Whether or not a heart rate of 170 beats per minute is dangerous when running is determined by the person’s athletic state and physical condition. For professional athletes, a heart rate of 170 beats per minute can be tolerated. However, for sudden high-intensity exercise, the sudden increase in heart rate to 170 beats/min will cause physical discomfort and can be life-threatening in serious cases. The normal adult heart rate limit is 220-age, the usual exercise heart rate to maintain the highest heart rate of 60%-80%. When the heart rate is at 170 times / min, for people who exercise less, chest tightness and dizziness during exercise, it is necessary to reduce the amount of exercise and reduce the intensity of exercise. For people who run only for weight loss and fitness, the effective range is to maintain the heart rate between 120-150 times / min, when the oxygen intake is larger, belongs to the low and medium intensity training, is a better aerobic metabolism, runners will also feel very relaxed, the body rarely discomfort.