Atrial Fibrillation while Running

Also known as AFib or AF, Atrial Fibrillation is the most common arrhythmia among professional and recreational athletes. According to the research, the middle-aged athletes engaged in endurance sports (skiers, cyclists, runners, etc.) are more prone to AF than others.

The exact mechanism of onset and progression of atrial fibrillation in athletes is complex and includes factors like atrial ectopy and usage of certain sports supplements. The condition usually arises in those whose heart muscle is affected by certain pathological processes (atrial remodelling, inflammation, fibrosis, etc.). Conditions like electrolyte imbalance caused by excessive sweating and/or gastroesophageal reflux disease can modulate the AF triggering particularly unpleasant episodes of cardiac arrhythmia.

The treatment of atrial fibrillation in general population is easy and inducing “the first line drugs” almost always leads to satisfying therapeutic response. On the other hand, treating a cardiac arrhythmia in an athlete is a challenge that requires special attention- putting the heart rate under control (this usually means slowing the heart down) means lower athletic performance. The catheter ablation, although a method that provides an excellent treatment results, is not suitable for all athletes.

By the end of this article you will learn about AF in endurance training, what can you do about it and how serious the condition is.

What are the symptoms of Atrial Fibrillation?

The typical symptom is fluttering or thumping heartbeats. Patients describe AF differently. The common denominator is the feeling of prolonged, fast-paced pulsating sensation in the chest. AF feels something like a sequence of skipped heartbeats.

Uncommon symptoms include dizziness, weakness, sweating, fatigue while exercising, faintness, anxiety, shortness of breath and general fatigue. Paying attention when these symptoms occur is particularly important- is there a clear correlation between physical activity and their onset?

The abovementioned symptoms can be a sign of other health issues as well. Differing between dizziness that’s caused by AF and the one caused by some other health issue without additional diagnostic tools (such as ECG) can be a challenge even for an experienced clinician.

Some people have AF, but don’t have any symptoms- they are asymptomatic. In such cases, AF is diagnosed on a routine medical check-up (this is why it’s vital to perform yearly medical check-ups!).

Keep in mind that chest pain or squeezing sensation in the chest may be a sign of a heart attack or angina pectoris. These symptoms require immediate medical help!

What makes Atrial Fibrillation so dangerous?

Atrial Fibrillation is an irregular and very fast movement of heart atria. Such movements affect blood flow and cause blood clots inside a heart. Once formed, these clots stay attached to the walls of atria, but as the heart goes back to normal rhythm sinus rhythm), they detach and move through heart chambers, aorta and other smaller blood vessels throughout the body.

When the diameter of a blood vessel levels up with the diameter of a blood clot, the clot gets stuck and obstructs blood flow. If something like this happens in a brain, the stroke will occur. Most often, the clot gets stuck in a small blood vessel somewhere in the body not causing any harm.

Basically, “entering the AF” is not as dangerous as the moment of “going back to sinus rhythm” since that’s the moment when blood clot starts its unpredictable journey through the body. Knowing this, staying in a state of permanent AF sounds like a good idea? It’s not that simple, and it’s not that good idea.

Keep in mind that, in most cases, AF is just a consequence of structural changes in the heart muscle. Structural changes themselves can cause heart failure independently of AF.

Two faces of endurance training

According to some studies, endurance training is beneficial to cardiovascular health and overall well-being. Some researchers state that endurance training can be used as a prevention for stroke since it increases the blood flow through brain improving overall vascular supply. The growing body of evidence indicates that top-level athletes live longer and have a lower risk of developing cardiovascular diseases and cancer.

Other researchers came to a different conclusion: long-term endurance sports activity (or highly demanding occupational activity) increases the risk of AF. The explanation probably lies in the fact that vigorous physical activity causes abovementioned structural changes (atrial remodeling, inflammation, fibrosis, etc.) in the heart muscle causing AF.

While the professional athletes have no other choice but to face the risk of AF, the further research should reveal what is the “optimal amount of endurance training” for recreational athletes. The optimal amount of endurance training lies in a sweet spot in which the benefits of exercise outweighs the risk of AF.

Managing the AF caused by vigorous physical activity

As mentioned in the intro, using the rate or rhythm control medications in athletes is a challenge with many limitations.

The first step in the management is identifying overtraining athletes

Temporary cessation of exercise and reduction of physical activity can decrease and in some cases prevent episodes of AF. The reduction of physical activity and sports abstinence improves symptoms of AF. Diagnosing and treating AF should be done under the supervision of health professional. It’s impossible to give a definitive answer for how long an athlete should abstain from sports or how much the physical activity should be reduced because the decision depends on many parameters that vary among different individuals.

Assessing the athlete diagnosed with AF

The recommendations made at the conference in Bethesda are as follows: Athletes with asymptomatic AF can safely participate in any sports activity as long as there are no structural changes in the heart muscle, the ventricular rate is appropriate, and the functional capacity of the heart is preserved while the athlete’s heart is in sinus rhythm. This might be a bit confusing recommendation for a layman, but the good thing is that health professionals around the world have a (not so clear) recommendation about how to assess the athlete with AF.

There is no such a thing as a conclusive answer on how to treat AF in athletes

The definitive decision physicians make is based on their own experience, clinical judgment and the lack of evidence. What we know so far for sure is that among athletes with diagnosed AF, decreasing the volume and intensity of physical activity is recommended.

The Bottom Line

Atrial Fibrillation is the most common cardiac arrhythmia in recreational and professional athletes. Some people have symptoms of AF, others do not (asymptomatic patients). The presence of symptoms does not correlate with the severity of AF- asymptomatic athletes may be at higher risk of health complications than those who suffer symptoms (thumping heartbeats, dizziness, faintness, etc.).

According to some studies, endurance training is recognized as a risk factor for AF, while other researchers claim it is beneficial for the health of cardiovascular system. The conclusive answer to its safety is yet to be found, but so far it seems that there is a “sweet spot” in a recreational sport where the endurance training benefits outweigh the risk for developing AF. Where exactly the sweet spot lies is yet to be discovered.

Treating it includes reduction of intensity and volume of physical activity. For athletes diagnosed with AF, probably the best decision would be to seek for the help of an experienced cardiologist in the field of sports medicine.


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