'Overdosing' on Exercise May Be Toxic to the Heart

Extreme exercise may be toxic to your heart, according to a provocative review of studies set to appear in an upcoming issue of the Canadian Journal of Cardiology. Pushing your body to the max day after day can stress your heart and raise your risk for a type of abnormal heart rhythm called atrial fibrillation, or A-fib, which ultimately can lead to heart failure or a stroke, according to the review, which analyzed 12 studies on A-fib in athletes and endurance runners. But before you fall off yo