[jimhefferon]

I am a way-not-competitive runner. Jogger, really, since 1971. One marathon a year to get me out in the winter, best finish 4:30 (I am 58). No one ever said, "Uh oh, Jim is in this one, I'd better up my game."

But I had ablation at 43. So it is not clear to me that it is about pushing beyond boundaries.

[WalterBright]

I read that doing a marathon without proper and protracted training is very hard on the heart, so you may have been pushing too hard.

[jimhefferon]

I do the standard training, starting from 20m/w at the new year, and running on Memorial Day. (I follow Amby Burfoot's excellent plan.)

Certainly my story is anecdotal. But I guess I'm just saying that while bodies are amazing, sometimes they are amazingly frail.