Weakness and weakness of the legs and lack of energy can be caused by a variety of reasons, usually considered improper or excessive exercise, hypoglycemia, hypokalemia, aura of cerebrovascular disease, fever and other causes. It is necessary for the physician to take appropriate treatment measures and methods according to the different causes of the patient’s illness. 1. Improper exercise or excessive exercise: when the human body does not exercise for a long time or suddenly performs some more strenuous exercise without sufficient rest, there may be weakness in the legs and body. 2. Hypoglycemia: hypoglycemia can occur after excessive dieting or weight loss, which can be manifested as weakness of legs and body, dizziness, sweating, panic and other manifestations. 3. Low blood potassium: Low blood potassium can be caused by various reasons, such as vomiting and diarrhea caused by acute enteritis, etc. Low blood potassium can be manifested as weakness of legs and body. 4. Aura of cerebrovascular disease: For example, cerebral infarction and other diseases, due to ischemia and necrosis of brain tissues, abnormal neurological function may occur, which may be accompanied by weakness, dizziness, headache, numbness of limbs and other manifestations. 5. Fever: due to various reasons of fever, when the human body is feverish, especially when the fever is high, there may be weakness of the limbs. Need to go to the hospital, a clear diagnosis of the cause of the targeted treatment, they can not just use drugs.