The heart, which supplies blood to the entire body, seems strong but is actually fragile. American cardiologists, based on years of clinical experience and a number of international studies, have found that the heart is most vulnerable during three periods of time. 1. After overeating In order to digest food, a large amount of blood to the gastrointestinal transfer, the supply of blood to the heart is relatively reduced, thus aggravating myocardial ischemia, increasing the burden on the heart. If you eat too greasy and consume too much fat, it may also lead to an increase in blood viscosity, promoting thrombosis and triggering myocardial infarction. Suggestion: It is best to eat seven or eight minutes of satiety at each meal, and control fatty meats, animal offal and other high triglyceride, high cholesterol foods. If you often have chest tightness, chest pain, rapid heartbeat and other discomforts after a full meal, you need to go to the hospital in time to rule out heart problems. 2. When straining to defecate When straining to defecate, you need to hold your breath, the abdominal wall muscles and the diaphragm will strongly contract, so that the abdominal pressure rises, thus causing a sudden rise in blood pressure, myocardial oxygen consumption increases, inducing angina pectoris, myocardial infarction, and serious cardiac arrhythmia, which may cause sudden death in severe cases. Suggestions: Even if the stool is dry and difficult to discharge, do not be too hard, if necessary, can be used to cope with the auxiliary methods such as Kaiser Permanente. In order to ensure smooth stools, it is usually best to eat more dietary fiber-rich fresh fruits and vegetables and coarse grains, but also drink more water, moderate exercise. 3. Strenuous exercise Appropriate exercise contributes to physical and mental health, but strenuous exercise will force the heart horsepower full open, each contraction several times more blood to the whole body, so it is easy to cause a sudden rise in blood pressure, heart rate is too fast, myocardial hypoxia, and even lead to a heart attack. Suggestion: It is best to carry out aerobic exercise such as brisk walking, jogging and other milder aerobic exercise, and it is best for the elderly and those with bad hearts not to participate in competitive sports. Exercise heart rate should not exceed the target heart rate (40 years of age with 180 minus age, 40 years of age with 170 minus age), and exercise time should not be too long, about half an hour is appropriate. If chest tightness, shortness of breath and other discomforts occur during exercise, you should sit down and rest immediately.