Last Saturday I received a chair that is very very similar to this one (it's funny - I can't find the one I bought and this was just a few days ago).
I've been sitting on it ever since and it feels comfortable most of the time, but when I try to stand up or stretch, the back of my legs feels painful.
The part in red is where it hurts when I try to stretch.
I contacted customer support and this is what they said:
This is the first time we are hearing this but please be assured that I will do my best to assist and advise accordingly. While we are not certified doctors/health professionals, I can only advise that this might have occurred due to sitting habits such as leaning forward against their desks when seated, hence placing more pressure onto the underside of the thighs. Comfort is subjective and you may be facing this because you were transitioning from a softer chair to a firmer one. Please rest assured that as our chairs are designed to promote ergonomic health, and it will take some time to get used to.
I used to have a Herman Miller Celle chair and I've never had this problem, nor do I believe I had bad posture before. Could this really be a matter of getting used to it?? It's the third day in a row that I wake up feeling pain on my legs...