Originally Posted by
bmcer
Afterward, I had occasion to ask my cardiac surgeon what role, if any, my 100+ mile/week (about 33% of which was done at a tempo or higher intensity level) played any role is what happened to me. His response? "Damned straight it had something to do with it. Had you not been that well conditioned, you would have had a less than 3% chance of surviving the event you sustained.
I don't think anyone's debating that exercise is good for your heart. And 100 miles a week of recreational riding with some intervals thrown in isn't the "excessive exercise" that's at issue.
I think there is a real question of whether 200 miles a week, 6 days a week, doing intervals at 100% effort, and multiple days of racing still makes health sense in your 50's particularly if it's on top of a lifetime of doing that.
I think it's very likely that 100 miles or so a week of moderate recreational club rides, balanced with some other recreational activities thrown in gives you all the health benefit you can get, and that pushing to the very limit of what your capable of, which many Masters racers, and triathletes do, adds no health benefit, and likely increases your risk of sudden cardiac death, and problems like a fib.
So I think if you continue to race into your 50's, you should be honest with yourself, and realize the rationale for doing so is not better health.
And as one off anecdote, I have a 59 year old friend, lifetime bike racer, maybe 5% body fat, who just underwent ablation for A Fib.
Sample of one, but consistent with Zinn's and others experience.