https://openheart.bmj.com/content/9/2/e002154
> Conclusion: Although older male endurance athletes experienced an increased risk of AF, the long-term risk of stroke was substantially reduced compared with non-athletes.
Higher probability with zero exercise, lowest probability at moderate exercise, but an increase in probability as you enter the extreme territory. In my case, 1000+ hours/year for 8 years led to this outcome
Eliud Kipchoge, WR in marathon, seems to only be doing one hard faster than race pace workout each week. Call that the HIT. The others are slow or race pace. What actually stands out most to me is the specificity of running close to a race pace marathon every week. https://www.sweatelite.co/eliud-kipchoge-a-typical-week-of-t...
Then on the other end of the spectrum, the Ingebrigsten family of runners seems to put an emphasis on quality. But even though they do more faster running they keep a lid on the intensity to avoid training to exhaustion. It actually reminds me more of the "Grease the Groove" concept where the faster running may be more for neurological reasons. https://www.outsideonline.com/health/running/culture-running...
Anyway, neither of these two training models seem to have much in common with HIT. The bulk of the workouts are easy intensity and they are both seemingly ware of the dangers of high intensity. That's where injuries come from and so there can't be too much of it.
Suspect that this is also for neurological reasons