Definitely some amount of it is natural, I'm even less competitive with running than you, but seeing my resting heart rate go down as you ramp up distances is a satisfying thing when you realize the hard work is paying off in a "tangible" way :)
I did a little more googling after the above comment, and it seems like another factor that (in theory) plays into the issue for the anecdote is that their blood can get thicker from doping. So it's a recipe of very low heart rate + extra viscous blood to pump that = danger.
Regardless, it's some pretty interesting/freaky stuff!
I did a little more googling after the above comment, and it seems like another factor that (in theory) plays into the issue for the anecdote is that their blood can get thicker from doping. So it's a recipe of very low heart rate + extra viscous blood to pump that = danger.
Regardless, it's some pretty interesting/freaky stuff!