Hello there. I can understand your concern. The heart rate is under the control of a complex pathway which involves the brain and many chemical neurotransmitters along with hormones. When you are stressed out/anxious/in fear there is a sudden rise in the adrenaline which is called the adrenaline rush which causes the heart rate to increase. During running/exercise/jogging etc. There is a demand for oxygen created by the tissues of the body which causes the heart rate to increase. So its pretty normal, everyone experiences this. What different are you experiencing. Nothing to worry about here. Regards, Dr. Anil kumar jain.