When you feel out of breath when you run, most of them are caused by poor heart and lung function. When running strenuous exercise will increase the burden on the heart and lungs, which will cause the heart rate to speed up and breathing to speed up, and most of the blood in the whole body will supply the limbs, which will cause poor blood supply to the heart and lungs, which will also have a certain impact on the function of the heart and lungs. Usually do not pay attention to exercise, but also easy to cause this phenomenon. To avoid strenuous running exercise, you can first exercise by brisk walking, you can also do the heart and lung function check, if there is a problem is the need for timely medication to regulate. There is hypertension, high blood pressure is also a certain impact, usually need to light diet, low salt and low fat diet, need to control blood pressure and blood lipids within the normal range.