Long-term endurance increases the risk of arrhythmia — New post up on theHeart.org

The idea that long-term endurance exercise increases the risk of arrhythmia should no longer be considered counterintuitive. The list of published studies confirming this association is long, and this week, it got a little longer.

In a study published in the European Heart Journal, researchers from Sweden report a cohort study of more than 52 000 cross-country skiers followed for decades. These were no ordinary weekend athletes; the analyzed group included finishers of the Vasaloppet, a grueling 90-km (55-mile) cross-country ski race. Reliable sources tell me that cross-country skiing over that distance is the Nordic equivalent of an Ironman or double marathon. Yikes.

The null hypothesis of the study held that both the number of races completed (exercise dosage) and finishing time (exercise intensity) associate with arrhythmia. (I would have bet my new mountain bike on that one.)

I hope you want to read more of my thoughts on this study.

Click here to read the full column on theHeart.org. (The column is under 800 words!)

JMM

P.S. You may have to register on theHeart.org. It’s free with an email address.

12 comments

  1. Having been guilty of all of the above, except for the Vasaloppet and an Ironman, I have spent the last seven years wishing a study like this wasn’t true. Now three ablations in my rearview mirror I have made a six month commitment to not have another a-fib. I have raced long and hard in the mountains of the west and Mexico on skis and on my feet. My first a-fib happened when I was 54 skiing uphill intensely at almost 13000ft, I was training for a forty mile ski race through the Elk Mountains I knew if I just went harder that weird heartbeat would stop. It did about six hours later. After the first two ablations I went right back to my hard pushing habits and got the same result, an episode every now and then sometimes three months apart. Some episodes were short others were thirty to forty hours resulting in more than five cardioversions. So, this go around I am practicing restraint, and I am sticking to my heart rate monitor and working with an exercise physiologist. (220 -your age is an outdated equation for establishing max heart rate. Any comments on this?) I am willing to avoid my old tendencies and now take the risk to get better, even if I have to miss those great hammer sessions.

  2. I’ve been a serious cyclist for (yikes) 42 years, including road and track racing, endurance events, tours, commuting, and weekend warrior stuff. Always thought more was better. At 42, when I started noticing a weird heartbeat and shorness of breath, I thought the reason was under-training, so I just trained harder. My now former PCP thought the palpitations, SOB, lightheadedness, leg weakness, and spikely BP were caused by a generalized anxiety disorder. Hmmmm…

    Like Paul Fuller, I’ve had three ablations and after the first two, I used to work-out really hard. Being an engineer, I was trying to test the effectiveness of the procedures. Since the third an;ablation 20 months ago, I’ve really backed-off on my training and have noticed no AF and far fewer PACs/PVCs. In the next few months, I hope to increase my cycling miles and even acquired a sweet new ride as inspiration. Will keep the Swedish study results in mind to contain my irrational exuberance.

  3. Dr John
    I am not looking to you for medical care, but for basic understanding.
    The summary below was written re: the recent studies providing evidence that Afib may be associated with neuro-degeneration /dementia of various kinds. It will serve to give my background for the question following:

    >>>>>>>>>FWIW: Age: 77. (1936) Currently being treated for permanent Lone Afib RPR 80-85 bpm. Prior RPR had been 55-60 for many years. Only med is Warfarin. Also successfully using CPAP for Apnea. Afib turned permanent about a year ago, following preceding 5 years where brief periods of arrhythmia and apnea remained undetected. Apnea/Hypopnea were diagnosed, soon after Afib confirmed. Tikosyn trial/ and 2 cardioversions failed at one week duration. Discontinued Tikosyn. Following approx 5 months experienced (new)excessive day time sleepiness, forgetfulness, poor access to normal vocabulary. This has improved as I became accustomed to CPAP use. Have also begun an un-supervised trial of magnesium L-threonate, which is claimed to penetrate blood brain barrier. My current feeling is that (for whatever reason), mental performance is slowly, but steadily improving. (My wife endorses this observation ;-). Will consider FIRM ablation at a future date if and when effectiveness on permanent AFIB is confirmed. >>>>>>>>>>

    Question:
    My EP has given me good conventional background on what is going on with my Afib. My CHAD score is ‘1’ for ‘old age’.
    I have not in many years done any thing that could be considered serious athletic training, say for cycling or skiing, or marathon. BUT: I would like to know if you (or anyone else in the field) may have given any consideration to the following possibility.:
    That the exercise ‘effect’ (or damage?) which may link endurance exercise with Afib, or perhaps even Afib with Apnea, Alzheimer’s or Parkinson’s, could be accumulated, not necessarily continuously, but over many decades.
    I earned a low resting pulse rate in my teens and twenties. rode an engineering desk for the next 30 yrs, finally managing 20 miles per week between ages 50 and 60. (I have no other degen. diseases, but I have been treated for familial hypothyroidism fo most of my adult life.)

    I seriously appreciate your writings @ the Heart .Org., especially knowing that someone out there is willing to show show some of what it takes mentally, emotionally, and physically, to treat a patient. Can’t thank you enough for what you do..
    Mike Vidler

  4. THANKS for your post Dr. John. To me it makes perfect sense that extreme exercise over time may predispose even ultra-fit athletes to develop cardiac arrhythmias (esp. AFib). Good information to have prior to my upcoming Primary Care Arrhythmia Update that I’ll be presenting. I also like your message that the above applies to extreme exercise – so the message to those listening is that extreme training has a potential longterm “cost”. THANKS for posting!

    P.S. Interesting comments from your readers!

  5. My former EP is still using 220 minus your age for max heart rate, and 85% of that as being a good level to sustain for aerobic training. Has that thinking changed at all? How do we know until we over-do and then with the benefit of 20/20 hindsight think maybe that last climb was a bad idea?

    1. Allison – As a competing biker and cardiologist, Dr. John will give you a more scientific and experiential answer than mine. My thoughts (if I understand Dr. John’s points correctly) – is that the type of “inflammation” that predisposes some athletes to developing certain cardiac arrhythmias is a longterm evolution following ultra-intense workouts – be this for marathons, biathlons/triathlons, extreme sports, etc. It is not the type of thing likely to happen from “one last climb or ride” unless one is pushing oneself beyond reasonable limit. Good nutrition – adequate rest & sleep between events probably go a long way toward reducing arrhythmia risk. All that said – there is indeed a fine line for those athletes desiring to attain a certain level of excellence that requires persistent intense training. The point of these recent findings reported by Dr. John is that such longterm intense training may come at a “cost” (ie, increased risk of ultimately developing arrhythmias). For the rest of us who are not competing at such a high level – We are now more aware that pushing oneself “beyond normal limits” is not necessarily benign in the longterm …

      As to “220 minus Age” – I used this formula for years while doing ETT (Exercise Treadmill Testing) in the office. It gives you a “ballpark” for what maximal heart rate is likely to be – albeit subject to much variation. Rate slowing drugs may clearly affect the number. Some individuals “don’t read the textbook” – and develop heart rates faster or slower than this number. Whether one strives to attain 85% of max predicted heart rate – or lower levels (70-75%) might depend on the intensity of exercise that you are hoping to achieve and maintain (endurance vs sprint-type training). That said – the best way (in my experience) to truly figure out the optimal training rate range for any given patient is by doing an ETT in the office and seeing what heart rate corresponds to what level of activity for THAT particular individual. The clinician doing the ETT can then provide an “exercise presciption” with heart rate limits. That said – I always used a modified (customized) Balke protocol whereby the individual rated level of activity that I could then correlate to performance on the treadmill – allowing me to optimize exercise prescription specific for that individual (who would exercise until a subjective 7 or 8/10 score that I correlated to optimal activity range while doing the ETT – rather than asking the patient to worry about taking their pulse during full activity).

  6. As someone who has been a long term exerciser both cycling and a marathoner as well as someone with PVCs I find these articles interesting. Once again I think the “extreme” exercise needs to be redefined because that definition is far too vague. My exercise patterns over the years are quite sedate to an olympian but quite extreme to a couch potato. And more importantly our cardio systems and bodies are quite unique so what taxes my cardio may be run of the mill to someone finishing along side of me. I am curious if anyone doing these test are looking at electrolyte imbalances or heart muscle sizing or overall blood chemistry to see if there is any correlation besides just exercise. Lastly I would love to know if these issues resolved once exercising at a high level was stopped.

  7. As an AFIB patient, I am working on getting back in the saddle, as it were, with my exercise program. While I am not an “extreme” athlete by any measure, I was trying to get back to pre ablation level of fitness/endurance capability and am struggling. Are there any studies/guidelines etc for a person like myself to use as a guideline. Am 60 and 18 months out from ablation procedure and event free so far.

    1. Mike – As a former primary care provider who did and supervised treadmill testing for all of our residents and other faculty for many years – my advice given that you are of a “certain age” would be to contact either your primary care clinician (if they are comfortable in this area) or your cardiologist. I would not think exercise prescription for a patient such as yourself would be something I (or other clinician) would be comfortable doing via internet without touching base in person. Dr. John may have additional insight to your question.

      1. Thanks. My Cardiologist put no restrictions on me. Still a bit hesitant and was looking for any data. I appreciate the response.

  8. Hopefully the researchers can use this cohart data to study what other factor may contribute to Afib like alcohol, stress, diet…
    That would be where the real value might be.

    1. Extremes of exercise can themselves be considered stresses, as can just about any excursion from our norms. (eg temperature, nutrients, etc) Such stresses can produce metabolic or perhaps epigenetic responses.
      I think the principle of Hormesis may one day help to give us answers.
      Meanwhile, please take a look at the work of these biologists:
      *Best in small doses*
      ‘Sometimes a smidgen of toxin can be just what the doctor ordered’,
      say biologists Mark Mattson and Edward Calabrese.

      http://www.grc.nia.nih.gov/branches/lns/BestinSmallDoses.pdf

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