The pain in the lower back after sitting for a long time belongs to the lumbar muscle strain, mainly due to two reasons: 1, due to sitting for too long, the muscles of the lower back continue to be stretched and tense, for a long time will lead to excessive fatigue of muscle tissue to form a strain, producing more lactic acid, inflammation and other metabolic products, stimulating the peripheral nerves of the lower back will appear obvious pain symptoms, especially when sitting on a relatively short bench. 2, because the waist cold, because in the sitting position when the waist usually clothing cover is not enough, will lead to the skin parts of the cold situation, a long time muscle tissue appeared cold, will lead to muscle tension, and blood circulation will appear obvious decline, the local can not get more energy and electrolyte support, the local nutritional status is relatively poor, if the venous return and then appear to have a very low level of pain. If the venous return is slowed down again, the metabolic products produced locally will not be easily metabolized and will accumulate and increase, which will more easily induce the symptoms of lumbar pain.