It is normal for some people to have a fast heartbeat when they do something, but they should also be alert to hyperthyroidism, cardiomyopathy, coronary heart disease and other diseases. 1. Normal phenomenon: when the crowd in sports, mental tension or excitement, fatigue and other states, may appear fast heartbeat phenomenon. Therefore, it is normal for some people to have a fast heartbeat when they do something, so there is no need to worry too much. 2. Hyperthyroidism: the disease is related to Graves’ disease, iodine intake relative excess, etc. The patients mainly show that they are easily agitated, insomnia, fatigue, fear of heat, etc. Some patients may suffer from sympathetic nervous excitation. Some patients may have a fast heartbeat when they do something due to increased sympathetic excitability and accelerated metabolism. 3. Cardiomyopathy: The cause of most cardiomyopathies is still unclear, and may be related to genetics, viral infections, nutrient deficiencies and so on. Typical symptoms of patients include weakness, progressive dyspnea, shortness of breath after activity, palpitations (rapid heartbeat, often accompanied by panic), etc., which can also be manifested as fast heartbeat when doing something. 4. Coronary heart disease: coronary heart disease can cause some patients to do something fast heartbeat, but also easy to accompany chest pain, shortness of breath and other symptoms. Coronary heart disease is mainly due to plaque accumulation on the walls of coronary arteries, dyslipidemia, diabetes, obesity and other triggering factors. It is recommended that people who have a fast heartbeat when they do something should consult a doctor to check whether the disease is caused by the disease, so that early detection, early diagnosis and early treatment. Daily attention to rest, avoid strenuous exercise.