Ironman and Heart Health: My Take on Things

For those of you who don’t already know him, let me introduce you to Dr. John Mandrola. You can read his musings at his Dr. John M Blog and follow along with his Twitter feed. John is a cardiologist in Lexington, Kentucky, who specializes in electrophysiology; he takes care of patients who have all sorts of abnormal heart rhythms, offering diagnosis and the entire spectrum of treatments available to these patients. He’s also a competitive cyclist and, at some point, was a triathlete, as well.
I particularly enjoy reading his Cycling Wednesday blog posts that are usually devoted to the “intersection” of medicine and cycling. These posts would be recommended reading for most athletes regardless of their sport. What I enjoy most about these blog posts are John’s skill at human observation, his ability and willingness to describe our follies (both physicians’ and athletes’), and his seeming general skepticism about many things. We often see things the same way.
The week before last, Dr. John wrote a blog piece entitled, “Is the Ironman triathlon heart-healthy?” Needless to say, this caught my eye. And, judging from the many comments I received afterwards, it caught the eye of a good many other triathletes as well. I also saw that there was a lively discussion on the Slowtwitch forum, with many triathletes weighing in on Dr. John’s thoughts and offering some personal accounts of various heart ailments as well. I also see that Dr. John received many replies and comments at his blog and felt obliged to issue “An Iron response….” at his blog a couple days after the original post.
Dr. John offered some important thoughts about endurance training and racing and their impact on heart health. These issues are important. His blog piece contained both opinion and fact. And, while it might be easy for me (as another medical professional) to see the difference, I can tell that many readers weren’t able to make that distinction. They got upset about some of the opinions and lost track of the facts. I thought I’d take a moment to separate out the opinions and facts–at least, as I see them–so that our readers might be in the best possible position to draw their own conclusions.
1. Ironman is the pinnacle of triathlon. No doubt, some people hold this opinion, but I’ll bet that many triathletes don’t. Olympic-distance (draft legal) racing is probably also a contender for being the pinnacle of our sport in many people’s eyes.
The participation rate for Ironman distance triathlon is relatively small. With about 25 Ironman-branded races worldwide each year and some number of other races of iron distance, the number of participants each year worldwide is probably less than 75,000. To put that into perspective, USA Triathlon recently reported that in the United States alone, there were 2.3 million triathlon participants in 2010. I’ve raced in 6 Ironman races over the past few years and each of those races held a pre-race dinner a couple nights before the race. At each of those dinners, 40-50% of the crowd stood up when the first-timers were introduced. With that statistic, it’s obvious that many Ironman participants are “one-and-done.”
2. Ironman triathlon….I don’t get it. Sure. Not everybody “gets it.” I could say the same for golf or tennis. To each, his own.
3. Heart healthier ideas: marathon or shorter running race, bicycle racing, shorter-than-Ironman triathlon. There is ample evidence that aerobic exercise produces long-lasting health benefits, including a longer life-expectancy. There has been speculation that, beyond some amount or intensity of exercise (or a combination of both), there might be some harm, including injury to the heart. I’m not aware of any credible studies, though, that address this issue in terms of the relative safety of 1 endurance sport over another….or race competition of 1 distance over another. In my view, it’s hard to imagine that half marathoners are somehow “heart healthier” than marathoners….or that half Ironman triathletes are somehow “heart healthier” than full Ironman triathletes. This issue about some threshold for harm remains unstudied….and therefore unsettled.
4. Can’t imagine riding for 5 hours continuously at 200 Watts. Obviously opinion. For me, it would be nearly 6 hours at 180 Watts. But BTW, I’m always willing to stop for a cookie break….on a training day OR at the race!
5. Long-term, low-intensity, ultra-endurance exercise (slogging, not racing) isn’t heart-healthy. Opinion. We know that long-term, low-intensity exercise IS heart-healthy. I’m not sure what qualifies for “ultra-endurance” and I’m not sure that “slogging” vs. “racing” makes a difference for the heart. Again, this issue simply hasn’t been studied.
6. The occurrence of fatalities during Ironman triathlong might entice others to participate. Perhaps. I suppose anything is possible, but I haven’t encountered that motivation. It’s important to remember that the small number of fatalities at triathlon races have occurred in races of all distances and the victims have spanned a large age range and ability level–from novice to veteran triathlete. In truth, most triathlon race fatalities have occurred in shorter-than-Ironman races.
1. Ironman triathletes are focused. True. Regardless of the particular hobby, anybody who spends 10-20 hours per week doing something is focused.
2. Daily exercise is good. Irrefutable fact.
3. Athletes are more likely to die of sudden cardiac death (SCD) during exercise (or competition) than non-athletes (who don’t exercise). Fact. SCD is not related solely to triathlon, though. A recent study of SCD in the general adult population showed that this occurs in (decreasing order of incidence) cycling, jogging, soccer, hiking, swimming, basketball, rugby, tennis, diving, judo, handball, alpine skiing, table tennis, and body building, among other sports. Cycling accounted for almost one third of the SCD events. Although most of the triathlon race-related deaths have occurred during the swim portion of the race, in the general population SCD while swimming accounts for only about 4% of the total number of episodes. On balance, though, the health benefits of exercise appear to far outweigh the small risk of SCD.
4. Endurance athletes are more likely than non-athletes to develop atrial arrhythmias. Fact. There is overwhelming evidence for this. Many references are included in Dr. John’s second blog post. This issue hasn’t been well studied in triathletes, but there’s no reason to think that triathletes are immune. The influences of exercise duration and/or intensity on the development of these arrhythmias need further study.
5. Scarring in the heart has been found in long-term endurance athletes (and laboratory rats). True. I wrote about the recent studies in a column at Endurance Corner. It’s important to remember, though, that scarring was only found in veterans of many, many marathons….and the clinical significance (if any) has not yet been determined. For now, there is no evidence that the scarring led to a shorter life or was associated with other heart problems in these runners, but these observations merit further study.
6. Heart damage can be detected after an endurance race. True. Studies have shown elevated levels of cardiac enzymes (indicating heart cell damage) in the bloodstream and altered (diminished) heart function by echocardiogram in athletes immediately after running and triathlon events. These abnormalities have not been shown to persist and so their significance (if any) is not clear. Some authorities have speculated that repeated episodes may be harmful.
1. Sudden cardiac death (SCD) is “not uncommon” during triathlons. This simply isn’t true. SCD is actually a rare event at triathlons. There is a single report on this issue that showed SCD to occur at a rate of approximately 1 per 65,000 participants. USA Triathlon is convening a Taskforce to examine this issue in further detail and I’m certain that additional information may be reported in the coming months. To give this issue some context, it was reported earlier this year that the rate of SCD among NCAA athletes (in all sports) was approximately 1 per 45,000 athletes per year.
Let me finish by saying that Dr. John’s list of 7 suggested activities at the end of his first blog piece are great ideas. I need to work on #2, #3, and #6. I’ll report back.
1. Swim a fast and smooth 400-yard individual medley (100 yards each of the butterfly, back, breast, and freestyle strokes
2. Ride a criterium bicycle race
3. Train to knock 1 minute off your best 10 km run time
4. Complete an Olympic-distance triathlon
5. Try touching your toes without bending at the knees
6. Write a blog without a grammatical error
7. Sit still long enough to read a book
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  1. says

    Super post. Thanks for clarifying a number of areas of potential confusion. Living in a state (KY) where the rate of morbid obesity is staggering, I’d hate for my fellow citizens to take from Dr. John’s post that exercise is more dangerous than sitting on the couch. After all, while it is sad that someone died during the Louisville Ironman, how many other Kentuckians died on that same day from heart attacks while doing something (or nothing) else?

  2. says

    Hi Lawrence,
    I was just writing a piece for my blog on an article by John Mandrola that was essentially castigating us Ironman distance triathletes. It was clear that he ‘just didn’t get it,’ and there were no comments. Consequently I made my thoughts known. As I was finishing of my post for tomorrow based on my response, I did little more research on the topic and came across this piece by you, which nicely wraps up my thoughts and adds a great deal of useful information. Thanks for doing all the work for me. It is much appreciated. I will send my readers in your direction at the end of my post (comes out tomorrow, at 6:00 am).
    -k @FitOldDog

  3. says

    Dr Creswell –

    Thank you for this blog and info regarding full Ironman events. Soon after completing a full Ironman I had a heart attack which concluded with a triple bypass. Im 41 years old and was in excellent shape which startled doctors and everyone in my life. I definately think I would have had a heart attack if I never competed because of my cholesterol and general hypertension. I do believe competing in this event brought the heart attack on much faster than if I’d only competed in shorter distance events.

  4. says


    I hope you’re making a good recovery.

    Yes, heart attack can sometimes be provoked by exercise….even sometimes very “easy” exercise.

    Hopefully you’re able to focus on the modifiable risk factors for coronary artery disease: not smoking, keeping a normal wight, blood pressure, etc.


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