Left leg discomfort consider physiological causes, pathological causes, such as lumbar intervertebral disc herniation, lower extremity venous thrombosis, cerebrovascular disease, pear-shaped muscle syndrome, osteoarthritis and so on. 1. Physiological reasons: If you walk too much, it will cause muscle fatigue of the lower limbs and leg pain and discomfort. Localized discomfort may also occur if the lower limbs are compressed. 2. Lumbar intervertebral disc herniation: if the nucleus pulposus protrudes to the left side and compresses the nerves, it can cause pain and numbness in the left leg. 3. Lower extremity venous thrombosis: the left lower extremity thrombus blockage of blood vessels appearing lower extremity pain and discomfort, the left lower extremity vascular ultrasound can be clearly diagnosed. 4. Cerebrovascular disease: hemiplegia caused by cerebral infarction or cerebral hemorrhage may cause unfavorable movement of the left limb and impaired sensation. 5. Piriformis syndrome: the enlarged piriformis muscle compresses the sciatic nerve, resulting in pain in the left leg and limitation of walking. 6. Osteoarthritis: Joint hyperplasia and degeneration can cause limited joint movement and joint pain. If the discomfort in the left leg is not alleviated by resting, it is best to go to the hospital for examination to clarify the cause of the disease and further treatment.