If you want to feel chest tightness and shortness of breath when the feeling of oxygen inhalation comes, it is best to monitor your heart rate and the exercise mode and intensity at that time.

If you didn't exercise at that time and your heart rate hasn't remained at a high level for 3 minutes after exercise (more than 85% of your maximum heart rate), to be on the safe side, I suggest you go to the rehabilitation department or cardiology department of the hospital to do exercise treadmill test, observe the ECG changes during exercise, and confirm whether you have heart disease, because some cardiovascular diseases can't be diagnosed by ordinary static ECG, and you must carry out exercise load test to make a diagnosis.

If you don't find this problem after the examination, it may be the cause of your physical condition, which can be improved by adjusting the exercise plan.