Originally Posted by Howzit

Exactly.
Big Migs resting heart rate in some circles was reported to be something like 28 when he slept, you can easily slip into cardiac arrest. (Im not saying anything about Big Mig or a connection to EPO, just saying resting heart rates can become even lower with EPO for an elite athlete whos fitness already lowers their heart rate through training) Some riders are also known to have slept with Heart Rate monitors to wake them up when they dipped too low.

This is exactly why I feel like the 50% UCI rule was great. It was a safety net and playing field leveler. Safety from cardiac arrest, and making everyone have the same cap. Since this rule was enforced, people like Riis couldnt run their 60%s anymore.