Weakness and shortness of breath. Lack of energy. Leg weakness is usually caused by several conditions: First, the most common cause is the initial stage of the cold, in the bacterial cold when you feel weak, legs and feet, weakness around the body, at this time, you should go to the hospital for blood tests, select the drug symptomatic treatment. When the blood supply and oxygen supply to the heart arteries are insufficient, people will feel weak, accompanied by obvious chest tightness, shortness of breath, exertion, and discomfort in the precordial area. If too much work will feel tired, these symptoms are the result of cardiovascular insufficiency. When the cerebral artery, especially the vertebrobasilar artery, is not supplied with enough blood, the person feels weak, short of breath, and weak. Fourth, skeletal muscle insufficiency, such as rhabdomyolysis, will also feel weakness and leg weakness. Regardless of the cause of weakness, shortness of breath, lack of energy and weakness of legs, it is recommended to go to the hospital for systematic examination to avoid affecting or delaying the condition.