The libray at the Aviation Medical Centre (Henlow?)had some v.usefull stuff back in the mid-90s that seems relevant today. Looked into it in some detail after the RAF Doc told me that the poor design of the Wessex seat - and the hours spent in them with helmet/goggs/chest armour etc was responsible for giving me back problems. This was at a time when a mod would have been justified as the annual hours flown were silly. When he refused to put it in writing or in my medical notes I thought I'd better help myself.
The Ruskies have a lot of data on the subject aswell, all along the lines of what has been mentioned above.
It was amazing to feel the difference that resting your arm on top of the collective made - but this was banned because the collective could be knocked down during transit - go figure.
Suffice to say, there is a load of scary reading out there, if you dare.