Exercise has an impact on every organ in your body, but the one it most profoundly affects is your heart. No surprise here! Your heart has the demanding task of pumping blood and oxygen to the muscles you’re working – and it never sleeps. It contracts like clockwork, propelling life-giving blood and oxygen to your tissues even when you are at rest or sleeping. During exercise, the demands for oxygen increases even more. It makes sense that your heart would adapt in such a way to make it more efficient. Sometimes, these changes are structural and lead to a condition called athletic heart syndrome.
Understanding Athletic Heart Syndrome
Athletic heart syndrome describes changes that occur to the heart in athletes and people who do a high volume of exercise, usually 7 or more hours of exercise each week. This condition was first recognized in 1899 when S. Henschen compared the hearts of cross-country skiers to subjects who did little exercise and noted differences in heart size. The cross-country skiers had larger hearts than their sedentary counterparts.
Athletic heart syndrome is silent and doesn’t typically cause symptoms or health issues. It’s simply the heart’s way of adapting to the stress of exercise. However, some of the changes the heart undergoes may resemble changes to the heart that happen in people who have uncontrolled high blood pressure or other forms of heart disease. So, it’s important for physicians to be able to distinguish between athletic heart syndrome and other types of heart problems.
Structural Changes to the Heart in Response to Exercise
With athletic heart syndrome, the heart changes somewhat in structure. With frequent exercise, the walls of the heart chambers thicken. Your heart has four chambers composed of two atria and two ventricles. The ventricles are larger and make up the lower chambers of the heart. It’s the left ventricle that pumps freshly oxygenated blood from the lungs to the body while the right ventricle collects blood from the body and pumps it back to the lungs for it to pick up more oxygen.
In people with athletic heart syndrome, the left ventricle becomes thicker, so it can generate more force and more efficiently pump blood to the body and the muscles and tissues that need it. It’s not uncommon for the left ventricle to increase in thickness by 15 to 20% in people who train frequently. So, an athlete or anyone who does a high volume of exercise might have a heart that’s larger than normal with a thicker left ventricle. Studies also show that the right ventricle thickens to some degree as well.
Changes in Heart Function
What about functional changes? If you have an athletic heart and the walls of your ventricles are thicker, your heart becomes a more efficient pump and can propel more blood to tissue of the body with each beat. As such, it doesn’t have to pump as many times per minute to meet the body’s oxygen demands. That’s why heart rate is often significantly slower in those who have an athletic heart. A normal resting heart rate is between 60 and 90 beats-per-minute, whereas an athletic heart may beat 50 beats-per-minute or even less. Highly trained athletes may have a resting heart rate as low as 30 beats-per-minute.
Who Develops an Athlete’s Heart?
As mentioned, exercise volume is a factor. Training an hour-a-day most days of the week is usually the minimum volume of exercise needed to see structural changes to the heart. Structural changes to the heart also differ with the type of exercise you do. A Harvard study found that subjects who did endurance exercise and strength trained both experienced enlargement of their hearts. But, the endurance athletes showed expansion of both ventricles, while the left ventricle thickened but didn’t expand in the strength athletes. Both forms of exercise impact heart structure but the changes differ with the type of exercise.
How Do You Know if You Have an Athletic Heart?
Most people become aware that they have athletic heart syndrome after a routine chest x-ray shows enlargement of the heart. Athletic heart syndrome doesn’t always show up on a chest x-ray, but another type of imaging test, called an echocardiogram typically reveals it. An echocardiogram can also usually differentiate between an enlarged heart due to exercise and one related to other heart problems. A physician may also note changes on an electrocardiogram, or EKG, a tracing of the heart’s electrical activity. The most common abnormality is a slow heart rate, although other abnormalities can show up as well.
Is Athlete’s Heart Harmful?
Fortunately, the structural and functional changes associated with athlete’s heart syndrome are usually harmless and don’t place you at higher risk of sudden death or other heart-related events. However, it’s important to distinguish athlete’s heart syndrome from other heart problems that can increase the risk of sudden death. Studies to explore further might include an echocardiogram or stress testing.
If you have heart enlargement and thickening of the ventricles due to athlete’s heart, the size of the heart and the ventricles typically becomes smaller if you stop exercising as there’s no longer a demand for greater blood and oxygen delivery. However, about one out of five athletes with athlete’s heart syndrome who stop exercising have some degree of thickening of the ventricles and enlargement of the heart that doesn’t regress. This may be a red flag that there are other undiagnosed heart problems.
The Bottom Line
If you exercise more than seven hours per week, you, too, may have athlete’s heart syndrome. In most cases, it’s nothing to worry about but it’s important to distinguish it from more serious heart problems. Most importantly, if you have unexplained symptoms, like shortness of breath, chest discomfort, lightheadedness, or dizziness during exercise, see your physician.
References:
J Tehran Heart Cent. 2010 Winter; 5(1): 1–8.
Circulation: Cardiovascular Imaging. 2015; 8: e002086.
The Harvard Gazette. “Exercise changes structure of heart”
Med Sci Sports Exerc. 1988 Oct;20(5 Suppl): S146-51.
Medical News Today. “Weight Training Has Unique Heart Benefits, Study Suggests”
Merck Manual Professional Version. “Athlete’s Heart”
Related Articles:
Enlarged Hearts in Athletes: Is It Athlete’s Heart?
Does Your Heart Change Structurally in Response to Exercise?
Great post. Especially For people like me who have high blood pressure. However, exercise has brought my blood pressure down along with weight loss. My cardiologist is extremely happy with my results. Like the article says check with your doctor always