Soreness in the middle of the lumbar fossa may be caused by physiological factors, chronic strain, lumbar disc herniation and other factors. 1. Physiological factors: such as prolonged exercise or prolonged labor, a large accumulation of local lactic acid may lead to lumbar pain in the middle of the lumbar fossa, the symptoms are not obvious, and after reasonable rest, it can improve on its own. 2. Chronic strain injury: it may be related to prolonged exposure to cold or prolonged heavy physical labor, which may lead to soft tissue damage in the middle of the lumbar fossa and aseptic inflammation, and the symptoms of soreness in the middle of the lumbar fossa may occur frequently, and there may be pain when pressed. 3. Lumbar intervertebral disc herniation: it may be related to lumbar degeneration, acute injury and other factors, when the lumbar intervertebral disc herniation, it may cause lumbar fossa middle pain symptoms, may also be accompanied by lower limb numbness, lower limb pain and other symptoms. Soreness in the middle of the lumbar fossa is more obvious, excluding physiological factors, it is recommended to consult a doctor in time for examination and treatment, to avoid causing other complications.