Hi, I m a sports lover. I like playing soccer and running. I even participated in Half Marathon for a few occasions. The question here is, sometimes i do feel my heart beats fast in all of sudden and all i can do is to stop immediately whatever I m doing and wait till the heart beat turns normal. That same goes when i played other sports and it can happened even at the beginning stage and i know its not related to my stamina. The only problem is, it doesn t happened all the time. Would appreciate if you could help me understand my situation and what precaution or preventive method i can do in the future. Thank you.