AF Association
12,873 members15,709 posts

AF in Endurance athletes

Hi there

I recently got diagnosed with AF after an endurance event. I'm an endurance athlete and have been competing for many years racing in Ironman Triathlons and am also a member of the 100 Marathon Club.

I consider myself to be pretty healthy. Its quite a shock to be informed that you have the condition. Its also very daunting to come to terms with, become more informed about and what to expect.

I'm wondering if any other athletes have had the same experience and how people have managed it?

30 Replies

There are quite a few endurance athletes who post on here and also some knowledgeable folk who will no doubt shed light on the possible link between A.F. and endurancesport. In the meantime let me say a big welcome. I can ensure you that you have come to the right forum and you will never feel alone with A.F. x


I'm not exactly an endurance athlete. Done a couple of triathlons but normally I bike and swim. Had an number of Afib attacks while biking. Not fun!!! Afib put a crimp in my work outs. Due to the meds I need to take for not only the Afib but my stents my endurance and recovery time has changed for the worse. I can still do what I was doing but I am more aware of not pushing myself to the point where I go into a full blown Afib attack. i'm not where I was before. Don't know if I ever will be . It's not the end of the world. Each persons' recovery is different. You get to know your body more and what it can do and can't do. Keep reading ,ask questions and talk to your doctors about your lifestyle. Hopefully, you'll find one that understands what you want and doesn't put you in the cookie cutter slot.


The link is well known between over exercise and AF. You may not think you are an endurance athlete but most people will.

It is thought that the training causes enlargement of the atrium which allows rogue pathways to form.



I'm far from being an endurance athlete but running and cycling when I'm in AF is impossible. It doesn't stop everyone though and you might like to read this blog



I am probably considered to be an endurance athlete (I use the term "Athlete" Loosely)

I am 16 times an Ironman, several half and other tris, raced bikes for a few years before that, didn't start any of this till I turned 40 am now 53.

I had my first Afib about 2.5 years ago got cardioverted back into rhythm after 6 weeks, went off all drugs, was good for 2 years finished 6 ironman races in that time, went into Afib again in the run leg of ironman last December with about 10k to go, walked to finish line. I fuelled myself on caffeine and was probably dehydrated that day, so I don't think that helped.

I got cardioverted again, had an Ablation in march and have been told to go back to what I used to do. So fingers crossed, I will see how I go, so hopefully its not all doom and gloom. I will probably still do Ironman for the fun of it, without keeping my heart rate in the 150's for hours on end.

There are lots of articles on Afib and Athletes.

Good luck with your sport


Thanks for your reply, it's great to hear everyones advice!

I'm in my early 40's and have completed 18 Ironmans. I've been racing Ironman for the last 10years along with marathons and ultras. Its very interesting to hear you were taking caffeine and dehydrated! I'd been on a 100m ride, only taken one bottle of electrolyte drink and very dehydrated when I went into AF. I only realised 2 days later when my heart rate was in the 80's when resting. My resting HR would be around the mid 40's. I've read that dehydration, poor sleep can be a trigger of AF.

It's great to hear that you've continued racing. I'd be interested to know how you managed the AF during training and racing? Do you know when you're having AF, what are the signs and how do you manage it if you get an episode out training?

Looking back I think I might of had a few AF episodes. I've been in the lead pack during a race and suddenly struggle to keep up with the back end of the race. I'd then race the following weekend and have no symptoms at all.

Being recently given a cardioversion and diagnosed with AF its very daunting to try and get back to any training, but it's also dangerous not to.

I've read fit muscle turns to fat when not used, including the heart and going from being relatively fit to doing nothing can be even more dangerous. How did you get back to and maintain your training?

Thanks for your reply, it's really useful along with all the replies and experiences on the blog!


Sounds similar to my first episode, I had been very dehydrated a day before I noticed, I have resting heart rate of low 40's also, noticed my hr was pretty high, started wearing hrm resting was around 90, walking put it up to 120.

After I got cardioverted I was pretty good went back to training, really took care with my hydration for training and racing, every now and again during big efforts, I would notice a spike in HR from about 170 upto 210 and feel like a couple of squirrels were having a fight in my chest, get scared slow right down and after a minute or 2 everything would be back normal. So was never sure it was an AF episode. On here you here about people who are in and out of AF all the time I think I am pretty lucky I have long breaks between episodes.

Last December I wanted a bike PB so ate caffeine gels and drank caffeine drinks, then spent 5 hours at average heart rate of mid 150's, didn't concentrate on my hydration and got dehydrated then went into AF during the run.

Now am back training, but is scary during efforts on group rides, if I think is too much for too long, I let them go, but am getting more confident every week that all is well again. It is only 9 weeks after ablation so is still big in the back of my mind, as time goes and everything stays on track, I will hopefully get more confident again.


I trained for and ran 4 marathons, all since I was 50 (58 now). I wouldn't call myself an endurance athlete compared to some. AF struck about three years ago and was largely exercise induced. It used to come on within 30 seconds or so of setting off on a run and latterly happened on every run. I had a successful ablation 11 months ago and since then I've been AF free. My EP however, has advised capping my running at 10 miles, which I'm happy to do. Having spent months with AF's iron grip sharing every run with me and consequently not really enjoying them, I'm just so happy to be out running with a normal heart beat. I still do my training - I just don't do long distances any more. Occasionally (like this last weekend watching the London Marathon on TV), I feel a little wistful and actually 10 mile races just don't give the buzz of a marathon, but honestly, I think I'd be pretty stupid to go back to running marathons and possibly undo all the good work that was done in the ablation. There are worse things in life to have given up. Good luck with your journey wherever it takes you.

1 like

Hi thanks for your reply!

Thats great that you had a successful ablation and are running. I know exactly how you feel, watching London Marathon on TV was hard. Knowing that I would have been there running and seeing friends finishing on TV..

I'm really interested to know what your symptoms are like when you're out running. How do you know when you're in AF? Since my AF I regularly wear my Heart Rate monitor and keep any eye on everything.

It' a all very new to me and I'm learning daily.

Thanks again!


Hi 100MarathonRunner. I could feel my heart going into AF, almost like someone was squeezing my heart and I could feel the power going out of my legs. I'd carry on running but just found it such an unpleasant experience with AF. Heart rate monitors didn't really help as the overall rate wasn't excessive, it was just the irregularity. I"m just so relieved to be, touch wood, free of it now. Sue


Check out Dr John M's website. He is an EP and a competitive athlete who also suffers PAF. Lots of evidence linking endurance sport and AF. You are not alone!


Hi! Welcome to the forum. I have trained and competed in sport since the age of 8. My sports have mainly been contact, but two years ago at the age of 41 I was going through exactly the same as you. In fact everybody on this forum whether they are athletes or not will have gone through exactly the same as you. There is a lot to learn about AF, but you'll find many an answer on this forum. I say answer more like peoples experiences. One thing you will learn pretty quickly is AF tends to be different for most people.

When I was diagnosed with PAF I was given medication that worked pretty well for a while and it didn't stop me doing any of my sports. I then developed a side affect to the medication and my sporting activities were placed on hold for about 6 months. I had an ablation about 9 weeks ago and I'm back in full swing (Well not at the mo, as I have torn ligaments in my foot after an over zealous tackle :) )

Having AF is not the end. Being a triathlete you may be aware of Karsten Madsen. He's got AF, have a look at this link.

Haimar Zubeldia (Cyclist), Tom James (Olympic Rower) & Mardy Fish (Tennis) all have AF and still compete.

I guess what I'm trying to say is read as much as you can about AF and just be aware of your body. I'm not sure where you stand on supplements, but certain supplements I have stopped as I noticed they induced my AF. You're on a big learning curve as I was, but this damn condition hasn't stopped me doing what I love, yet.

Take care and all the best.


1 like

Thanks Jason, I really appreciate yours and everyones replies! I'm really glad to have found the blog and hear everyones experiences and advice. As you say everyone experience is different and I value all the information!

I wasn't aware that so many people experience AF.


Hi there , I'm no endurance athlete I love running tho especially my Sunday morning 7 miler with the dogs through the woods , I got diagnosed with paroxomol af last September after not being able to run more than one mile on such a Sunday morning , my ep has told me not to run but jogging would be ok although I do struggle with the meds I'm on I've just started back jogging after having lots of af at Christmas , but any things better than not runing at all , my af doesn't come on when exercising usually wake up in af randomly , it is scary and life changing but you just try and deal with it the best you can there's lots that can be done and good success rates I'm currently on a list for the ablation apron 4/5 months wait , good luck with your journey through this try and keep positive although its quite hard too , cheers Paul


Welcome. You have just joined a new club! We are all different with AF but a lot of us exercise types find ways of handling it but still being able to exercise. I ran marathons and halfs for 25 years and found I had AF at 58. Does not occur during running but the next day. Also related to alcohol consumption so am now teetotal. Migrated to biking to give my knees a rest and been ling distance touring for the last 8 years. Now 66. Occaisionaly AF may affect my cycling but I then go at a slower rate and it often clears after half an hour. I avoid overdoing it up steep hills and avoid very rapid heart beats but still manage to climb hills in Pyrenees and Alps, just take my time. So far I have managed things without needing ablation or major meds. I take Losartan and warfarin.

1 like

Welcome in the club! AF affects people differently and you will see many different personal stories on this forum. I have been diagnosed with AF two years ago and had an ablation last November after which I had no more episodes of AF. But it is too early to say it got rid of it.

I did a bit of a literature search and fond that there is an emerging body of research with inconclusive results. Some studies find a link between endurance sports and occurrence of AF, some don't. I am intrigued by one study especially:

Atrial fibrillation in endurance athletes

Wilhelm, Matthias

EUROPEAN JOURNAL OF PREVENTIVE CARDIOLOGY Volume: 21 Issue: 8 Pages: 1040-1048 Published: AUG 2014

I quote an interesting paragraph:

In general population studies, the average prevalence of

paroxysmal or persistent AF is 0.5% in subjects aged

45–54 years, about 1% at 54–64 years, and 4% at 65–74

years.18 Pelliccia et al.19 reported a lower prevalence of

AF (0.2%) in young competitive athletes. AF

accounted for only 36% of all supraventricular arrhythmias

and was not associated with atrial remodelling.

In former elite athletes, who continued recreational

sports activities after the end of their competitive careers,

no AF could be demonstrated with Holter monitoring

at 15 years’ follow up, when the athletes had an

age of about 40 years.20

This indicates that if you were an elite athlete from young age your chances of getting AF are very low. They are much higher if you took up endurance sport as an adult. For example, one study found a substantially and significantly lower mortality among 786 participants of the Tour de France (from 1947-2012).


Yes AF is very different between different people but you will also find that for yourself it will vary quite considerably from day to day. Also people with paroxysmal AF have different affects and limitations to those who have persistent AF (some better, some worse). Some drugs don't affect some people and then the same ones affect others quite significantly.

I was in persistent AF, had an ablation and was in sinus rhythm for less than 72 hours and flipped back into persistent AF. However now I feel improved and can walk further since my ablation and I believe that is due to the fact that my SpO2 levels have improved significantly. Pre ablation 88 to 95% for 95% of the time. Post ablation (even though gone back into AF) 95% or greater for 100% of the time. Drugs have not altered. If I had picked up months ago about SpO2 levels that would have helped!!!

My suggestions would be get an Oximeter (useless for heartbeat), get a proper cuff BP monitor (some are specifically suitable for AF - eg AFA website) and consider getting an AliveCor to capture any events. Also AliveCor is most accurate for heartbeat.


Hi thanks for your reply.

I've heard a bit about AliveCor monitors, what are they and how do they work? I usually use a Garmin sports monitor to train by heart rate, these are usually reasonably accurate. You can download a detailed report of your activities on a pc. I've been using it to daily track my normal activities.

How does paroxysmal AF differ from persistent AF? ..forgive my lack of knowledge here!



A Garmin HR monitor will not show episodes of AF, it will just show HR. AliveCor records ECG data and thus enables you to see AF if and when it occurs.

Paroxysmal AF means it comes in episodes, persistent means you have it all the time.

Hope this helps


Thanks Grundy for replying.

I would add that when actually in AF most BP monitors do not accurately record heartbeat because they also count some of the AF interference in-between true pulses as pulses.


Hi, i recently posted here with a HR graph from "running" with my Polar HRM as, although i didn't feel any symptoms, the HR reading was not normal. If you do take a look i was purposely running slow due trying to keep my HR in check

When i'm not running i don't feel any AF, apart from the odd twinge or blip

I've been off meds for 12 months following a cardioversion

I'm hoping to get a stress test to determine what is going on when i'm running.

I too had "episodes" prior to getting full blown AF which was permanent for 5 months until the cardioversion. The episodes before that going back probably 10 years were just diagnosed as odd ectopic beats. I am 46 yrs old

I wouldn't class myself as an endurance athlete, however i have been running for 20+ years and have completed half marathons & sprint triathlons

For me i do believe that one or a combination of the following was the final trigger for my AF: sleep disturbance (young baby), hydration & caffeine

1 like

Hi and welcome.

That must have been a real pain in the posterior to get AF with your track record. If you've had AF during exercise you'll know at what BPM that is likely to happen for each sport. You can then try and keep around 10 BPM below that. You'll probably find that with some sports (usually non-weight bearing like the bike) you can carry on when you're in AF, albeit at decreased power output (that's when you've dropped off the pace in the pack). I used to do that but I came to the conclusion that my body had become accustomed to going into AF as it happened more frequently. After an enforced 12 month lay-off, I've just started the gym this month and I no longer go into AF during exercise even though I sometimes have a heart rate that would have previously kicked off AF.

Your low resting heart rate will make it difficult to prescribe medication to limit your AF. If you are prescribed dronedarone, post at any time and I'll set out the things to watch for if you are one of the very few people for whom it has an adverse effect (been there, done that).

The Atrial Fibrillation Association have an excellent selection of downloadable booklets that cover medication to questions to ask clinicians. You'll find that quite a few clinicians don't have an appreciation of AF and the effect it can have if you've been fit, or in your case, exceptionally fit.

Good luck and just treat this as zone 2 base building for the time being. It's not about selling the bike and hanging up the shoes, it's just a different training regime.


1 like

Thanks John, thats really sound advice. It's interesting that after you took an enforced break you're not getting the AF back when going back to exercise.

I regrettably stopped using my heart rate monitor during races, swapping it for watts & pace as a guide to my effort. I believe both running and cycling are when I have had the symptoms of AF. I tend to ride in a big ring and power round rather than spin cadence. The same for running.

I was prescribed Rivaroxaban after the Cardioversion nothing else and told to continue training, but at lower intensity.


It will be interesting to see if my body has un-learnt the tendency to go into exercise induced AF when I finish taking prednisolone (steroid) at the end of May. I've been taking it since July 2014 when I had inflammation of both lungs (SpO2 - 78%) caused by dronedarone and amiodarone. I don't take an anti-coagulant as I have a bleed risk. However, given the poor outlook at the third admission to hospital last year, I'm grateful to have a clear chest x-ray and be back in the gym thanks to the clinicians and nurses of the respiratory department at Southmead Hospital, Bristol. I just have to control my ego and those endorphins that whisper in my head "hammer it" when I'm in the gym.

I've always had a high heart rate during exercise and I knew I'd found the right GP, when she said that like me, she switched off the BPM alarm on her HRM when she ran! In my early 60's I still used 190 as my MHR and calculated zones using heart rate reserve. That was OK'd with a cardiologist. I hadn't been diagnosed then with AF but that came to the fore when my BPM was 180 on the start line of a 10k and, it would be in the range of 200 to 235 during hard efforts in or out of the gym. I was in denial until another GP referred me for a Bruce Protocol treadmill test.


Hi i was diagnosed with afib, thought it was asma, was gutted when i had e c g

doctor told me to go strait to A and E to get sorted, still got afib but on loads tablets.

Been sports man since i was 12 now 58, training 6days week weights cycling, never been ill in my life, never heard of afib before. Still go gym but don't do a

lot. should have stayed at home and watched T V. would be ok know.

Thats life. Dave


Similar thoughts occurred to me...

So what is recommended? I quote from the study above:

"What should we recommend to the followers of

Spiridon Louis? Should we encourage them to continue

high-intensity and prolonged endurance activities even

in their fifties? Although the aging endurance athlete

has an increased risk of developing atrial arrhythmias,

the benefits of regular exercise and an athletic lifestyle

far outweighs the negative consequences. In the initial

study of Karjalainen et al.,12 compared to controls, veteran

orienteers had a lower overall mortality despite

their higher risk of AF. However, male veteran athletes

especially should be aware of additional risk factors for

AF. Arterial hypertension is the most prevalent diagnosed

disease in athletes over 35 years old.29 Since athletes

are already likely to lead a healthy lifestyle, early

drug treatment for arterial hypertension, preferably

with an angiotensin II receptor blocker, is to be recommended.

35 Athletes with episodes of AF should reduce

training volume and intensity, and class I and III antiarrhythmic

drugs can be prescribed. Circumferential

pulmonary vein ablation is an option for athletes with

severe symptoms. A first-line approach can be discussed,

especially when the left atrium is not substantially


I was on Flecainide and Dilzem, then had an ablation. Now I am off the medication and nearly back to normal. Still talking Warfarin (will be reviewed soon) and my resting HR is slightly higher than before ablation.

In my case AF may have been induced by two important factors that are mentioned in the above study as well, Thyroid dysfunction and adrenalin rushes. I used to wake up sweating in the middle of the night. Now, after thyroidectomy I am much much calmer.


Thnaks for the bibliography! Just curious how you compiled it, using which search terms? I note the study I mentioned (by Wilhelm) was not included.

Did you read any of the sources?

Judging by the titles of the papers it seems obvious that the cardio research community is divided on the issue if endurance sport is conducive to AF


My consultant EP said about a number of the things that trigger / exacerbate AF. The one that was No 1 for me was adrenaline (often described in posts as an adrenaline junkie). I used to play a lot of competitive squash and hickey (a lot of indoor hockey) up to 33 when I was forced to stop because of a bad car smash. However my lifestyle was (up to last year) always working long hours, rushing about, cramming as much in as I could. Work was certainly an adrenaline producer with loads of important deadlines, etc.


Well this has been a very interesting discussion :)


My earlier post in this string mentioned that after a year away from the gym, my body seemed to have "unlearnt" the tendency to go into AF at 150 bpm during exercise. That still seems to be the case. I now do a steady 5km on a Concept 2 rowing machine at 106 - 120 watts at 146 - 150 bpm, then 20 minutes on an Ascent elliptical at 146 - 150 bpm with resistance increasing to level 20. No sign of AF. Another enforced break from the gym at the moment but hopefully I will be back by the end of June.

I'm keeping my fingers crossed that this could be a way to exercise without medical intervention. If it works for me, it might just work for others of us who exercise with AF.


You may also like...