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Saturday, July 21, 2007

Sudden death in runners - isn't exercise meant to protect the heart?

UPDATE: In yesterday's US Olympic Trials, elite runner Ryan Shay collapsed and died at the 5-mile mark. No autopsy yet, but we have looked at this sad event in a series of posts you can read here. We look at Sudden Cardiac Death, and some of the more common causes in more detail. We also devote a post to the career and performances of Ryan Shay.

Disclaimer: I joked in our previous post that we would need a disclaimer, and sure enough, we did! This post is updated from the one that was posted yesterday, in response to a comments regarding terminology and statistics. So before we begin, we clarify some definitions:
A Heart Attack
is caused by a circulation or plumbing problem in the heart,;while Sudden Cardiac Arrest is caused by an electrical problem in the heart.

In our last post, we used the term heart attack, and were informed that this was incorrect, and should have been cardiac arrest - we disagree with the 'incorrect' part, though we acknowledge that sudden death during exercise can have electrical explanations, and so perhaps 'incomplete' would have been more appropriate! Ou
r focus in the post is primarily on the circulatory causes which we believe are still more prevalent, according to literature on runners (see the Jim Fixx section). In this post, then, we speak of heart attacks. I'm sure the 'purists' will shudder, but this is not a peer-reviewed journal article, so we have to take certain liberties or we would end up writing a thesis that no one would read - one of the prolems with science, sometimes. Perhaps in the future, we'll do a separate post on electrical disturbances...

Jim Fixx, Alberto Salazar, Alem Techale, 2 Comrades runners this year.
aps you recognize some of these names, others not. But they all have two things in common. First, they suffered heart attacks/sudden cardiac arrests (heart attack from now on!). Second, they are athletes (different levels, sure, but athletes nonetheless), and their heart attacks happened while they were running.

Most recently (2 weeks or so ago), Alberto Salazar, winner of the 1994 Comrades Marathon, winner of the 1982 Boston Marathon, three New York Marathons, and former world record holder, suffered a heart attack aged 48 during a coaching session. You can read more about this story here. Salazar recovered, the others were not so lucky. Famously, Jim Fixx, who wrote the book The Complete Book of Running, died at the age of 52 during a training run in 1984. Alem Techale, fiancé of Kenenisa Bekela, collapsed during a training run in 2005.

These events tend to be emotive topics, because they shatter the perception that the fit among us are immune to this problem – the world record holder, a man who runs 50 miles a week, having a heart attack! Surely not? So what we at The Science of Sport thought we would do is take a look at the physiology and medicine of sudden death and heart problems during running. This is of course a very complex topic – this post should come with a disclaimer – it can’t possibly cover all the options, but it does present the most common explanations for what we all read about with shock when the ‘ambassadors’ of healthy living are struck down by what we see as a disease of the unit.

The history of our perceptions

In the 1970’s, the American Medical Joggers Association (yes, it’s a real name!) published a report in which they claimed that not a single marathon runner had died due to a disease called coronary artery disease – in this disease, the arteries that supply blood to the heart become narrowed by cholesterol deposits inside them, and the heart’s blood supply can be restricted. It’s a common cause of heart attacks.

The conclusion made by the AMJA, led by a scientist named Bassler, was that marathon running provided immunity against coronary artery disease and heart attacks. This became known as Bassler’s hypothesis, and it contributed to the “running boom” of the 1970’s.

However, by the mid-1980’s, cracks began appearing in the façade. Two deaths during training were reported by scientists from UCT, and so the “protection” theory was questioned. In 1984, data were published showing that 75% of athletes who died during exercise had signs of severe cardiac disease, effectively disproving the Bassler hypothesis.

That’s not to say, of course, that regular exercise is not beneficial, because it is. There is a wealth of research that suggests that regular exercise improves heart health. But the net result of all these studies was that while a marathon runner is less likely to develop coronary artery disease, they are not immune.

How often does it happen?

So with that in mind, how often does a heart attack during exercise happen? Without wishing into going into too much detail, studies have looked into this and found that the risk of sudden cardiac death is incredibly low, much lower than it is for the “normal” population. For example, one study in Rhode Island found that there is one death per 7620 runners PER YEAR. That is incredibly small – remember, a “normal”, non-running group of 7620 people has a much higher chance that at least one person will have a heart event per year. Another study found that the risk of death in a group of runners was about 1 in 50 000, or 1/100th that of a non-running population. Those are odds I would certainly want in my favour!

So what MIGHT HAVE happened to Salazar?

It’s impossible to answer this question of course, his doctors would probably know, I’m just guessing. Also, we don’t want to write a thesis here, so we take some liberties with the full story, but we will put out a few possibilities (remember our disclaimer...?)

Studies from the 1980's and 1990's have found that virtually all the runners who die suddenly during exercise are suffering from some sort of serious heart disease before their fatal heart attack. There are probably about 30 possibilities, but we’ll focus on one or two.

Coronary artery disease (CAD)

The most common one by far is coronary artery disease, or CAD, which we mentioned earlier. This is where the blood vessels supplying the heart become ‘choked’ due to cholesterol plaques that form over the years. This is the main cause of death in runners older than 35 – the plaques take time to form and eventually completely block off the blood supply to the heart. The heart, of course, can’t function without the blood and the muscle dies as a result. It’s quite logical to see how exercise, if not controlled, will contribute to a heart attack, because the demand from blood and oxygen by the heart is greatly increased, and there’s also more chance of a plaque being dislodged and blocking the vessel completely. This is what happened to Jim Fixx, with the autopsy showing that one coronary artery had 95% blockage, a second 85%, and a third 50%.

This, by the way, is also the reason why people with high blood pressure or CAD should not do heavy weight training – the blood pressure rises drastically during weight training and this can cause the plaque to break off, causing a heart attack. So people with high blood pressure or CAD are better off doing cardiovascular type training, where the blood pressure rises far less.

Cardiac abnormalities

In people who are younger than 35, the cause of death is more likely to be what is called a congenital cardiac abnormality. There are loads of these, and then include something called hypertrophic cardiomyopathy (apologies for all the medical terms and lengthy words). This is basically a disease where the heart muscle grows in size (that’s what Hypertrophy means) to the point where the blood supply is not sufficient to meet the demand, and the overgrowth of the muscle interferes with the ability of the heart to contract and relax. In other words, a large muscle needs greater blood supply and this can’t be met. There are reports, for example, of cyclists who increase the size of their hearts through training and eventually reach the point where they cannot supply enough blood to the muscle. So in some people, the size of the heart muscle is simply too large to supply blood to, and the muscle becomes diseased as a result (this is the cardiomyopathy part).

In young people, there is also something called familial hypercholesterolemia – as the name might suggest (by the time you finish re-reading it!), this is a condition where you can inherit (familial = family) high cholesterol levels. So when a young athlete dies, it’s possible that they have the coronary arteries of a much older person, purely as a result of their genes. This is of course also a major factor for older runners – Jim Fixx’s father suffered from two heart attacks, one aged 35 and the second (fatal) one at 42. So his problems were certainly related to heredity.

There are of course many other possibilities, include abnormalities in the arteries, and diseases with exotic-sounding names like dysplasia, Marfan’s Syndrome, and myocarditis. Then of course,there are the electrical disturbances, including arrythmias and channelopathies. But this post is technical enough without details on these. So we'll settle on CAD and hypertropy. If there are any specific questions, we’d be happy to attempt to respond, but we’ll leave the technical stuff there!

But before we move onto the practical information and message, it’s worth also pointing out that heart attacks can also be caused by exercising with a viral infection. This can cause a virus to infect the heart muscle (myocarditis) or the pericardium (a membrane around the heart – pericarditis). When this happens, the athlete can die even though they are otherwise healthy. So if you have flu symptoms, this is the critical reason why exercise is not recommended. I’ve heard reports that a lot of the elite cyclists in Europe die young because the nature of their sport demands that they often race when carrying a viral infection like flu. Fortunately, most of us are not in that position, so we can take the sensible option and rest!

Ignoring the warning signs

Now, onto the more important stuff – how do you avoid this, and what do you do with this information? A key point is that a lot of people ignore early warning symptoms, literally running into further trouble. The main early warning signs are chest pain, excessive shortness of breath, and abdominal pain. One story, documented in the literature, actually found that a runner did a 64km training run with severe chest pain, which forced him to walk numerous times, before doing the Comrades Marathon. During Comrades, he suffered a fatal heart attack. It’s been reported that about 81% of runners who suffer heart attacks during running had experienced and ignored chest pain or some symptom before “the main event”. So the bottom line – don’t ignore the signs!

So where does that leave you as a runner?

Assuming you’re a runner, then, you’re in a pretty strong position. But not an invincible one. Research has shown that in those people who have some sort of undetected heart disease, the risk of sudden death during exercise is massively reduced by regular exercise training. However, these people are more likely to have a heart attack while they exercise than while they are at rest. Hopefully that is clear – exercise reduces the overall risk by a factor of almost 100, but if the runner has a condition that will cause a heart attack, there’s a greater chance of it happening while they exercise. So as a regular runner (we hope!), you can be happy in the fact that you are about 100 times less at risk that your non-running colleagues. But you are not immune and so looking after the health of your heart, which includes checkups and tests, is still important, so that any symptoms of heart disease can be treated early. And should you stop exercising because you MIGHT be at greater risk? Well, no, because the data show that if you do this, and stop training, then your risk goes up massively. So no matter which way you look at it, it’s far better to continue running and training. In fact, if you’re reading this and you may have some sort of coronary artery disease, then you, of all people, would be best off by doing regular exercise, because the beneficial effect is the greatest.

So keep running, be aware, educate yourself and never take chances. Any chest pain, any shortness of breath, have it checked out. But don’t stop running. I’m sure that’s how Jim Fixx would have wanted it. The famous runner and author, who wrote some of the definitive books on the running “boom” of the 1970’s once wrote

“runners are much like ordinary mortals. They can, sad to say, get sick. They can even die”.

True, but less often and with reduced risk compared to non-running ‘mortals’, so keep running!

R & J


Anonymous said...

What a great co-incidence, I have just discovered your blog and I have a relevant question for this topic. A month ago I went for a check-up, and was told by my doctor that I have high blood pressure and cholesterol. I run every day, between 30 and 60 minutes, and compete in some trail running races. My doctor wants to put me on medication, because he suspects my problem is hereditary. I’m a little worried that it will impact my running performance? And also weather it is safe to run (hard) when taking medication for these conditions? Are my competitive days over?

Ross Tucker and Jonathan Dugas said...

Hi there,

First, you should know that we are PhD's and not MD's. Therefore we are not medical practioners, and you should always seek medical advice from a licensed doctor.

Having said that, we are not aware of any effect on performance of cholestroel lowering medication, although this would depend on what type of drug it is and its mechanism of action.

Next, exercise has a profound effect on controlling hypertension. Many factors affect hypertension such as age, diet, and genetics, but if you exercise every day for 30-60 min this should be helping you control your hypertension. Only your age would then be a good reason to go on hypertensive medication, for example if you are perhaps 60 or older.

Can you get a second opinion? We would suggest seeing a specialist such as a sports clinician at a cardiac rehab facility. These doctors are trained in how exercise can be used as a successful intervention in chronic diseases of life style such as heart disease and hypertension.

Running "hard" can be an issue if you have hypertension or heart disease, and again depending on your age. As you age your risk increases, and therefore it is a good idea to run with a heart rate monitor to keep your heart rate within prescribed limits.

The bottom line is that cardiac risk is the combination of many different clinical variables plus your age and your sex and activity level. With the limited amount of info you have provided here, it is difficult to make real conclusions about your scenario.

Good luck, hope this helps.

Kind Regards,
The Sports Scientists
Ross and Jonathan

Anonymous said...

Thanks for the feedback, I suppose I should have given more details, I'm a 34 year old male (a little young to be worried about these problems, I though?) and I've been running for about 6 years now, also been following the usual lifestyle advice (cut salt / sugar / fat / red meat, eat vegetables / fruit etc. etc.)

That's why I got worried when the doctor said there might be a problem, since I assumed I was already living a healthy lifestyle.

In fact, I don’t think I can live much healthier than I already am, so medication does seem inevitable. My main concern is thus the impact of the medication.

I do however think I'll take your advice and seek a second opinion from somebody who’s a little more involved in sport.

Once again, thanks for the feedback.

PS. Also been running with a heart rate monitor for years...

Ross Tucker and Jonathan Dugas said...


Just to add - there are a couple of classes of BP medication. Often, they will first give you what is called a diuretic, and they have a very minimal effect on exercise performance. If that doesn't work, they can then choose between using something called a B-blocker, or an ACE inhibitor - technical names, I know, but don't worry about that.

The important thing is that the B-Blockers do have quite a large negative effect on performance, the ACE inhibitor group doesn't. So it's worth telling the doctor specifically that you need to keep exercising, and therefore need a class that will not affect you too badly. If the doctor can't comply with that request, then you certainly would need to think of another opinion!

Then the final thing is that you might even want to consider having your BP measured over an entire day (they call this an ambulatory measurement), because BP is known to fluctuate, and is it possible that your previous measurement just came at a time when your BP was on the high side?

If that's the case, then perhaps you normal BP is actually lower and normal? If not, then I would do further investigation, because usually, when someone is active, healthy and still young, high blood pressure is rare, and may be an indication that further tests are required. Without meaning to scare you, a doctor would not normally just classify someone as having hypertension given the circumstances here. So look into a more complete BP measurement and take it from there, perhaps?

Good luck
Ross and Jonathan

Anonymous said...

Medication only treats the symptom! When will (most) doctors start treating the CAUSE! The cause of CAD is cholesterol! It's true...look it up.

To have the best health (not to mention performance) research WHERE cholesterol comes from and STOP eating it! It is such a no brainer but many don't link it up.

Cholesterol is found in ALL animal proteins. Think you can't perform without animal protein...ask Carl Lewis, Edwin Moses, Ruth Heidrich, Brendan Braizer, Tim VanOrden, etc.

A good book is Thrive by professional Ironman Brendan Braizer.

ps If you start eating a healthy diet (which is defined as a diet with NO animal proteins and LOTS of raw veggies/fruits) please contact your physician because your cholesterol and bp meds will drop you SO quick you will have orthostatic hypotension and malabsorbtion problems.

Ross Tucker and Jonathan Dugas said...


Can't help feeling you've missed the point of the post somewhat - it was never meant to convey the best treatments for CAD, that's a separate issue altogether. This post was really a news insight post looking at the specific case of Salazar as applied to other runners who may be wondering about the fact that a super-fit elite athlete could suffer from such an event.

So our intention was never to advocate any form of prevention - of course it comes up, it's material to the argument. And so we agree with you 100%, but I don't think that it was the crucial message we were communicating. You are of course, correct, but this was not the ideal occasion to advocate it.


Anonymous said...

I am 61 years of age and after running 18 marathons I had a triple by-pass surgery about four months ago. While training for a half marathon, I ignored chest pains for six weeks. During tha half marathon, i had chest/shoulder pains for the first 11 miles, I ignored it. Due to intense running my heart had developed collateral arteries and I think they protected me from a heart attack. My recommendation to all runner is that go see a Cardiologist and get certified by him before you run any marathon.

Anonymous said...

it would seem a discussion of diet should take place here. it has been shown through change of diet you can reverse and prevent heart disease.
from my understanding a lot of heart attacks are caused when small blockages break free and make their way to the heart.
it would be interesting to know what Jim Fixx"s diet was like.

Stephen Walker, PhD said...

Hi guys,

Thanks for the good science here. My area of expertise involves health and sport psychology. My work is focused on mental conditioning for peak performance, however, this research and a very scary personal experience (similar to Alberto Salazar's) has long had me exploring this topic in earnest for several reasons - not the least of which includes the desire for a long and happy life. I come from a nightmare of genetic contributors to CHD, however, I've been ever vigilant and maintained an active lifestyle & excellent physical condition.

As both a healthcare provider and patient - I've been amazed at the ways in which this field has evolved...or hasn't evolved.

Cardiology as a medical discipline has maintained very controversial positions on preventive measures that I believe are very well documented. Whereas a subcommittee in the American College of Cardiology (SHAPE (stroke/heart attack prevention) has strongly advocated for EBCT heart scans and certain blood tests that identify inflammatory markers that cause platelets to become sticky - think clotting factor) - cardiology - as a collective - has focused on the best practices in managing cardiac events not preventing them.

In my case, a dental infection precipitated an inflammatory response that landed me in the coronary care unit. In 1996, who would have known? However, the science is much better now and the research has been extensive. However, the financial players in the USA have directed what is covered and whats not - never mind the research.

An EBCT heart scan and a slightly more elaborate blood test (either VAP test or PLAQ) test would have undeniably identified my risk. On a research effort I participated in with the Denver Bronco Alumni - it was determined that a risk stratification protocol is not only the way to go - but can offer an immense cost savings (prevention vs. treatment.) I write about this research in a posting on my own blog: "What Every CEO-COO Should Know About the Cost of a Heart Attack" - www.PodiumSportsJournal.com

I'm confident that your analysis on Ryan Shay's and Alberto Salazar's conditions is noteworthy, however, I also know that sudden cardiac arrest is not always from an electrical derivation. Unstable plaque burdens, stress hormones, inflammatory markers in the blood, etc. can play a much larger role than previously considered (think water quality of the blood vs a plumbing problem caused by deteriorating pipes.) Internal medicine specialists that understand this dynamic are much better suited to engage in preventive cardiology.

Even after many years, the standard protocols for evaluating a person's risk of HA in the USA begins with a treadmill and ends with angiography - the relative costs of risk stratification vs. traditionally conducted medical screening (covered by insurance vs EBCT/PLAQ testing(which is not)...I am finding the best medicine (aka preventive) is often not recommended since many physicians won't prescribe any test that is not included in an insurance carrier's formulary.

Not only could President Clinton's heart condition been diagnosed years earlier - the judicious employment of prescriptive medications and lifestyle adjustments would likely have enabled him to avoid a dangerous and horribly intrusive CABG surgery. Ever the optimist, I'm hoping new revisions in the health care plan recently adopted will properly emphasize prevention.

Thanks for addressing these issues and for providing a forum for discussion.