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Monday, November 05, 2007

Running won't save you from heart disease: How knowledge has advanced

As we have mentioned in our previous post, it has been a bad year for sudden death in athletes. Add to this two more cases that we did not mention - former basketball legend Dennis Johnson, who died suddenly after a coaching session in February, and Denver Bronco running back Damien Nash (24) who collapsed and died shortly after a charity basketball game, only two days after Johnson's death. In neither case was there any evidence of heart disease, and friends and family of both athletes (as is often the case) did not report anything abnormal about their loved ones prior to their sudden death.

These sudden deaths shake us to the core, for seeing someone so young and apparently healthy die suddenly just does not make sense to us. Over the last few days, in the wake of Ryan Shay's death, we've come across numerous discussion forums where this sentiment has been echoed.

Repeating the facts: Exercise is good and the risk is low

Just to repeat what we emphasized in our last post - regular exercise reduces the risk of disease, morbidity and death in ALL people, and so the beneficial effects of exercise far outweigh any risk of sudden death. People should therefore be encouraged to exercise regularly with the disclaimer that any signs or symptoms of heart problems should be taken seriously and examined. In addition, if you have a family history of heart disease or cardiovascular disease you should also be screened regularly. Remember - education, awareness and knowledge.

But the purpose of this post is not to state again what the actual risk of death is, but rather to examine the historical record of this topic. So we will delve back into the scientific literature and see what it can tell us, because at one time it was thought that marathon running protected you from heart disease!

Clarence de Mar: 1888 - 1958

As far back as 1961, Currens and White published a study in the New England Journal of Medicine on the autopsy results of Clarence de Mar. De Mar was something of a legend in American marathon running, winning Boston seven times and finishing third in the 1924 Paris Olympic Marathon. He had been a runner for over 50 years, and hence the interest in his physiology and his heart upon his death.

A heart that was immune to disease

The incredible, and novel, finding from this paper was that the diameter of de Mar's coronary arteries---the blood vessels that supply blood to the heart itself---appeared to be 2-3 times that of normal males. In addition there was almost no atherosclerotic plaque, which is the bad stuff that clogs your arteries.

This and other evidence led Dr. Tom Bassler to conclude in 1977 that marathon running would protect you from heart disease. Bassler examined the cause of death in marathon runners over the previous 10 years (circa 1967-77), and concluded that "there have been no reports of fatal, histologically proven, [CAD] deaths among 42K men". In fact, the title of his paper was, "Marathon running and immunity to atherosclerosis."

So that was that---10 years of marathon runner deaths, and not one case of coronary artery disease. Case open and shut. Or was it?

The Marathon: Physiological, Medical, Epidemiological, and Psychological Studies

This was the title of an incredible conference in 1977 held by the New York Academy of Sciences. The entire proceedings were published, and you might even be able to find an old copy out there on Amazon.com. It is a classic piece of scientific literature and one many runners (and athletes) might find very interesting.

The conference was a gathering of all the big names in Exercise Physiology, and included Dr. Tom Bassler presenting his hypothesis that marathon running produced immunity to coronary artery disease (CAD). However, also present was a young medical doctor from South Africa named Tim Noakes.

Dr. Noakes (now Professor Noakes) had gathered evidence from four cases; all were marathon runners, and all had died from CAD. So the hypothesis was rejected based on this evidence, and thankfully so. For while running marathons has been shown to benefit health, it does not make one immune from, well, quite honestly, anything!

Knowledge has evolved - even runners can suffer from CAD

Since then this topic has been studied at length, and the most recent position stand published jointly by the American College of Sports Medicine and the American Heart Association is available for free here. Its summary reads as follows:
  • "No sufficiently powered, randomized controlled studies have evaluated the contribution of exercise training to reducing CAD events. Nevertheless, a variety of epidemiological, basic scientific, and clinical evidence suggests that habitual physical activity decreases the risk of fatal and nonfatal CAD events and that the benefits of regular physical activity outweigh its risks. Consequently, physical activity should be encouraged for most individuals in accordance with the Centers for Disease Control and Prevention/ACSM recommendations for >30 minutes of moderateintensity physical activity such as brisk walking on most, preferably all, days of the week."
So again, we should all be encouraged to be physically active, be it running or cycling or tennis or walking, but at the same time we must realize that even though the effect of exercise on health is massive, it is still only one aspect of leading a healthy lifestyle.

American College of Sports Medicine; American Heart Association. Exercise and acute cardiovascular events: placing the risks into perspective. Medicine and Science in Sports and Exercise. 2007 May;39(5):886-97.

Bassler, T.J. 1977. Marathon running and immunity to atherosclerosis. Annals of the New York Academy of Sciences 301:579-592.

Currens JH and White PD. Half a century of running. Clinical, physiologic and autopsy findings in the case of Clarence DeMar ("Mr. Marathon"). N Engl J Med. 1961 Nov 16;265:988-93.

Noakes, T., L. Opie, W. Beck, J. McKechnie, A. Benchimol, and K. Desser. 1977. Coronary heart disease in marathon runners. Annals of the New York Academy of Sciences 301:593-619.


Anonymous said...

I have a little pet theory about why some people who are apparently very fit suffer from vascular disease.

I noticed that when I started training for Ironman triathlons, the significant increase in exercise meant I was hungry all the time. Instead of increasing my intake of healthy food, my junk food intake increased sharply.

I think many athletes allow their diets to be substandard and too high in saturated fats and empty calories because they can "get away with it" in terms of not gaining weight. Because they look healthy on the outside they don't consider the damage they are doing inside by making poor food choices.

Hung-Kwong Ng said...

There was a veteran marathoner who died from a clot in his coronary artery after the New York marathon.

Is there any data to show a protective anti-clotting effect of aspirin or NSAIDs taken during a marathon?

"Ellen Borakove, a spokeswoman for the New York City Medical Examiner’s Office, described his condition as acute thrombotic occlusion of the left anterior descending coronary artery because of arteriosclerotic heart disease. Dr. Jeffrey Moses, director of the Center for Interventional Vascular Therapy at the Columbia University Medical Center, presented with the exact cause of death, said that running the marathon “is a very likely explanation.” “When you exercise, your blood gets stickier,” he added. “So the likelihood of a clot forming during that period is higher. The clot probably formed during the marathon, and the average heart attack victim doesn’t call an ambulance or a hospital for about three hours.”

Anonymous said...

I'm not sure about any evidence showing a protective effect of NSAIDs during marathoning, but I'v read some research that NSAIDs taken in conjunction with exercise can lead to kidney damage and that doing so should be avoided.

Anonymous said...

For myself, Ive heard of at least one incident of an athlete suddenly dropping down dead. The anecdote goes on to say that minutes before dying, he was gulping down pints of water out of thirst.
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