Guess what, I found out the better your cardiovascular system is trained the slower your heart actually beats. At all times.
If you are an athlete, at rest your heart will probably successfully pump blood with only 40–55 beats per minute, but if you don’t work out it will need twice as many. Thus it’s likely to give out much earlier. There is a table.
And note that despite all the cheating Lance Armstrong’s heart still has (how do I put this?) more than impressive, no, almost unbelievable 32 pbm.
Fascinating and doubtlessly exciting, although perfectly logical. How could I not make this connection myself.