Re: training without training?
It's possible, IMHO. I'm new to aikido, old to music. Music is physical, too, but it is possible to get better as a musician even while taking time (a few months) away from the instrument. It's a matter of imagining the music and the fingering of the instrument oftentimes during the day. You have to be an expert already, though, in order to make improvement through imagination and time off. I've made this kind of improvement and have heard from other musicians that they have, as well. I guess its a matter of refining pathways in the brain.
If you have to be away from any practice place and you are already an accomplished aikidoka, I bet you can profit by using your imagination to recreate your moves during that time.