Aspartate aminotransferase 300 U/L may be caused by strenuous exercise. Aspartate aminotransferase usually does not exceed 40 U/L, it is mainly found in the liver and myocardium, this is one of the tests to check whether the liver function is damaged or not, clinically, there are physiological reasons and pathological reasons for the elevation of the enzyme. Physiologic causes include strenuous exercise, pregnancy, and irregular rest and diet. Pathologic causes such as acute and chronic soft tissue injuries, frequent alcohol consumption, smoking, viral hepatitis, alcoholic liver disease, cirrhosis, myocarditis, myocardial infarction and other diseases can also lead to elevated results. Aspartate aminotransferase test results are abnormal, it is recommended to go to a regular hospital combined with other related examinations to determine the cause of the disease, and then targeted treatment under the guidance of the doctor, so as not to delay the condition and miss the best treatment period.