Athlete's heart refers to the normal changes that the heart undergoes in people who regularly do strenuous aerobic exercise (for example, higher intensity running or bicycling) and also in those who do higher intensity weight training exercise (weight lifting).
In a person with athlete's heart
The heart is larger.
The heart walls are thicker.
The heart chambers are somewhat larger.
This increase in size and thickening of walls allows the heart to pump substantially more blood per heartbeat. The larger volume of blood with each heartbeat allows the heart to beat more slowly, which results in a slower, stronger pulse (which can be felt at the wrist and elsewhere on the body) and sometimes in a heart murmur. Heart murmurs are specific sounds created as blood flows through the valves of the heart. Although heart murmurs can also be a sign of a heart valve disorder Overview of Heart Valve Disorders Heart valves regulate the flow of blood through the heart's four chambers—two small, round upper chambers (atria) and two larger, cone-shaped lower chambers (ventricles). Each ventricle has... read more 
, some murmurs are perfectly normal in an athlete's heart and are not dangerous. The heartbeat of a person with athlete's heart may be irregular at rest but becomes regular when exercise begins. Blood pressure is virtually the same as in any other healthy person. Heart changes in women are typically less than those in men of the same age, body size, and level of training.
The heart changes that take place in an athlete's heart resemble those that can occur in certain heart disorders. For example, the heart can enlarge in hypertrophic cardiomyopathy Overview of Cardiomyopathy Cardiomyopathy refers to progressive impairment of the structure and function of the muscular walls of the heart chambers. There are three main types of cardiomyopathy: Dilated cardiomyopathy... read more 
and heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or... read more 
. Murmurs can occur in heart valve disorders Overview of Heart Valve Disorders Heart valves regulate the flow of blood through the heart's four chambers—two small, round upper chambers (atria) and two larger, cone-shaped lower chambers (ventricles). Each ventricle has... read more , and an irregular pulse can indicate an abnormal heart rhythm Overview of Abnormal Heart Rhythms Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more 
. The main differences between athlete's heart and an abnormal heart is that in athlete's heart
The heart and its valves function normally.
The person does not have an increased risk of a heart attack or other heart disorder.
The person has no symptoms. Doctors usually suspect athlete's heart during routine screening or when the person is being evaluated for unrelated symptoms.
Diagnosis of Athlete's Heart
Electrocardiography
Most athletes do not require extensive testing, but doctors usually do electrocardiography Electrocardiography Electrocardiography (ECG) is a quick, simple, painless procedure in which the heart’s electrical impulses are amplified and recorded. This record, the electrocardiogram (also known as an ECG)... read more 
(ECG) because it is important to ensure that the person does not have a heart disorder. A variety of electrical changes in the heart are detectable on an ECG. These changes would be considered abnormal in a person who is not an athlete but are perfectly normal in an athlete.
If the person has chest pain Chest Pain Chest pain is a very common complaint. Pain may be sharp or dull, although some people with a chest disorder describe their sensation as discomfort, tightness, pressure, gas, burning, or aching... read more or other symptoms of a heart disorder, more extensive testing is needed, such as echocardiography Echocardiography and Other Ultrasound Procedures Ultrasonography uses high-frequency (ultrasound) waves bounced off internal structures to produce a moving image. It uses no x-rays. Ultrasonography of the heart (echocardiography) is one of... read more 
, exercise stress testing Stress Testing Stressing the heart (by exercise or by use of stimulant drugs to make the heart beat faster and more forcibly) can help identify coronary artery disease. In coronary artery disease, blood flow... read more 
, and occasionally, cardiac magnetic resonance imaging (CMR). These tests evaluate the structure and function of the heart.
Treatment of Athlete's Heart
No treatment needed
No treatment is needed. When an athlete stops training, athlete's heart slowly disappears—that is, heart size and heart rate tend to return gradually to those of the nonathlete. This process may take weeks or months to occur. Sometimes an athlete needs to decrease or stop training for a few months to determine whether the changes disappear or further evaluation for a heart disorder is needed.
Athlete's heart is not thought to affect health in any way. The rare sudden death of an athlete Sudden Cardiac Death in Athletes An estimated 1 to 3 per 100,000 apparently healthy young athletes develop an abrupt-onset heart rhythm abnormality and die suddenly during exercise. Males are affected up to 10 times more often... read more is usually due to underlying heart disease that was not previously detected rather than to any danger resulting from athlete's heart.
