There has been a lot of conversation this week about an article that appeared in the Wall Street Journal (WSJ) in its November 27th U.S. print edition, entitled "One Running Shoe in the Grave." The online version carries the additional subtitle, "New Studies on Older Endurance Athletes Suggest the Fittest Reap Few Health Benefits." The article by Kevin Helliker offers information and comment about an editorial by Mid America Heart Institute cardiologist, James O'Keefe, MD, entitled, "Run for your life ... at a comfortable speed and not too far" that was published online last week by the British medical journal, Heart.
Obviously the headlines from the WSJ article and the Heart editorial are sensational. The headlines were designed to attract readers. And they did. What editor or publisher wouldn't want that, I suppose? The British newspaper, Globe and Mail ran with the headline, "Running can shorten your life." Really?
There have been a bunch of opinion pieces this past week about the WSJ article, Dr. O'Keefe's editorial, and the general topic of endurance sport and cardiac health. Here are some links to thoughtful pieces that are good reading:
Chris Carmichael, CEO/Head Coach at Carmichael Training Systems, shares a blog piece about cycling, running, and the importance of fitness.
John Mandrola, MD, cardiologist/electrophysiologist and cyclist, reviews the issue in his Cycling Wednesday blog post, "I Told You So...."
Alex Hutchinson shares a review of the issue at the online version of Runners World, taking issue with many of the assertions by the WSJ and Dr. O'Keefe.
Michel Accad shares a blog piece, entitled, "O'Keefe on exercise: prescient or premature?". There's a video clip of an 18-min. TED talk by Dr. O'Keefe about the potential dangers of exercise. It's worth watching. And Accad's comments are worth considering.
You might finish reading my blog entry here and then return to read the others' takes on this issue. There's an array of opinion.
A Review Article
The conversation actually began in June of this year when Dr. O'Keefe and his colleages in Kansas City authored a review article for the Mayo Clinic Proceedings, entitled "Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise." This is an excellent article because, in 8 short pages (excluding the references), it gathers almost everything important that scientists know about the issue of long-term adverse consequences of endurance sport. There is also a long list of scientific references for those who want to do additional reading. If you're an endurance athlete, I would encourage you to read the article.
Here's my condensed list of facts that are presented:
1. The opening sentence reads, "regular exercise is one of the cornerstones of therapeutic lifestyle changes for producing optimal cardiovascular (CV) and overall health." True. The health benefits of exercise are many and undeniable.
2. A small number of endurance athletes will die while exercising from "suden cardiac death" (SCD)--a suden, fatal arrhythmia. These are rare events but can occur at any age and with any form of sport. The cause is most often an underlying, unrecognized heart problem.
3. Over the long term, endurance athletes may develop a condition known broadly as "athlete's heart," a collection of structural adaptations to chronic exercise. The authors speculate that these changes may not always be healthy. At present, though, there is scant evidence in animals or humans to help us understand this issue completely.
4. Immediately after endurance events, athletes have been found to have release of heart enzymes (troponin) into the bloodstream that might suggest injury to the heart. Moreover, studies have shown some athletes to have a decrement in heart function immediately after such events. The accumulated body of evidence suggests that these changes are short-lived and the long-term consequences of repeated episodes remain unknown.
5. There is an irrefutable relationship between long-term endurance exercise--in many sports studied--and atrial arrhythmias such as atrial fibrillation. The exact mechanism is unknown, but it is reasonable to speculate that there are structural changes in the atria (the upper chambers of the heart) that lead to problems with electrical activity in those chambers.
6. In a small number of long-term runners, abnormal fibrosis (scarring) has been identified in the heart's walls using a magnetic resonance imaging (MRI) technique known as late gadolinium enhancement (LGE). The origin of these findings and the significance of these findings is unknown, but such findings are typical after heart injury that occurs with myocardial infarction (MI), or "heart attack," as it is commonly known.
Those are the important facts. The authors share their concern about the possibility that too much exercise may be harmful and correctly note that all of these findings should stimulate our interest in better understanding the long-term consequences of endurance sport. That's certainly reasonable.
The New O'Keefe Editorial
In their new editorial in Heart, Dr. O'Keefe and his colleague, Carl J. Lavie, MD, extend their earlier conversation. Unfortunately this article is only available online for subscribers of the journal. They introduce the editorial with the ancient 490 BC story of Phidippides, the runner who made his way from Marathon, Greece to Athens to share news of the Greek victory in the Greco-Persian War, only to die suddenly on his arrival at the Acropolis. But the editorial doesn't focus on the issue of SCD in endurance athletes, it deals with the broader issue of potential cardiac harm. This editorial appears to be a response to critics of their conclusions in the earlier review article and the authors single out Editor-at-Large for Runner's World Magazine, Amby Burfoot, as one of those critics.
I take odds with virtually all of O'Keefe and Lavine's assertions in the editorial.
The first major study mentioned in the editorial is a large prospective study of 416,000 individuals that was reported last year in the medical journal, Lancet. In Figure 1 of the editorial, the authors display the reduction in all-cause mortality for individuals grouped according to the amount of their exercise: one group with "vigorous" exercise and a second group with "light to moderate" exercise. It is VERY important to note that the reduction in mortality occured for ALL amounts of exercise included in the observations. With "vigorous" activity, individuals still were continuing to accrue additional benefit in reduction in mortality at the 45-min per day point at which observations were censored. And moreover, those individuals enjoyed GREATER reduction in mortality than the group who did "light to moderate" exercise.
The authors then speculate about the cause of death last year of Micah True at age 58, the ultra-distance runner who once served as the basis for the popular running novel, Born to Run. Here at the blog I've written previously about the details surrounding his death. O'Keefe and Lavie note that at autopsy, True was found to have an enlarged heart with "focal areas of interstitial chronic inflammatory infiltrate." The medical examiner noted that True had "cardiomyopathy" of an unclassified origin that resulted in a fatal arrhythmia as he was running in the desert of New Mexico. O'Keefe and Lavie speculate that True had some sort of "Phidippides cardiomyopathy." It sounds sensational to evoke Phidippides, but I'm not sure that most authorities would even recognize that term or that condition. From my standpoint, even absent the most classic pathological findings, the most likely explanation for True's death is Chagas disease (caused by parasitic infection common in the desert Mexican region that True inhabited) that produced the structural changes in his heart and lead to his fatal arrhythmia.
Lastly, the editorial shares information presented in abstract form at recent medical meetings. It's important to keep in mind that a great deal of scientific exchange happens at medical meetings, but there is very little scrutiny of what's presented. Essentially, if you're invitied to speak at a meeting you can say what you want--whether it's scientifically correct or not. Attendees must use their own judgment about the scientific merit. There's a much higher standard when it comes to publishing results in a medical journal, where a manuscript is reviewed by one's peers and a medical journal's editors to be certain there's scientific merit to the information that will be presented. Neither of the cited presentations or abstracts have yet made their way to a medical journal yet. And they might never, for all we know. Again, the bar for scientific accuracy is generally LOW at medical meetings and we should keep that in mind.
In the first study cited by the editorialists, Duck-chul Lee and colleages at the University of South Carolina and at Ochsner Health System in New Orleans reported in June at a meeting of the American College of Sports Medicine on a group of 52,656 adults aged 20-100 years who had a medical examination during 1971-2002 as part of the Aerobics Center Longitudinal Study. They found that with average follow-up of 15 years, runners enjoyed a 19% lower risk of all-cause mortality than non-runners. That's important, but certainly not a new observation. That observation has been made in countless previous studies. O'Keefe and Lavie make note of the relationship between the AMOUNT of running and the reduction in mortality and show a Figure 4 bar graph that summarizes a hazard ratio of all-cause mortality for groups according to the amount of running. Just glancing at the graph, the bars show lower hazard ratios for individuals with moderate (10-20 miles) amounts of running per week and higher hazard ratios for those who ran more. But although they make much of the "U" shape of that bar graph suggesting a "sweet spot" for the amount of beneficial running, they don't mention at all that the 95% confidence intervals for ALL of the bars are overlapping. That is, from a statistical standpoint, the original scientists FAILED to find a relationship between the amount of running and the hazard ratio for mortality. A reputable medical journal would preclude any conclusion other than: "there is no association between the amount of running and the hazard ratio for mortality."
In the second study cited by the editorialists, Dr. Peter Schnor, the chief cardiologist of the Copenhagen Heart Study made a presentation at the May 2012 EuroPRevent meeting in Dublin, entitled, "Assessing prognosis: a glimpse of the future. Jogging healthy or hazard?" The Copenhagen Heart Study is a long-standing longitudinal study of 20,000 Danes since 1976. Not surprisingly, Dr. Schnor reported that with follow-up for as long as 35 years, the risk of death among male joggers was 44% lower than for non-jogging males; the risk of death among female joggers was also 44% lower than for non-jogging females; male joggers lived 6.2 years longer than non-jogging males; and female joggers lived 5.6 years longer than non-jogging females. Those are BIG, IMPORTANT numbers! Take note. Although the details have not (yet) been published, Schnor has shared with reporters that the greatest benefits were derived by those who did from 1 to 2.5 hours of jogging per week, over 2 to 3 sessions. That may be true, but we must also keep in mind that Dr. Schnor has previously reported in the February 2012 issue of the European Journal of Preventive Cardiology that cyclists from that same Copenhagen Heart Study enjoyed the greatest health benefits if they cycled HARD and FAST! Indeed, they reported that "Men with fast intensity cycling survived 5.3 years longer, and men with average intensity 2.9 years longer than men with slow cycling intensity." I refuse to believe that the human heart "knows" what form of endurance sport an athlete is doing, so we're left to try to reconcile the discrepant findings for runners and for cyclists. And absent more detailed, published information, I'm not sure how we can do that.
Some Final Thoughts
We need to keep an open mind as we continue to learn about the long-term cardiac consequences of endurance sport. The issue of whether there can be "too much" exercise is an important one. I think we'd all have to agree that if you're exercising for more than 7-10 hours per week, you're doing so because of some motivation other than simply your health. Given the indisputable health benefits of exercise, though, I'd hate to see anybody choose a sedentary path because of concerns about possible adverse health consequences. Runners should not return to the couch.
Lastly, I'd caution against sensationalism. And that's what this entire week's discussions have screamed. Physicians and scientists should use a voice of reason and editors should be sensitive to the issue of over-reaching when it comes to publication in the popular press. We don't need headlines. We need science.
