An exercise-induced arrhythmia is an irregular heartbeat that occurs during or right after physical activity. While it is normal for the heart to beat faster with exertion, an arrhythmia is a rhythm that becomes erratic, too fast, or too slow. The heart’s electrical signals, which orchestrate the heartbeat, can be disrupted by physical exertion. This response may be a harmless event, but it can also indicate an underlying health issue.
Identifying Symptoms
A common symptom is heart palpitations, which may feel like a fluttering, racing, or pounding in the chest. Some people describe the sensation of a skipped beat, felt as a “thump” in the chest. These are often premature contractions, where an extra beat disrupts the normal rhythm.
Beyond direct heart sensations, other symptoms can arise from the heart’s inefficient pumping. Dizziness or lightheadedness may occur, and in more serious instances, a person might faint (syncope). Another sign is unusual shortness of breath out of proportion to the exercise intensity. Chest pain or discomfort can also accompany these episodes. Experiencing any of these symptoms, especially fainting or chest pain, warrants a medical consultation.
Potential Underlying Causes
The causes of an exercise-induced arrhythmia range from temporary triggers to permanent structural or electrical problems within the heart. Dehydration and imbalances in electrolytes like potassium and magnesium can provoke an irregular rhythm. The use of stimulants, such as caffeine or ingredients in pre-workout supplements, may also contribute.
In other instances, the arrhythmia points to a problem with the heart’s physical structure. Coronary artery disease, where arteries supplying the heart become narrowed, is a significant cause. Exercise increases the heart’s demand for oxygen, and if blood flow is restricted, it can trigger an arrhythmia. Other structural issues include cardiomyopathy (a weakening of the heart muscle) and diseases affecting the heart valves.
Sometimes, the heart’s structure is normal, but its internal electrical system is faulty. These primary electrical conditions can be inherited. Conditions called channelopathies, which affect the tiny ion channels that control the heart’s electrical impulses, can cause arrhythmias during exertion. For example, certain types of long QT syndrome can result in a dangerous arrhythmia when the heart rate is high.
The Diagnostic Process
To determine the cause and significance of an exercise-induced arrhythmia, the evaluation begins with a consultation to describe symptoms, review your medical history, and a physical examination.
An electrocardiogram (ECG or EKG) is a test that records the heart’s electrical activity at rest and can reveal underlying abnormalities. However, since the arrhythmia occurs with exertion, it may not be present during a resting ECG. For this reason, an exercise stress test is often performed. During this test, you walk or run on a treadmill while connected to an ECG, allowing the doctor to observe the heart’s electrical response to physical stress.
If the arrhythmia is infrequent, an ambulatory monitor may be used. A Holter monitor is a portable ECG worn for 24 to 48 hours to record the heart’s rhythm continuously. An event monitor is similar but may be worn for longer, and you activate it when you feel symptoms. To investigate potential structural causes, a doctor may order an echocardiogram, which uses ultrasound to create detailed images of the heart’s muscle, chambers, and valves.
Medical Management and Exercise Modifications
A management plan is tailored to the arrhythmia’s specific cause and severity and is developed with a cardiologist. For some, treatment involves medication. Beta-blockers are a class of drugs often used to slow the heart rate and reduce the likelihood of an arrhythmia.
For more complex arrhythmias, procedural interventions may be necessary. Catheter ablation is a procedure where a thin tube is guided to the heart to deliver energy that scars the small area of heart tissue causing the faulty electrical signal. In cases where the arrhythmia poses a high risk, an implantable device might be recommended. Pacemakers can correct a slow heartbeat, while implantable cardioverter-defibrillators (ICDs) can detect and stop dangerous, fast arrhythmias.
A diagnosis does not automatically mean an end to physical activity. Instead, a doctor will provide guidance on how to exercise safely. This often includes thorough warm-ups and cool-downs. Maintaining proper hydration and avoiding known triggers like stimulants are also important modifications. Your doctor may also recommend adjusting the intensity or type of exercise you perform.