Whether or not a heart rate of 170 beats per minute during exercise is dangerous depends on the actual situation, and is normal for professional athletes or those with a more tolerant body. However, if the body cannot tolerate it, there is a risk of cerebrovascular insufficiency, which is dangerous. The heart rate during exercise also needs to be judged in conjunction with the actual age. The maximum heart rate is the highest level of heart rate that can be achieved when oxygen consumption and heart rate cannot continue to increase at maximum load intensity, that is, the maximum heart rate of exercise = 220 – age. However, it is not recommended to reach the maximum exercise heart rate when exercising, only 60%-80% of the maximum heart rate can be achieved. So if you are 20 years old, the best exercise heart rate that is 120-160 beats/min, but this refers to healthy young people, if the elderly with chronic diseases, the best exercise heart rate to be lower. Therefore, the heart rate of 170 beats / min when running is a little fast, but need to pay attention to the presence of obvious symptoms of discomfort. Exercise must be combined with their own situation to determine the best daily exercise 30-60 minutes. If the exercise time is too long or too strenuous, the body is easy to fatigue, thus increasing the probability of injury.