question: Hi, whenever I sit on HARD chair for more than 10 minutes, my left calf becomes numb and tight. When this happens, I will walk around and it becomes better. If I have sat down on hard chair for too long and the numbness is bad, I will have to lie flat on my back on a SOFT bed for hours, then the numbness goes away. But this numbness and tightness on calf doesn t happen if I sit on soft sofa or lie on soft bed even for hours. Other parts of the leg and my back are ok. No pain. May I know what s wrong?