Well I want my cake and eat it really. The idea is to have both short and long term feedback. i.e. it tells you if you're doing the motion incorrectly as you're doing it, as well as recording the motions you actually do so that you can see your performance over time and tell where you are on the recovery journey.
I will go with a PC setup for the moment, that will be enough of a challenge to be getting on with. I thought perhaps that by storing numbers on an SD card, the Arduino could dip into it and get the info it needed where necessary