There are many causes of numbness in the calf after walking for a long time, such as myofasciitis, lumbar spine lesion, sciatic nerve injury, etc.. Whether it is serious or not needs to be judged according to the cause and condition. 1. Myofasciitis: Walking too much, overexertion may lead to muscle damage in the calf, resulting in myofasciitis, the corresponding part of the calf may appear numbness, swelling. It is generally not serious, and most patients can relieve their symptoms through rest, physical therapy and massage. 2. Lumbar spine lesions: such as lumbar spinal stenosis, lumbar intervertebral disc herniation, etc., the patient walks for a long time after the symptoms of leg numbness, which is caused by the nerve root compression. Conservative treatment for milder conditions will have good results, and surgery can be performed if conservative treatment is not satisfactory. 3. Sciatic nerve injury: such as sciatica, there can be pain, numbness, soreness and sleepiness in the lower leg. This condition is mostly treated with medication or surgery. Mild sciatica can be relieved with rest and time. The symptoms of numbness in the calf after walking for a long time alone cannot accurately determine whether the condition is serious or not, it is recommended to clarify the cause of the disease under the guidance of a doctor and follow the doctor’s instructions for treatment.