Left posterior lumbar pain, if the pain suddenly attacks during exercise, is considered to be caused by sprain of the left lumbar muscle, which may appear to be restricted in turning activities, and is considered to be pain caused by chronic strain of the lumbar muscle, which is mostly seen in patients with long-term bending work or heavy physical labor, and is easily induced by overexertion or local cold. Left posterior lumbar pain is considered to be pain caused by changes in the anatomical structure of the lumbar spine and compression of nerve roots, which may be accompanied by radiating pain and numbness in the lower limbs, such as lumbar disc herniation, lumbar spinal stenosis and lumbar spondylolisthesis. Consider pain caused by lesions of the posterior peritoneal organs, such as inflammation of the left kidney and stones, and consider pain caused by inflammation of the left pelvis or adnexa.