So, why might it be a good idea to separate the martial from the art, at least for some of our practice? Consider one of the Feldenkrais principles I mentioned in previous posts: Concentration on the aim may cause excessive tension.
By placing these martial constraints on our motion, like ‘stay upright’ or ‘stay centered’ or ‘keep unbendable arms,’ we may be creating unnecessary tension in our motion and variance in our posture. By letting go of all the constraints and goals (i.e. of winning) and simply moving in contact with another person we may be able to learn what un-hindered motion feels like so that we have a reference point when we get back to practicing principled randori with martial goals. For another example of the type of motion I’m talking about (unconstrained by martial principles but still applicable to martial settings) check out this video of Tai chi silk reeling exercises. Silk reeling has the additional benefit that it can be done alone - unlike most aikido exercises/kata.