The reasons for sitting for a long time leg numbness are as follows: First, most of them are caused by lumbar disc herniation, when the lumbar disc herniation, there can be protruding disc compression nerve, and leg numbness, especially after the sedentary lead to disc herniation aggravated, the symptoms of leg numbness. At this time, attention should be paid to the examination of the CT and MRI of the lumbar disc to diagnose and treat. Second, due to the pear-shaped muscle syndrome, pear-shaped muscle syndrome is the sciatic nerve at the pear-shaped muscle is compressed, and the symptoms of nerve damage, leg numbness. This is after the sedentary, can also have the pear muscle at the pressure and lead to nerve stimulation, the symptoms of leg numbness. It is important to pay attention to physical examination and check the electromyography of the nerves in the lower limbs for diagnosis and early treatment. In short, sit for a long time leg numbness should be diagnosed early, for the cause of treatment.