In general, lumbar sprain in January after lying pain but sitting on the pain considered for the lumbar dorsal myofasciitis, lumbar disc herniation, lumbar spine instability and slip and other diseases. 1. Lumbar dorsal myofasciitis: acute aseptic inflammation caused by lumbar sprain can lead to lumbar dorsal myofascial edema, oozing and fibrous degeneration when the lumbar dorsal muscles are involved, which can cause lumbar pain and tenderness, and the contraction of lumbar dorsal muscles caused by sitting can lead to the emergence of pain or aggravation of pain. 2. Lumbar disc herniation: lumbar sprain can lead to rupture of lumbar intervertebral disc fibrous ring, so that the nucleus pulposus protrudes or prolapses, which stimulates or presses the nerve root, causing lumbar pain and lower limb numbness, radiating pain. The symptoms of nerve compression can be aggravated when sitting. 3. Lumbar spine instability and slippage: lumbar sprain can lead to lumbar spine ringing two vertebral body activity abnormality or relative slippage, can cause lumbar back pain and lower limb radiating pain and other symptoms. Lumbar sprain in January after lying pain but sitting on the pain may also be caused by soft tissue contusion, patients are advised to recommend timely medical treatment in order to clarify the diagnosis, targeted treatment.