Weakness and stiffness of the legs may be related to leg muscle strain, neurological diseases, lumbar spine diseases and so on. 1. Leg muscle strain: due to strenuous exercise, standing or walking for a long time, the joints and muscles of the legs are repeatedly stretched, resulting in local edema, congestion, lactic acid accumulation and other phenomena, and in severe cases, aseptic inflammation can be formed, which is often manifested as weakness and stiffness of the legs. The above symptoms can be aggravated when the legs are cold. 2. Neurological diseases: such as cerebral hemorrhage, cerebral infarction, etc., often due to nerve damage, resulting in increased muscle tone, which leads to symptoms of weakness and stiffness of the legs. It can also be manifested as distorted eyes and mouth, confusion, and limb movement disorder. 3. Lumbar spine diseases: some lumbar spine diseases, such as lumbar disc herniation, lumbar spinal stenosis, etc., will cause compression of spinal nerves, so that the legs appear uncomfortable symptoms, which can be manifested as weakness and stiffness of the legs. If the symptoms of weakness and stiffness are not relieved, or accompanied by other symptoms, you should go to the hospital in time, and give targeted treatment after clarifying the cause.