The normal heart rate is 60- 100 beats/min. If it is lower than 60 beats per minute, it is bradycardia, and if it is higher than 100 beats per minute, it is tachycardia. Tachycardia is caused by physiological reactions, such as exercise, drinking, emotional excitement, etc., but it generally does not exceed 150 beats/min, and it has pathological reactions, and the heartbeat can reach 180-250 beats/min, which is seriously life-threatening; Bradycardia also has a physiological reaction. For example, athletes' heart rate is slower than normal, about 50-60 beats per minute, but they are healthy and have pathological reactions. When the heartbeat is less than 40 beats/minute, it will be life-threatening.