By Gabe Mirkin, M.D.
Virtually all doctors agree that exercise helps to keep you healthy and to prolong your life. People who exercise into later life live longer than non-exercisers and are at reduced risk for high blood pressure, heart attacks, premature death, diabetes, strokes and even some cancers (Circulation, July 25, 2022;146(7):523–534). Endurance bicycle racers who participated in the Tour de France from 1947 to 2012 have lived an average of five years longer than their countrymen (European Heart Journal, 2013;34 (40):3145-3150).
People who exercise regularly are far less likely to develop irregular heartbeats called atrial fibrillation (European Heart Journal, July 2021;42(25):2472–2483; Circulation, April 22, 2015). However:
• Competitive athletes appear to be almost two and half times more likely than non-athletes to experience atrial fibrillation (British Journal of Sports Medicine, Oct 2021;55(21):1233-1238).
• About 20 percent of almost 1000 long-term competitive endurance athletes, mostly middle-aged men, said they had been diagnosed with atrial fibrillation (Clinical Journal of Sport Medicine May 2023, 33(3):p 209-216).
• Long-term female competitive endurance athletes are at increased risk for atrial fibrillation (British Journal of Sports Medicine, 2023;57:1175-1179).
• Older endurance cross country skiers are at increased risk for atrial fibrillation (Circulation, Aug 26, 2019;140(11):910–920).
• Extreme endurance exercisers such as bicycle racers, cross country skiers and long-distance runners who compete into their 40s and beyond may be at increased risk for atrial fibrillation (American Journal of Cardiology, October 15, 2014;114(8):1229–1233).
• The incidence of atrial fibrillation appears to be more common in older athletes than in the general population (J Am Coll Cardiol, 2005;46:690–6).
• Articles in the Wall Street Journal, the New York Times and other popular media have suggested that some athletes who continue to do extensive fast mileage or train for extreme endurance events in later life may be increasing their risk for atrial fibrillation.
What is Atrial Fibrillation?
Each heartbeat starts when a “battery” in the upper heart (atrium) sends an electrical impulse through the upper heart to make it contract to squeeze blood toward the lower heart (ventricle). Then the electrical impulse reaches another “battery” in the lower heart to make the lower heart squeeze blood forward. Atrial fibrillation means that the upper heart quivers and does not push blood forward, while the lower heart beats independently. Many people with atrial fibrillation have no symptoms and do not know that they have this condition until it is discovered during a routine physical examination. Symptoms may include:
• Palpitations (a feeling that the heartbeat is racing, uncomfortable, or irregular)
• Muscle weakness
• Reduced ability to exercise
• Fatigue
• Lightheadedness
• Dizziness
• Confusion
• Shortness of breath
• Chest pain
These symptoms are often harmless, but on rare occasions an irregular heartbeat can cause sudden death by stopping the heart from pushing blood through your body or worse, can cause a clot to form in the upper heart that travels to another part of the body to block the flow of blood to that part of the body.
Atrial fibrillation is the most common irregular heartbeat. It occurs in 1.5-2 percent of the general population, and risk increases with age. It affects 10 percent of 75-year-olds and 20 percent of those over 85, because aging increases the risk factors for atrial fibrillation such as blocked arteries, high blood pressure or diabetes.
How Atrial Fibrillation Can Harm You
When a person has an upper (atrial) heart that is fluttering, blood pools there and a clot can collect and pass to the brain to cause a stroke, or to the lungs to block blood flow through the lungs. This is so dangerous that most doctors prescribe anti-clotting agents to everyone with atrial fibrillation. I believe that athletes with atrial fibrillation are far less likely to suffer clots that cause strokes than non-athletes with atrial fibrillation, but I have not seen any studies to support my belief. Healthy athletes can have occasional irregular heartbeats that will not harm them, but at this time, doctors treat atrial fibrillation in athletes the same way they treat other patients with this condition.
Extreme Exercise May Increase Atrial Fibrillation Risk
Two studies raised the concern about extreme amounts of exercise in older athletes. In the first study, 29 elite athletes were given MRIs to look for heart muscle scarring that increases risk of atrial fibrillation. They were Olympic or national team runners and rowers who had competed throughout their lives, including some who had competed in more than 100 marathons. In the older group of 12 athletes ages 50 to 67, half showed some heart muscle scarring (J Appl Physiol, June 2011;110(6):1622-6). Those who had trained the longest and hardest had the most scarring. Neither the 17 younger athletes (20-42) nor the control group of 20 older non-athletes showed this heart muscle scarring.
In the second study, on rats, a 16-week program of daily one-hour treadmill running caused widening of the upper part of their hearts and scarring in the heart muscle that could increase risk for irregular heartbeats (J Am Coll Cardiol, July 2013;62(1):68-77). The scars in the upper heart remained after the rats stopped exercising.
Risk Factors for Atrial Fibrillation
• High blood pressure is the most significant risk factor for atrial fibrillation (Hypertension, 2012 Feb;59(2):198-204). Blood pressures greater than 140/90 significantly increased risk (J Am Soc Hypertens, 2015 Mar;9(3):191-6).
• Diabetes. High blood sugar levels can damage heart muscle itself (Cardiovascular Diabetology, Jan 18, 2020;19(9)).
• Overweight (J Am Coll Cardiol, Jul 7, 2015). A program getting people to reduce their excess body weight markedly reduced symptoms in patients who already had atrial fibrillation (JAMA, 2013;310(19):2050-206).
• Alcohol.
• Smoking.
• An over-active thyroid.
• A very low heart rate, below 50 beats per minute (Circ Arrhythm Electrophysiol, 2013, Aug;6(4):726-31).
• Abnormal coronary artery calcium score, even with no heart symptoms (Am J Cardiol, 2014 Dec 1;114(11):1707-12). This test for plaques in heart arteries can be ordered by any doctor.
• Lack of exercise. Exercise helps to prevent atrial fibrillation; fit men had a 23 percent lower susceptibility for atrial fibrillation (Am J Cardiol, 2012 Aug 1;110(3):425-32).
• Aging. The older you are, the more likely you are to suffer atrial fibrillation. Walking or cycling is associated with a decreased risk in older people (Heart, 2014 Jul;100(13):1037-42).
• Possibly extreme ultra-endurance exercise.
My Recommendations
Exercise reduces the chances of a person developing atrial fibrillation. Nobody has shown that exercise in itself causes atrial fibrillation, and it is only extreme ultra-endurance exercise that some doctors believe may increase risk for atrial fibrillation. I think that nutrition, exposure to pollutants and other lifestyle factors are also important. I do not believe that just exercising will give you adequate protection from heart disease. To protect your heart, you should follow all of the rules that apply to everyone whether you compete in ultra-endurance events, exercise moderately or just sit on a couch.
• eat lots of fruits and vegetables
• severely restrict sugar-added foods and drinks
• restrict red meat and fried foods
• avoid smoking, second-hand smoke and third-hand smoke
• restrict alcohol
• avoid overweight
• exercise
The scientific literature recommends exercise for most people, but prolonged exercise through pain and exhaustion may increase risk for atrial fibrillation. If you have, or suspect that you may have, atrial fibrillation or any heart disease, always check with your doctor first about exercising. Never ignore symptoms that could be caused by heart disease, such as:
• sudden heart palpitations
• unexplained shortness of breath
• a drop in exercise performance
• chest pain
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe’s full bio.
Joe says
I am glad to see that your opinion of the risk of AFib has evolved since your past articles questioning veracity of it in endurance athletes. The is a dose response to exercise. I’ve reduced the amount of high intensity workout and rides. I’d like to stay off NOACs like Eliquis or Xeralto or have to have a Watchman implanted
Bernard Doyle says
Dr. Merkin,
I was diagnosed with atrial fibrillation about seven years ago at age 65 and underwent various treatments for about a year before having ablation surgery which to-date has resolved the issue without any recurrence of symptoms.
I first experienced very high heart rate halfway through a 20 mile bike ride when my heart rate monitor started indicating rates in access of 210 beats per minute. When I showed my printout to my GP he referred me to a heart specialist who after confirming my atrial fibrillation by wearing a halter for a few days, put me on a drug regime to try to keep the heart rate under control. After about six months of trying different drugs with little effect and after the last drug cocktail caused my heart to stop for about seven seconds at random times, I was ordered to the Emergency Room for other measures.
My cardiologist’s first thought was to have a pacemaker implanted to control the heartbeat. I thought this was an extreme measure and held off a commitment to the surgery. My wife fortunately has a nephew who is a cardiologist in Atlanta, so I called him and after explaining the situation, asked what questions I should be asking before committing to any procedure. He told me about a rating system that cardiologists use to suggest the type of treatment that is best suited for my condition. He when over the questions that the cardiologist should ask before moving forward. The next day, I was met by a new cardiologist who quickly demonstrated that he was very familiar with my case and proceeded to answer all of the questions I had been poised to ask before I got the chance. His recommendation was that I should have ablation surgery to try to correct the condition. The third day in the hospital, I underwent the procedure which proved to be a success. I did have a few episodes of atrial fibrillation in the following two months, but since then, I have been symptom free. I’m keeping my fingers crossed that I am not going to see a recurrence, but I have been told that it could happen. I am thankful that I had someone to consult with before meeting with the surgeon and that I had such a competent and informative doctor to do the surgery.
I enjoyed your article about precursors to atrial fibrillation, I thought you might want to have another article concerning the treatments. I suspect that part of the reason that I had to go through so many drug trials was that the insurance company wanted to avoid the cost of surgery if a drug would do the job. But, I’m not sure of that. Thanks for your articles.
Aaro Paavo Heinonen says
I had my first occurrence of A-Fib in 1997. I am now 70 and continue to cycle, swim and run. I monitor the heart during any exercise and consult with a cardiologist yearly. I take no drugs. It does pop up every now and again and interestingly, I just go for a bike ride and it rights itself. I have learned that HR monitors can be bad, in that they will often misread the heart rate, especially in cold or wind conditions. Gel or my favorite, Buh-Bump is a must for every ride. I have gone as long as 15 years with no occurrence. Usually, it relates to other stresses in my life, but I try to manage sleep, identify and reduce any stressors and avoid alcohol and any dehydration. Each case is different, but they have been studying it for decades now in older endurance athletes and there is a fair amount of literature. My non scientific observation is that ablations generally do not work. The scientific literature actually backs that up. Drink a coffee everyday, or two and make sure not to reduce your salt and or electrolytes by too much.
This is just my own experience with it for the past 27 years.