponents 'ill intent'). Ma-ai is not only the physical distance between opponent, but also, the rhythm (timing) and mind you share with your oponent, ie being able to 'read' your opponent.
Once you have dispatched the opponent, ma-ai is ended and you return to zanshin, this time 'a lingering heart' to ensure that no further attack will take place.
I was never taught in karate how the two could be related, they were always two seperate concepts.
Without going too much into go no sen/ sen no sen ( as these terms arent used in Iaio, as I can tell), I have used these to relate how Iaido operates. For many of the kata, you are striking first ( after sensing your opponents 'ill intent') thereby taking your opponent by surprise. This sense of 'ill intent' is what I feel should apply to my karate also. Many people have the "don't hit first" theory, if I feel threatened and there is no opportunity to talk or escape, then I am going to make sure I take my opponent down first, if that means hitting first, well then I better just make sure its a good one.
Finally and probably most importantly, is the ideal that there should only be need for one strike. While karate has the ippon or ikken hitatsu, Iaido has nukitsuke. The draw and cut. One technique to disarm, disable or dispatch an opponent. As I said most kata have an additional cut but this is only if needed. Its the all or nothing approach with nothing left behind. Once you have set your mind to attack, you go the whole hog and throw everything into it.
I think thats enough for now.... I hope have been able to convey a clear train of thought, but please comment and especially if anyone has trained in Iaido, it would be great to get your take on the subject.
For those interested a great source of information ( my Iaido bible) is the "Iaido Hongi" English translation, published by Airyudo, and written by Yamatsuta Shigeyoshi.