Heart HealthHigh Fitness in Youth Protects the Heart Despite Slight Atrial Fibrillation Risk
A longstanding concern among athletes and coaches is that high fitness levels may raise the risk of atrial fibrillation, a potentially serious heart rhythm disorder. A landmark Swedish study of over one million men, tracked from military conscription in their late teens through their mid-fifties, finds that while high adolescent fitness is linked to a modestly elevated atrial fibrillation risk, this is substantially outweighed by large reductions in strokes, heart attacks, and other cardiovascular diseases. Crucially, when comparing brothers — controlling for shared genetics and upbringing — even the early-adulthood AF disadvantage disappeared, leaving only net cardiovascular benefit starting as early as age 35. The findings strongly support efforts to build cardiorespiratory fitness in youth.
