Lumbar pain and numbness are caused by a variety of reasons, including lumbar disc herniation and lumbar muscle strain, as follows. 1. Lumbar intervertebral disc herniation: usually caused by heavy physical labor lumbar intervertebral disc herniation, the sciatic nerve is compressed and the pain radiates to the lower limbs, naturally affecting the muscles of the lower limbs, many people feel lumbar soreness and numbness of the legs when walking, due to the lower limbs are weak and achy. Even serious cases may appear lower limb limb paralysis, muscle loss of function. 2. lumbar muscle strain: lumbar muscle strain is due to long-term heavy load, physical labor or transient, acute lumbar sprain or poor posture, such as sitting for a long time and other reasons, are able to further lead to lumbar back pain and numbness in the legs. Numbness of the waist and legs may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.