Fasting exercise is generally recommended not to exceed 30 minutes, because if the exercise time is too long, it may have an impact on the heart, and may also occur hypoglycemia, hypertension and other conditions. 1. Impact on the heart: prolonged fasting exercise will break down energy from fat, resulting in increasing free fatty acids in the blood, which may have an impact on the heart, arrhythmia and other related symptoms. 2. Hypoglycemia: if prolonged fasting exercise, also prone to hypoglycemia, palpitations, dizziness, cold sweat, hunger and other symptoms, especially diabetic patients prolonged fasting exercise or strenuous exercise, it is easy to hypoglycemic reaction. 3. High blood pressure: If a long time fasting exercise, may cause sympathetic nerve excitation in the body, will make the heart rate and blood pressure rise, especially with high blood pressure of the population, to avoid a long time fasting exercise or strenuous exercise. It can be seen, fasting exercise is best not more than half an hour, it is recommended that after eating about 1 ~ 2 hours to exercise, to avoid hypoglycemia, cardiovascular and cerebrovascular accidents and other situations.