Sitting back pain, pain with the prolongation of time aggravation, lying down is not pain may be related to the lumbar back myofasciitis, lumbar muscle strain, lumbar spine instability. 1. Lumbar back musculoskeletal fasciitis: mostly occurs in cold, wet areas of field workers, etc., the lumbar back muscle vasoconstriction, edema, ischemia, and ultimately the formation of fibrositis. It can also appear as a symptom of no pain after lying down, and pain after sitting after fatigue. 2. Lumbar muscle strain: often due to cold stimulation or sedentary, stooping work, resulting in chronic injury to the lumbar muscles, at this time lying down without pain, after a day of exertion, lumbar back pain will be aggravated. 3. Lumbar spine instability: lumbar spine instability is common in the elderly lumbar spine with age-related degenerative changes, often manifested in the lumbar spine segments of the range of motion or joint displacement abnormalities, which can easily cause low back pain. The pain is often relieved after lying down, and often dare not sit or bend over for a long time. If you have back pain after sitting and the pain increases with time, but not when you lie down, it is recommended that you consult a doctor for further examination as prescribed by the doctor, so that the cause of the pain can be clarified with the help of the doctor, and targeted treatment can be carried out.