I read this article last week in Velo News and it really shook me up. I'm in my 50's, have been running or cycling regularly for 35 years and push myself several times a week. I will do 3-4 cyclocross races a year. I went in for my annual physical and my doctor, who is a marathon runner and exercise fanatic, noticed that my EKG showed--to anyone unfamiliar with my athletic background--that it appeared I was having a heart attack. He said it was because a portion of my heart was extremely strong. He sent me to a cardiologist for an echocardiogram to make sure everything was OK, which the cardiologist confirmed. He recommended that I shrink down my EKG and get it plastic coated and carry with me everywhere I go because if I am ever brought into an emergency room unconscious, the first thing that they will do after giving me an EKG is treat me for a heart attack. I haven't followed his advice yet, but with friends (and myself) getting into regular cycling accidents and the risk of developing AFib out on the road, maybe it would be a good idea. This is all scary stuff!