The maximum normal heart rate for running is 220 minus your age. Sixty to eighty-five percent of the maximum heart rate is a more appropriate heart rate for exercise. Heart rate is the number of heartbeats per minute. A normal heart rate in a quiet state is 60 to 100 beats per minute. When running, the heart rate may accelerate to different degrees depending on the speed or time of running due to sympathetic excitation, increased secretion of adrenaline, dopamine and other vasoactive substances. If the heart rate is maintained at 220 minus 60% to 85% of age during running, it will not cause symptoms of insufficient blood supply to the heart, such as chest tightness, shortness of breath, and dyspnea. If the heart rate is significantly lower or higher when running, further examination of electrocardiogram, cardiac ultrasound and other items are needed to find the cause, as well as controlling the amount of exercise and avoiding overexertion and emotional excitement.