+1 on doping, but the context you provide is very interesting, thank you for the info.

Realistically, it's probably a "yes, and" situation. You don't get to that level without having a lot of natural talent, but... those years were what they were.

that's not why they had to get up. It's because they were hitting the EPO so hard, their hematocrits would be like over 60% (60% red blood cells/mL of blood) and thus when their heart rate/cardiac output would drop during sleep (to very low levels typically of highly trained athletes...not because of the EPO) the blood would be too viscous and start to clot

so the low heart rates caused a problem for those abusing EPO, but wasn't a result of using EPO

Thanks - and fair challenge.

Reviewing this, I realised I was guilty of an assumption: that as a low haematocrit can absolutely cause a high heart rate, so a high haematocrit might contribute to a low heart rate... but I can't find any support for this supposition. :)

Sadly, I can't edit my earlier post.

"Medlife Crisis" has an interesting video about this: https://www.youtube.com/watch?v=hT8GZlBBv5k (Cyclists' hearts: can you be so fit that you die?)

Also in Obree's book "Flying Scotsman" [0] where his attitude to "medical assistance" makes him "not a team player", and recounts how he'd hear certain teams running through the hotel at night to avoid the potential blot clots associated with EPO usage.

* https://www.amazon.co.uk/Flying-Scotsman-Graeme-Obree/dp/190...