Pilots are like tires at EK, they wear you out and then replace you.
Regarding the issue of seat design, I believe a bigger factor is actually the amount of time we spend sitting in the seat. We could have the best seats ever designed but we would still suffer from back pain due to the duration of the flights.
The reality of the spine is that it is also a hydraulic shock absorber The longer we are upright or sitting the more compressed that shock absorber becomes, hence the reason that the medical community suggests eight hours of sleep a night. The eight hours of sleep allows the spine to decompress after the effects of gravity throughout the day.
Unfortunately it is to the point where I normally have to start my day with two advills before I can get up, this is because of the back pain I have only started to suffer since working for emirates and the associated longer schedule.
90+ hours per month, every month just hurts!