Lumbar pain and weakness can be caused by a variety of reasons, including physiological reasons such as lumbar muscle fatigue, pathologic reasons such as lumbar disc herniation, osteoporosis and so on. 1. Physiological reasons: Mostly due to long time bending, long-term bad sitting posture and other reasons caused by lumbar muscle fatigue, manifested in lumbar pain and weakness and other symptoms. Generally, the symptoms can be relieved after resting for a period of time. 2. Lumbar disc herniation: the most common is lumbar disc herniation, the protruding nucleus pulposus or intervertebral disc compression of the peripheral nerves, resulting in lumbar pain and weakness, accompanied by numbness of the legs, sciatica and other symptoms. 3. Osteoporosis: mostly seen in the elderly, there is often calcium malabsorption, easy to cause osteoporosis, manifested as lumbar, lower limb pain, can be accompanied by soreness and weakness. Soreness and weakness of the waist and knees can also be seen in other causes, such as lumbar myofasciitis, etc. It is recommended to exclude the physiological causes, and then go to the hospital in a timely manner, so as to clarify the cause of the disease and timely treatment.