Weak legs and a little leg pain may be caused by spinal stenosis, intervertebral disc herniation, pyriformis syndrome and other reasons, the specific causes need to go to the hospital to determine the examination. 1. Spinal stenosis: Spinal stenosis is mainly caused by congenital developmental abnormalities, trauma, infection and other reasons, if the patient suffers from cervical spinal stenosis, the pain is mainly manifested in the patient’s scapula area, neck, back, shoulders, etc., and the pain can be radiated to the lower limbs, so that the patient’s lower limbs appear numbness, leg weakness and other symptoms, the condition is more serious, but also urinary and fecal dysfunction. 2. Lumbar disc herniation: Lumbar disc herniation is mostly caused by long-term work, heavy physical labor, heredity and other factors, lumbar disc herniation stimulates the body’s tactile and sensory fibers, which will make the lower limbs numbness, and when the nerve root is damaged, the patient will experience weakness in the lower limbs, which will make the patient’s legs soft and lack of energy. 3. Piriformis syndrome: Piriformis syndrome may be caused by hip sprain, heavy walking, cold and other reasons, the patient’s pain is mainly in the buttocks, the pain will radiate along the sciatic nerve to the calf, the back of the thigh or foot, when the pain is severe, it will cause the patient to have symptoms of leg weakness and lack of energy. If there is weakness and pain in the legs, the patient should go to the hospital in time and be treated under the guidance of the doctor after diagnosis.