Sudden Cardiac Death During Exercise: Assessing Risk
Intense exercise can expose an undiagnosed heart condition. Learn how symptoms, age and family history guide the choice of cardiac checks before training.
Sudden cardiac death during exercise can occur when intense activity triggers a dangerous arrhythmia in someone with an undiagnosed heart condition. Regular physical activity reduces cardiovascular and overall mortality, but assessment before intensive training should consider each person's individual risk.
European Society of Cardiology guidance notes that sudden cardiac death in younger athletes is more often linked to inherited or congenital conditions, including cardiomyopathies, electrical heart disorders and coronary artery anomalies. After 35, the pattern changes: atherosclerotic coronary artery disease accounts for more than 80% of cases in athletes in this age group.
Which history matters when assessing sudden cardiac death risk?
Assessment of sudden cardiac death risk starts with symptoms and family history. Fainting, dizziness, chest pain or pressure during exercise, unusual breathlessness, palpitations and a sudden reduction in exercise tolerance should be discussed with a doctor. Family history matters, especially sudden death, cardiomyopathy or serious arrhythmias in close relatives.
What does a resting ECG add?
A resting 12-lead ECG can improve detection of potentially important cardiovascular conditions. European sports cardiology has traditionally placed considerable emphasis on it, including the Italian screening experience reported by Domenico Corrado and colleagues.
The 2025 AHA/ACC scientific statement also notes that adding ECG improves detection of hidden heart conditions compared with history and physical examination alone. An athlete's ECG must be interpreted using appropriate athlete-specific criteria.
Is echocardiography necessary for everyone?
Echocardiography is not a mandatory screening test for every asymptomatic athlete; its use is determined individually. It assesses chamber size, heart muscle thickness, ventricular function and valves, and can identify a range of structural conditions.
When is exercise testing useful?
Exercise testing evaluates the heart's response during physical activity as well as at rest. A treadmill or cycle test can show heart rhythm and blood pressure responses, ECG changes and the development of symptoms.
Stress echocardiography adds assessment of heart muscle contraction during stress and can provide additional information in selected clinical situations. In the study by Galanti and colleagues cited here, diagnostic accuracy was 71.7% for exercise ECG and 94.3% for stress echocardiography. These figures are results from that study rather than a guarantee of performance for every patient. Where indicated, further assessment may include Holter monitoring, cardiopulmonary exercise testing, cardiac MRI, coronary CT angiography or genetic testing.
No investigation can guarantee that sudden cardiac arrest will not occur. AHA/ACC also emphasizes access to an automated external defibrillator and cardiopulmonary resuscitation skills at training venues. The aim of assessment is to understand heart health and individual risks and to make training safer.
Are blood tests needed before training?
There is no single mandatory blood panel for every healthy person before exercise. Laboratory assessment can, however, identify factors affecting exercise safety and tolerance.
Electrolytes such as potassium, magnesium and calcium are relevant. A marked imbalance can affect the electrical stability of the heart and increase arrhythmia risk, particularly during intensive training, dehydration and substantial fluid loss through sweating.
A complete blood count, ferritin, lipid profile, glucose or HbA1c, and kidney function may also be assessed according to age, symptoms and individual risk factors. Blood tests complement cardiac assessment; they do not replace ECG, echocardiography or evaluation during exercise.
How are heart checks before exercise planned?
At Longevium Clinic, we can assess cardiovascular health before someone starts or increases their exercise: consultation, ECG, echocardiography, exercise testing, stress echocardiography and assessment of physical capacity. The findings help the doctor determine whether further investigations are needed and what level of exercise is appropriate. This is particularly relevant when returning to sport after a long break, preparing for intensive training or competition, or planning serious training at 35–45.
Our Longevity Day page describes the broader health assessment programme; the doctor determines which checks are appropriate. For more on evaluating exercise capacity, read about VO₂ max and cardiopulmonary exercise testing.
Author: Dr. Yulia Marshintseva, MD, PhD — General Practitioner, Longevity Physician.