Diagnosis
Athletes heart is usually an incidental finding during a routine screening or during tests for other medical issues. An enlarged heart can be seen at echocardiography or sometimes on a chest X-ray. Similarities at presentation between athletes heart and clinically relevant cardiac problems may prompt electrocardiography (ECG) and exercise cardiac stress tests. The ECG can detect sinus bradycardia, a resting heart rate of fewer than 60 beats per minute. This is often accompanied by sinus arrhythmia. The pulse of a person with athletes heart can sometimes be irregular while at rest, but usually returns to normal after exercise begins.Regarding differential diagnosis, left ventricular hypertrophy is usually indistinguishable from athletes heart and at ECG, but can usually be discounted in the young and fit.It is important to distinguish between athletes heart and hypertrophic cardiomyopathy (HCM), a serious cardiovascular disease characterised by thickening of the hearts walls, which produces a similar ECG pattern at rest. This genetic disorder is found in one of 500 Americans and is a leading cause of sudden cardiac death in young athletes (although only about 8% of all cases of sudden death are actually exercise-related). The following table shows some key distinguishing characteristics of the two conditions.Athletes heart should not be confused with bradycardia that occurs secondary to Relative energy deficiency in sport or Anorexia nervosa, which involve slowing of metabolic rate and sometimes shrinkage of the heart muscle and reduced heart volume.
A larger heart results in higher cardiac output, which also allows it to beat more slowly, as more blood is pumped out with each beat.Another sign of athletes heart syndrome is an S3 gallop, which can be heard through a stethoscope. This sound can be heard as the diastolic pressure of the irregularly shaped heart creates a disordered blood flow. However, if an S4 gallop is heard, the patient should be given immediate attention. An S4 gallop is a stronger and louder sound created by the heart, if diseased in any way, and is typically a sign of a serious medical condition. Cause
Athletes heart is a result of dynamic physical activity, such as aerobic training more than 5 hours a week rather than static training such as weightlifting. During intensive prolonged endurance or strength training, the body signals the heart to pump more blood through the body to counteract the oxygen deficit building in the skeletal muscles. Enlargement of the heart is a natural physical adaptation of the body to deal with the high pressures and large amounts of blood that can affect the heart during these periods of time. Over time, the body will increase both the chamber size of the left ventricle, and the muscle mass and wall thickness of the heart.Cardiac output, the amount of blood that leaves the heart in a given time period (i.e. liters per minute), is proportional to both the chamber sizes of the heart and the rate at which the heart beats.