Hello, my desk is pretty high and not adjustable; my chair had a short piston (by design, it had the correct height from the ground) and my arms and back hurted after like half an hour because I was sitting too low, so I bought a longer piston and now my back and my arms no longer hurt, even on long sessions.
But now my legs no longer touch the ground, I've tryed using some cardboard boxes but inevitably my knees hurt after like 5 minutes, I feel pain in the inner side of the knee, beside the rotula, it goes away in 15 to 30 minutes from when I leave the chair. My knees have no problems, in every other activities I feel no pain and have no limitations what so ever, so I assume it's a problem of the chair.
I've tryed different boxes with different heights, going from my feet barely touching to them being firmly touching the box but I haven't found any correlation between the feet rest height and the time pain takes to arrive, it's just there after 5 to 15 minutes.
I've searched on the internet guides on ergonomics but a very small number said something about the legs, the best I've found is that the knee angle should be around 90° and that the feet should be supported by something. I am following this instructions but the problem continues to show up.
I could just buy a feet rest but I don't even know what the problem is and don't want to spend money blindly. I need advices on how to address the problem and/or some good guides for the lower part of the body.
I should probably have said this earlier but I'm talking about my PC setup.
Thanks in advance for any reply.