Athletic heart syndrome

Overview

Athletic Heart Syndrome (AHS) is a benign physiological condition characterized by structural and functional changes in the heart as a result of prolonged and intensive athletic training. It is most commonly seen in endurance athletes such as long-distance runners, swimmers, and cyclists. These changes include enlargement of the heart chambers, thickening of the heart muscle walls, and slower resting heart rates.

AHS is not a disease but a normal adaptation of the cardiovascular system to increased physical demands. However, it must be distinguished from pathological conditions like hypertrophic cardiomyopathy to avoid unnecessary concern or misdiagnosis.

Causes

Athletic Heart Syndrome results from the body's adaptation to repetitive, high-intensity cardiovascular exercise. Prolonged training increases the heart's workload, prompting the heart to remodel itself to improve efficiency. Key changes include:

• Increased left ventricular mass and volume

• Enhanced stroke volume (amount of blood pumped per beat)

• Bradycardia (slow resting heart rate)

These adaptations allow the heart to pump more blood with fewer beats, increasing oxygen delivery to muscles during prolonged exertion.

Symptoms

Most individuals with Athletic Heart Syndrome are asymptomatic and feel completely healthy. However, some features may include:

• Low resting heart rate (often below 60 bpm, sometimes as low as 30–40 bpm)

• Heart murmurs on physical exam (due to increased blood flow)

• Enlarged heart visible on imaging (echocardiogram or chest X-ray)

• ECG changes such as sinus bradycardia or early repolarization

These signs are benign in athletes and should not be mistaken for heart disease unless accompanied by concerning symptoms like chest pain, fainting, or family history of cardiac conditions.

Diagnosis

Diagnosis of Athletic Heart Syndrome is based on clinical evaluation and ruling out pathological heart conditions. Diagnostic steps may include:

• Medical and exercise history: To assess training intensity, duration, and frequency

• Physical examination: Identifies bradycardia or flow murmurs

• Electrocardiogram (ECG): Shows benign changes related to athletic conditioning

• Echocardiogram: Detects structural heart changes such as chamber enlargement and wall thickening

• Cardiac MRI: May be used to further assess the heart if hypertrophic cardiomyopathy is suspected

• Deconditioning test: Athletes may be asked to stop training for several weeks; reversal of cardiac changes confirms AHS

Treatment

No treatment is required for Athletic Heart Syndrome, as it is a normal and healthy adaptation. However:

• Athletes should undergo regular cardiac evaluations if engaging in high-level competition

• Deconditioning (cessation of intense exercise) for 3–6 weeks can help confirm the diagnosis if uncertainty exists

• Education is important to reassure patients and distinguish AHS from true heart disease

If any abnormal symptoms such as chest pain, syncope, or irregular heart rhythms develop, further evaluation by a cardiologist is essential.

Prognosis

The prognosis for individuals with Athletic Heart Syndrome is excellent. It does not lead to long-term complications or increase the risk of cardiovascular disease. Key points include:

• Cardiac changes are reversible with detraining

• AHS does not impair athletic performance

• No increased risk of sudden cardiac death if properly differentiated from pathological conditions

With proper monitoring, athletes with AHS can continue to train and compete safely.