Unexplained leg pain is leg pain that occurs when there is no external force, etc. It may be related to osteoporosis, lactic acid deposition, and lumbar spine lesions. 1. Osteoporosis: Commonly found in postmenopausal women and the elderly. The decrease of osteoblasts in the bones leads to the decrease of bone density and rapid loss of bone calcium, resulting in osteoporosis and symptoms such as fatigue and pain in the limbs. 2. Lactic acid deposition: may be walking too long, climbing mountains, etc., due to excessive leg muscle movement, a large amount of lactic acid deposition, after resting to show symptoms of leg pain. 3. Lumbar spine lesions: When lumbar spine lesions such as lumbar disc herniation and spinal stenosis occur, they may compress the nerve roots, and the leg innervated by the nerves will experience radiating pain. Unexplained leg pain can also be seen in other causes, it is recommended to consult a doctor in a timely manner, follow the doctor’s instructions for relevant examinations, with the help of the doctor to clarify the cause, and targeted treatment or treatment.