Effects of excessive endurance activity on the heart.

Regular moderate exercise confers many cardiovascular and health benefits. Because of this, endurance sports events have become very popular with participation increasing tremendously over the past few years. In conjunction with this increase in popularity and participation, people also have increased the amount that they exercise with many training for and competing in ultraendurance events such as ultradistance running events, iron distance triathlons, or multiday races. This excess endurance activity may appear to increase the risk of cardiac abnormalities, which may increase the risk for long-term morbidity or mortality. While it is known that moderate exercise has benefits to cardiovascular health, ultimately, the long-term cardiac effects of excessive endurance activity are unclear. What is clear, however, is that moderate exercise is beneficial, and to date, the evidence does not support recommending against physical activity.