There are many reasons for soreness and swelling of the lower back and legs, such as strenuous exercise, lumbar disc herniation, and third lumbar transverse herniation syndrome. 1. Strenuous exercise: after intense physical activity, it can lead to the production of a large amount of lactic acid and metabolic products in the body, due to lactic acid can not be excreted from the body in a timely manner, it will lead to the phenomenon of soreness and swelling of the waist and legs. 2. Herniated lumbar intervertebral disc: Herniated lumbar intervertebral disc causes the nerve root to be compressed due to the prolapse of the nucleus pulposus, which leads to the phenomenon of lumbar and leg soreness and distension, and is accompanied by the phenomena of limited lumbar activities and leg numbness. 3. Transverse third lumbar vertebra syndrome: Transverse third lumbar vertebra syndrome can also lead to soreness and swelling of the lower back and legs, due to the inflammation of the transverse third lumbar vertebra, which affects the nerve roots and lumbar vertebrae, resulting in soreness and swelling and pain. There are many reasons that lead to soreness and swelling of the lower back and legs, go to the hospital in time to improve the examination after the symptoms appear, follow the doctor’s instructions to give standardized treatment, do not ignore the symptoms, so as not to delay the treatment of the condition.