Exercising with Atrial Fibrillation: What You Need to Know

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia worldwide, affecting over 3 million Canadians and more than 5 million people in the U.S. It’s also one of the most misunderstood conditions when it comes to exercise.

At the Online Exercise Clinic, we’re often asked:

“Is it safe to exercise with atrial fibrillation?”

“How much is too much?”

“What if my heart rate is all over the place?”

The answer isn’t always simple. It depends on whether your AF is controlled or uncontrolled, what medications you take, and how your body responds to exertion. But

in most cases, regular exercise is not only safe—it’s therapeutic.

This guide breaks down the evidence, physiology, and practical strategies for exercising with AF, so you can move forward with clarity and confidence.

Atrial Fibrillation and Exercise: The Big Picture

Atrial fibrillation (AF) is a common heart rhythm disorder where the upper chambers of the heart—called the atria—beat in a fast, irregular, and uncoordinated way. Instead of producing a steady rhythm, the electrical signals in the atria become disorganized, causing the heart to quiver or “fibrillate”.

This can lead to:

• An irregular and often rapid heartbeat

• Less efficient blood flow through the heart

• Symptoms like fatigue, palpitations, dizziness, shortness of breath, or chest discomfort

AF itself isn’t always dangerous in the short term, but over time it can:

• Increase the risk of stroke (because blood can pool and form clots in the atria)

• Lead to heart failure, especially if left untreated

• Affect a person’s exercise capacity and quality of life

AF can be occasional (called paroxysmal), last longer (persistent), or become a long-term condition (permanent). While it’s more common with age, high blood pressure, heart disease, and other medical conditions can increase the risk of developing AF.

The good news is that with proper treatment—and the right approach to exercise—many people with AF can manage their symptoms, reduce complications, and stay active safely.

Controlled vs. Uncontrolled AF: What’s the Difference?

Controlled AF

• Resting heart rate is stable (typically <100 bpm)

• Symptoms are mild or absent

• Medications (e.g., beta blockers, calcium channel blockers) or ablation therapy have stabilized rhythm or rate

• Can be paroxysmal (comes and goes), persistent, or permanent

✅ Exercise is encouraged, with appropriate monitoring and pacing

Uncontrolled AF

• Resting HR is elevated (>100 bpm) and irregular,

• Frequent episodes of palpitations, dizziness, fatigue, or shortness of breath

• Poor medication tolerance or pending intervention (e.g., cardioversion or ablation)

⚠️ Increased risk of complications or intolerance during exercise,  Wait until better rate control is achieved

❌ Avoid high-intensity or unmonitored exertion

Why Does the Risk of Complications Increase with Uncontrolled Atrial Fibrillation During Exercise?

As mentioned above, in uncontrolled atrial fibrillation, the heart rate is consistently elevated (often >100 beats per minute at rest) and irregular, even without physical activity. This creates several challenges and risks when exercising:

1. Heart Rate Becomes Even Less Predictable During Exercise

During physical activity, it’s normal for heart rate to increase to meet the body’s demand for oxygen. But in uncontrolled AF, the ventricles already beat rapidly and irregularly due to chaotic atrial signals. Adding exercise can cause the rate to spike unusually high (sometimes >180–200 bpm), which:

• Reduces cardiac output (the amount of blood pumped with each beat)

• Increases risk for symptoms like dizziness, shortness of breath, or chest pain

• Can precipitate ischemia (reduced blood flow to the heart) in those with coronary artery disease

2. Loss of Atrial Contribution (“Atrial Kick”) Is More Problematic

The lack of a proper atrial contraction in AF leads to the loss of the atrial kick—the final push of blood into the ventricles before they contract. While this is often well-tolerated at rest in controlled AF, during exercise the heart needs to pump more efficiently. Without this extra filling:

• Stroke volume (amount of blood ejected per beat) may be reduced due to inefficient ventricular filling

• Exercise capacity may be reduced

• Risk of lightheadedness or fatigue increases

3. Risk of Arrhythmia Progression or Conversion

In some cases, intense exertion during uncontrolled AF may increase the risk of:

• Worsening the arrhythmia

• Transitioning into more dangerous arrhythmias (e.g., atrial flutter, tachycardia-mediated cardiomyopathy)

• Triggering ventricular arrhythmias in those with underlying structural heart disease

4. Greater Likelihood of Exercise Intolerance and Poor Recovery

With an erratic and elevated heart rate, the heart can’t adapt to changing workloads efficiently. This means:

• You may experience exertional symptoms earlier

• Recovery after exercise may be slower and more erratic

• You may develop fatigue or dyspnea disproportionate to the effort

5. Increased Risk of Stroke Without Anticoagulation

In AF—especially uncontrolled or persistent forms—the blood tends to pool in the atria, increasing the risk of clot formation. If an individual with uncontrolled AF is not on anticoagulants (blood thinners) then exercise is contraindicated.

Bottom line: Stable AF is not a contraindication to exercise—but uncontrolled AF is a red

flag. Always check with your cardiologist or clinical exercise physiologist before

beginning or progressing an exercise routine.

What the Research Says About Exercise and Atrial Fibrillation

Moderate Exercise Lowers AF Risk and Burden

A 2019 meta-analysis (Heart Rhythm) found that individuals who engaged in regular moderate exercise had:

• 26% lower risk of developing AF

• Improved symptom scores and quality of life

• Reduced AF recurrence after ablation

One of the most significant benefits of regular moderate exercise for people with AF is its potential to reduce symptom burden and delay the onset of episodes. Research suggests that structured aerobic training can increase the “AF threshold”—the point at which exertion might trigger an episode—by improving cardiac autonomic regulation (how your nervous system automatically controls your heart rate), atrial remodeling, and overall cardiovascular fitness.

A pivotal randomized controlled trial, the CARDIO-FIT study (Pathak et al., JACC, 2015), demonstrated that patients with paroxysmal or persistent AF who engaged in a structured exercise program aimed at improving cardiorespiratory fitness experienced:

• Significant reductions in AF symptom frequency and severity

• A two-fold increase in arrhythmia-free survival over five years

• Fewer recurrences even without antiarrhythmic drugs

Mechanistically, exercise may:

• Reduce left atrial size and pressure, mitigating substrate for AF

• Enhance vagal-sympathetic balance (keeping the heart rate and stress response in balance), improving heart rate variability

• Increase the threshold of adrenergic or exertional triggers that would otherwise induce AF

• Improve endothelial function (elasticity of arteries) and reduce systemic inflammation, both of which are involved in AF pathogenesis

In short, consistent moderate exercise can help stabilize the heart—making it more resilient to irregular rhythms and improving both functional capacity and quality of life.

Athletes and Atrial Fibrillation

It is not fully conclusive, but there is growing evidence that long-term, high-volume endurance exercise (like years of marathon running, cycling, or triathlons) is associated with an increased risk of developing atrial fibrillation (AF)—especially in middle-aged and older men.

However, this does not mean that endurance exercise is harmful for most people or that it should be avoided. The relationship is complex, and moderate exercise still clearly reduces AF risk and improves overall cardiovascular health.

What the Research Shows:

1. Elevated AF Risk in Endurance Athletes

Studies show that veteran endurance athletes—particularly those who have trained intensely for many years—have 2–5 times higher rates of AF compared to the general population.  This association is most consistently seen in males athletes, masters athletes (40+ years), and those with a long training history (eg. Decades of high-intensity, high volume aerobic training)

2. Mechanisms Likely Driving This Risk

While the exact cause isn’t fully settled, researchers believe the following contribute:

• Atrial enlargement and fibrosis (scar tissue) from repeated volume and pressure overload

• Increased vagal tone, which can predispose the atria to electrical instability

• Frequent premature atrial contractions (PACs), a known AF risk factor

• Inflammation and oxidative stress from extreme endurance activity

3. Threshold Effect

Moderate exercise is protective against AF and reduces cardiovascular risk.  Very high levels (especially >1500–2000 MET-hours/year or > 5–10 hours/week of high-intensity endurance training) may cross into a zone where AF risk begins to rise again—a “U-shaped” relationship.

Despite some evidence of increased risk with long term high-intensity high-volume exercise, it is important to note that the absolute risk of AF is still relatively low for most people.  Even in athletes who develop AF, their overall risk of stroke, heart attack, or death is lower than sedentary individuals, likely because of their higher baseline cardiovascular fitness.

How to Exercise Safely with AF

Start with Aerobic Activity

Moderate aerobic activity is foundational for AF management.

Target:

• Frequency: 3–5 days/week

• Duration: 20–45 minutes/session

• Intensity:

• Borg RPE Scale: 11–13 (“light to somewhat hard”)

• Should achieve a notable increase in your breathing

Incorporate Resistance Training

• Frequency: 2–3 non-consecutive days/week

• Type: Bodyweight, bands, or machines

• Intensity: Light to moderate, 1–3 sets of a weight that elicit muscular fatigue within 10–15 repetitions

Benefits include improved muscular strength, blood pressure control, insulin sensitivity, and balance—all protective in AF populations.

Special Considerations for Exercising with Atrial Fibrillation

When exercising with atrial fibrillation, a few important precautions can help ensure safety and effectiveness. First, heart rate monitoring is often unreliable in AF because of the irregular and sometimes rapid rhythm. Additionally, medications like beta blockers or calcium channel blockers blunt the heart rate response, making devices like fitness trackers or chest straps inaccurate. Instead, patients should use the Borg Rating of Perceived Exertion (RPE) scale or the talk test to guide intensity.

If you are on oral anticoagulants (e.g., apixaban, rivaroxaban, warfarin), take extra care with contact sports or activities that carry a high risk of falling, such as downhill skiing or mountain biking. These activities may increase your risk of internal bleeding or injury if a fall occurs.

Perhaps most importantly, anyone with uncontrolled AF—characterized by a rapid resting heart rate, frequent palpitations, or exercise-induced symptoms—should not engage in unsupervised or high-intensity exercise until the condition is medically stabilized. Even in stable AF, close symptom monitoring is crucial: if you experience chest discomfort, dizziness, sudden fatigue, or sustained palpitations, stop the session and seek medical advice.

Final Thoughts: Exercise is Essential—But Individualized

Living with atrial fibrillation can feel unpredictable. One day you’re full of energy, the next you’re fatigued by a flight of stairs. The key is to anchor your routine with science-based structure, listen to your symptoms, and work with professionals who understand your condition.

• Exercise is recommended and considered safe for most individuals with stable atrial fibrillation.

• The focus should be on improving cardiorespiratory fitness, which is associated with reductions in AF burden and symptom severity.

• Individualized prescription is critical, especially in those with:

• Uncontrolled ventricular rate

• Poorly tolerated symptoms

• Underlying structural heart disease

At the Online Exercise Clinic, we always recommend an individualized approach to exercise in AF, ensuring that your program is aligned with your current rhythm status,medications, and overall cardiovascular risk. If you have any questions please contact us.

The information in the blog is provided for informational and educational purposes only and does not constitute medical advice.  The information is not a substitute for professional medical advice, diagnosis, or treatment.  For questions please follow up with your healthcare professional.