Just busting your balls here, but talk about incongruity. ;P
If you really enjoy it, more power to you. I would caution you, since this is a health thread and not just fitness, that extreme endurance running can have adverse effects for your long term health. Give it some thought is all if you plan on making the enduro runs a regular occurrence as opposed to a one time thing.
No one runs marathons or ultras for health, that's for sure. And it certainly can compromise your long term health, if you attack events that you've not trained adequately for. But there is no evidence whatsoever that it does in 99.9% of cases, and certainly not in fit people without preexisting conditions. Tests of athletes in the days right after an ultra yield an expected amount of damage, but it goes away in a matter of weeks. In cases where long term heart scarring occurs, the athlete in question pushed themselves beyond their fitness, and got injured. It's like any other sport, in that regard. You invite an element of risk, but you can mitigate it, through proper training and an intelligent "game plan". Suffice it to say, my heart is in perfect condition, and my hormone levels are all in optimal ranges, even after having run six marathons/ultras in the last year.
Hopefully I don't sound too defensive here. I'm not arguing your point per se. Certainly there are bucket listers who get themselves hurt, or people who exacerbate heart conditions that had not been previously detected. For that reason, I encourage everyone I run with to emphasize a steady progression, and never race above their training. I try and do everything I can to heed that advice myself.
But you are fundamentally right, that if health is your only goal, I'd probably advise maxing out at 30 miles a week or so, and never racing marathons or longer.
