I am new to this site (just read your excellent book) so apologies if this has been asked before … but what is your perspective on various studies that seem to conclude that longevity is U shaped with regard to exercise and over a couple hours a week of moderate exercise is as unhealthy as being sedentary? (e.g., this article: http://healthland.time.com/2012/06/04/extreme-workouts-when-exercise-does-more-harm-than-good/?iid=hl-main-lede).
I was very disconcerted to read this, but have also read that other studies are contradictory (longevity increases with exercise) and that the extreme athletes tend to be extreme/high risk in other ways that can lead to premature death and hence distort the statistics. But anecdotally I have a friend marathoner who almost died recently from atrial fibrillation, which I then found out is 5 times more common for marathoners!
I am really looking forward to embarking on your more scientific approach to training for the long-duration sports I love but hadn’t considered this whole thing might not be healthy! Thanks.