[cullenking]

Yup! I watched a 50 year old fit guy drop dead in the first 10 miles of a 100 mile ride. He was gone before he even hit the ground. It's pretty common in hard endurance sports to hear about heart failure, though I think the benefits outweigh the risks in the long term. This is assuming you are training a normal/sane amount, getting plenty of rest, listening to your body etc etc. Work hard play hard doesn't last forever.