There are many reasons why you can’t breathe after running for a while, mostly considered to be caused by long-term lack of exercise, cardiopulmonary diseases leading to cardiac or pulmonary insufficiency. 1. Lack of exercise: long-term lack of exercise in the population may be reduced exercise tolerance, increased oxygen consumption after strenuous exercise, the body can not compensate, exercise chest tightness and shortness of breath, dyspnea and other manifestations. 2. Cardiac insufficiency: such as myocardial ischemia, cardiomyopathy, cardiac valvular disease and other diseases on the basis of the heart, resulting in the function of the heart does not reach the normal level. After running, the heart’s pumping ability is insufficient to maintain the body’s oxygen demand after strenuous exercise, and the performance of breathlessness occurs. 3. Lung insufficiency: such as bronchitis, asthma, pneumonia, emphysema and other respiratory system pathologies, affecting lung ventilation or gas exchange function. After strenuous exercise, the inhaled oxygen cannot meet the body’s needs, and the performance of breathlessness occurs. In short, if the performance of breathlessness after running occurs, you should go to the regular hospital in time, under the guidance of the doctor’s treatment.