AF Association
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Concerns while biking??

Ok , I'm 3 months into my cryo ablation and I'm noticing while biking that my HR drops significantly while under  some stress. We're talking like  going from an average HR of 145-155 to 55.I felt my pulse on my neck and it feels right and I'm not breathing harder. This has been happening for a few weeks . I sent a note to my ep  and he is not worried at this point. Should  I be concerned. This has never happened  to me before the ablation. Usually my hr while exercising has a pretty consistent range. Except when I had afib. Thanks

8 Replies

Hi Paul,

I don't know the answer to your question, but I am a biker myself (city bike), bike to work and back (around 8 miles a day.  What you are staying defies all logic.  The heart as you know, always increases it's activity when stress is placed on it, whether that be exercise or due to other stressful events.  I'm baffled to say the least.

Best Wishes



When I was in AF (136bpm) the nurse would regularly tell me that my pulse was normal (in the 60's). A senior nurse pointed out that only the ECG monitor would pick up the true rate during AF and demonstrated. I would hope that your AF has not returned so soon but remember they suggest it can be 6 months before they will know for sure and at least 3 months before the scars form sufficiently to block AF. Otherwise, I would feel fairly chuffed if I was only hitting my normal rate after a bike ride.


Before I was diagnosed I noticed that sometimes my HR would switch back and forth between two different rates as I cycled at a constant speed (and effort). It wasn't to that degree though, I'm talking about suddenly dropping from ~130 to about 115 (as measured on a Polar M52).

How are you measuring the 55bpm? Like Richmert, I find that it's easy to get the wrong HR during AF depending on how you check it. I've never seen an occasion when my M52 gives an incorrect reading, but infrared pulse oximetry gives a reading that is usually a third of the true rate, as does palpation.


I use a hr monitor strapped to my chest. It is possible that I have an issue with the belt. During these episodes I don't find my self gasping for breath like I did when in afib. My pulse rate feels normal for my rate of exertion at the time.  Me thinks it might be time to change the belt. If that doesn't work then change the watch . I'm trying to eliminate all the external possibilities.


You might be having brief arrhythmias, during which the HR monitor will pick up only the stronger beats.  Try measuring your pulse the old way - with your finger and a watch with a second hand.  Do it this way a few times at a higher level and the lower level.  That will tell you if your monitor has developed a case of the stupids.


HR monitors don't always work for arrhythmias. I was told that by an EP and he explained why. They MAY work, but it depends on the circumstances and your arrhythmia. In my case they do not work when in AF and I have three different makes and types. At one point I wore two of them and when I went into AF (which I could feel), the one went down and the other went up to 200 and stuck there!!! The EP said just feel your pulse, but more importantly take note of how you feel in yourself, or if you really want to hear what's going on, use a stethascope and listen (hard to do when you're cycling 😃🚲). 



Hi Paul,

I am a fellow long distance cyclist and recently had a cryo ablation.  Couple of points:

As noted, when in AFIB the heart rate measurement can be inaccurate. As an example, when I went into the  ER a few weeks before my ablation, they initially measured my HR at 60 even though I knew  that was inaccurate as my heart was jumping out of my chest.  A subsequent measurement when I was strapped to the EKG showed 165.  So, you can get these wild measurements when in AFIB, some of which are inaccurate. Surprised that your physician would ignore that possibility

Second, in any event, I would seriously consider slowing down your cycling pace.  If you are indeed averaging a HR of 150 at this relatively early stage of your recovery, you are putting way too much pressure on your heart.  I rode almost 13,000 miles during 2014 and 2015 with lots of climbing  and that may indeed have contributed to my AFIB. My heart rate averaged around 150 on most rides.   I started riding again two weeks ago but relatively short rides of 25 miles and I try to keep my average HR to about 125.  This obviously results in a slower pace but it's a starting point from which to build. 

Do check out your heart monitor to see if it is defective, but if not, insist in an appointment with your EP, get a 24 hour monitor to check EKG for AFIB and consider taking it a bit more slowly in the bike (believe me it's frustrating, but over time you will feel better). 

Good luck


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Jeff, thanks for the reply. Makes a lot of sense. I thought about the same thing concerning my EP. I am going to try positioning my monitor where it should be. I think I might of had it in the wrong area. If I still get the abnormal readings,I'll definitely call my EP


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