To answer your question about suburi, it may be useful to get a clear understanding of what can be learned form suburi and what to look for.
I can only talk about so called "Iwama ryu" ( I don't like the name itself but it has become common place so let's use it ... The net is only useful to catch the fish, etc).
Saito sensei's method includes 7 ken suburi, each of them having a precise role. Maybe we could begin with the first one as it is the foundation of pretty much everything else.
Aikiken is not a sword school per se although after some practice you wouldn't feel lost in a ken centered practice. It is all linked to aikido principles, it is a method to teach the body how to move, and refine its perceptions.
I doubt this can be done on a forum but let's try to summarize. (If you speak french - but the article will be soon translated - you can read this
as it provides with a clear understanding of what to seek in the 1st suburi).
Let's try to summarize:
- ichi no suburi is a way to discover irimi tenkan principle (too long to explain here but let's say that when you step forward -irimi- , your spine rotates - tenkan- the leg spiraling backward being only a consequence of the rotation and not its engine...)
- it teaches the correct way to rise the sword (not with the shoulder but with the entire body)
- it leads to a more rational use of the body in all aikido techniques
- it creates kokyu power (that ellusive internal power too often described as mysterious... it's a bit like drawing, all is known, the technique is known, go to work ;-)
- hanmi right, front foot comes in front of the inside of the left foot
- the movement drags the whole right side of the body back, allowing your right hand/arm to pull the sword back and up with a minimum effort of the deltoids muscles
- relatively the left side pushes the sword, creating a leverage with the right side in order to minimize the effort upward and collaborate with the right side.
- ultimately after a few thousands (depending on your commitment) you'll feel that both hands end up pushing
, creating and developing the kokyu power inherent to Aikido (a work refined by the 2nd and even more by the 3rd suburi - a pure kokyu breeder...). In that case the link with kokyu ho becomes obvious, these are two closely related movements, similar in essence, leading you to the discovery of the principle behind the forms.
Through the rotation on the spine axis, the whole body is unified to set the ken in motion with a minimum effort of the arms. The consequence is a better use of the body in all tai jutsu techniques (example: fifth suburi - shiho nage but it starts with ikkyo really). As such, weapon training - starting with suburi - helps the practitioner right form the start
and not after years of endless air cutting although commited training is required to get the best of it, like everything else.
It is worth trying different speeds and amplitudes of movements with a quite heavy bokken (900 g is fairly enough, the number of painfree suburi being an indicator of the correctness of the exercice) in order to identify the issues revealed by cramps even if these are a bit inevitable, let's be sensible here, no physical practice is completely pain free but it is a good excuse to get a nice massage.
I really discourage the use of any heavier weapon (furibo 3,5 kgs for instance) to avoid back injuries. These tools require a deep uunderstanding of the movement, otherwise you may ruin your back very easily. Of course after a year of suburi, the furibo will deepen the feelings and lead to a stricter self correction.
Hope this can help.