RS Mishima (1) et al reviewed fifteen studies with a total of 1,464,539 individuals from databases of prospective cohort studies to determine the risk of atrial fibrillation (AF) at various exercise levels compared with those individuals who did not meet guideline recommended activity levels.
The current exercise recommendation are at a minimum 450-500 met minutes per week.However, both the US panel and more recently WHO have also said that higher levels, i.e. 2 or 3 times that amount will likely results in greater health benefits. The health benefits are apparent in large epidemiology studies which have demonstrated a curvilinear relationship between exercise volume and reduction in cardiovascular and all cause mortality.
500 met-minutes per week is equivalent to 2 1/2 hours of moderate (less than 7 METs) exercise or 1 1/4 hours of vigorous exercise.
While studies of long time athletes have generally shown longer longevity there have also been reports of an apparent increased risk of atrial fibrillation (AF) in endurance athletes particularly those who exercise at levels many times the minimal recommended level .
Mishima found that at exercise levels up to the 2000 met minutes per week level ( four times the minimal recommended level )there was a decreased risk of AF but "past that point the benefit is less clear".At levels less than 2000 there was a 6 -11% lower risk of AF. At least in this study the upward arm of the U was not found.
(1) Mishima,RS et al Self reported physical activity and atrial fibrillation risk: A systematic Review and Meta-analysis, Heart Rhythm 2020 Dec. 18