Extreme distance running is associated with atrial fibrillation and arrhythmogenic right ventricular dysplasia (ARVD) due to fatty tissue infiltration in the right ventricle.

“i saw multiple distance runners come in with atrial fibrillation arrhythmias one marathon isn't going to do it to most any humans right right but like distance runners i was a distance from a long time it's a [ __ ] addiction you know this is this right and and i saw a lot of marathoners come in with arvd which is a rhythmogenic right ventricular dysplasia so you get you get infiltration of fatty tissue into the right ventricle of the heart with like extremely long distance running”