I am reasonable fit ( I run a 5.5km loop on average 5 times a week) but a long way from elite athlete territory. My resting heart rate is 46 with a 115/75 blood pressure. My doctor says it is genetic, God decided to set my heart rate at long range economy cruise
He also said that I should have a triple Espresso before my annual ECG because if the trace is below 50 it will trigger a bradycardia warning and cause a second level of review which is a PTIA.