I trained twelve hours a week for twenty years just to stay lean: at 54, a routine check-up showed what those hours had done to one chamber of my heart
A fit 54-year-old’s routine heart scan revealed an enlarged left atrium—a pattern cardiologists now recognize in lifelong endurance athletes. After two decades of consistent training, the heart adapts in ways that mirror disease. Here’s what the science shows and what you should actually do about it.