Legend has is that a Greek soldier by the name of Pheidippides, ran from the plains of Marathon to Athens Bombay
Historians
contested this version of Pheidippides, and in fact later discovered that he
had run well over 450 km, over a ten day spell and was instrumental in saving
the battle for the Greeks.
Unfortunately, for our Bombay Braveheart (I am not naming him, in respect
for privacy), and his family his death is undisputed, and I extend my deepest
sympathies to his family and friends.
As is to be expected, this running death has created grave concern within the running fraternity of Mumbai, of which I consider myself an
integral part (both, as a runner and as the Medical Director of the Standard
Chartered Mumbai Marathon). In the
media, and in the running community I have encountered polarized views on the
risks of long distance running. One view
is that exercise in general, and running in particular is extremely healthy,
and therefore cannot be harmful by any means.
The opposite view is that running is dangerous and if one wants to
exercise, nothing beats a leisurely walk.
In my opinion, neither of these views is absolutely true, since this is
a complex topic and needs a deeper understanding rather than knee-jerk
one-liners. The purpose of this article
is to try and shed some more light on the risk associated with marathon
running.
Before we begin, I would like to clarify that this article
is not about the benefits and risk of exercise in general. The health benefits of exercise have been
unequivocally established, and these benefits very clearly outweigh the
risks. Also, this article deals with running half and full marathons, and not distances beyond that. There is new literature emerging on the
cardiovascular effects of ultramarathons, which can be discussed separately.
In 2012, a study was published in the New England Journal of
Medicine, titled ‘Cardiac Arrest during Long-Distance Running Races’. This
looked at the incidence of cardiac arrests in marathon and half-marathon races
in the United States
from 2000 to 2010, and included 10.9 million runners. In that entire period there were 59 sudden cardiac
arrests, of which 42 were fatal.
Sudden
cardiac arrest occurs when the heart suddenly and unexpectedly stops beating.
When this happens, blood flow to the brain and other vital organs stops, and
can lead to death if not treated within minutes. In fact, this year at the SCMM marathon we
had a sudden cardiac arrest, and due to a combination of luck and medical
preparedness we were able to save the runner (for more on that, read here: http://drcontractor.blogspot.in/2013/01/a-miracle-on-race-day.html).
The following is the information we learned from the Cardiac Arrest study:
- Cardiovascular disease accounted for the majority of these cardiac arrests and deaths
- The incidence of arrests was significantly higher during full-marathons than half-marathons, and was higher among men than women
- The incidence rate of cardiac arrest during half and full marathons was 1 per 184,00 runners
- The incidence rate of death during half and full marathons was 1 per 259,000 runners
- The commonest cause of death was hypertrophic cardiomyopathy
According to official figures, about 10 deaths take place on
the Mumbai suburban railway network each day, and approximately 7 million
commuters travel each day. This translates into 1 death per 700,000 commuters.
In other words, the risk of dying during marathon running is a little more than
double that of taking a ride on the Mumbai local trains! I know this is not a fair or scientific
comparison, and I do not mean to trivialize even a single death, but the idea
is to put the risk in perspective, which in absolute terms is very low.
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WHAT CAUSES THESE ARRESTS AND DEATHS?
The two most common causes of death found during this study,
as well as others looking at exercise and acute cardiovascular events were:
- Hypertrophic cardiomyopathy
- Atherosclerotic coronary artery diseases (blockages in the arteries)
Hypertrophic cardiomyopathy (HCM) has been defined as a primary disease of the myocardium (the muscle of the heart) in which a portion of the myocardium is hypertrophied (thickened) without any obvious cause (source: Wikipedia).
It has been well
established that among young individuals, less than 30 years of age, HCM and
other birth related (congenital) abnormalities are the main cause of
cardiovascular events.
It was also
thought that in athletes over the age of 30, atherosclerotic coronary artery
disease (which is just the scientific way of saying ‘blockages in the heart
arteries’) is the most frequent cause of cardiac arrest and death. Vigorous exertion was thought to lead to
rupture of the blockage, leading to clot formation, which leads to an
abnormal heart rhythm knows as ventricular fibrillation and ultimately death.
The surprising
finding in the New England study was that HCM
was also the leading cause of death in the population studied during the ten
years of marathon running, including the older runners. Several of the deaths were due to a
combination of HCM and blockages in the arteries.
OTHER CAUSES OF DEATH:
Besides the cardiovascular causes, hyponatremia (low sodium
level in the blood), and hyperthermia accounted for a total of about 10 percent
of the deaths. These remain important
concerns during long distance running but are not common causes of death.
WHAT CAN BE DONE TO REDUCE RISK?
This is clearly the most important question at the end of it
all. In my opinion, risk can be reduced
by taking care of the following:
- Pre-participation health check
- Paying heed to warning signs
- Sensible and appropriate training programs
- Medical facilities available during races
Pre-Participation health check:
Before you read any further, it is important to acknowledge
that the human body is an extremely complex organism. There is no definite testing protocol which
can completely rule out risk, which is why you occasionally have the scenario
of someone suffering an attack, even though they recently passed their medical
evaluation with flying colours. Having said that, these are the tests I
recommend, and the reason for each:
- ECG: this is certainly not a perfect test, but is a great starting point to give a basic indication of your heart function. It’s a great test to pick up HCM
- Fasting sugar, lipid profile, blood pressure, body mass index and weight circumference: all of these will give an indication of your ‘cardiac risk profile’.
- Stress test: one can debate the necessity of a stress test, but I would recommend it for two reasons. It’s a great indicator of your cardiovascular fitness, if nothing else and may indicate the presence of blockages in your arteries. One can criticize it for two reasons too: blockages show up on the stress test only when they reach a certain size and are ‘obstructive’ to the flow of blood. Often, there are smaller plaques which are the ones that actually rupture and cause the attack. Also, stress tests often show up ‘false positive’ tests, wherein no abnormality exists even though the test is abnormal (for some strange reason, doctors call it ‘positive’ when it is abnormal). Let the physician conducting the test know that you are a marathon runner and to allow you to carry out the test till you reach maximal fatigue.
- 2 D- echo: this is a great test to assess heart valve functioning, and the pumping capacity of your heart muscles. It’s also a great test to rule out HCM. It is relatively expensive, and if you are younger and asymptomatic I guess it would be fine to just do a simple ECG.
The most important part of the evaluation is to consult with
a physician who ‘understands’ exercise and the kind of program you hope to
embark upon. In addition to the above
tests, your medical and family history is vital. Data from individual tests do not have as
much meaning as the combined risk profile.
Warning Signs:
Several studies have shown that individuals who experienced
cardiac events during exercise, often had mild warning signs and symptoms,
which they or their physician chose to ignore.
The most common of these, which occurred a week before their arrest were
(as reported by friends and families):
- Chest pain
- Increasing fatigue
- Indigestion / heartburn /gastrointestinal symptoms
- Excessive breathlessness
- Ear or neck pain
Appropriate training programs:
All exercise programs should be progressed gradually. Most arrests and deaths occur in individuals
who participate without adequate preparation or those who ramp up their
training exponentially. At the end of
vigorous physical exertion it is important to cool down appropriately
(something which most of us, including myself do not do), since reduced blood
supply to the heart may be exacerbated by abrupt cessation of activity. This is the reason that runners often
collapse immediately after finishing an intense race.
Medical facilities on race day:
It goes without saying that adequate medical facilities
should be available during long distance runs, especially those exceeding 10
km. In addition to medical facilities, I
personally feel that every runner should take it upon himself or herself to
learn the technique of CPR (cardiopulmonary resuscitation). In the event of a
cardiac arrest, good CPR can be life-saving.
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TAKE-HOME MESSAGE:
Long distance running can be a safe and enjoyable sport with
considerable health benefits. There is a
small amount of risk involved which can be kept to a minimum by making sure you undergo a
‘running-specific’ health check, train sensibly and pay heed to warning signs
and symptoms should they occur.
References:
1. Cardiac Arrest Duing Long-distance Running Races. Kim et al, NEJM 2012;366:130-140
2. Exercise and Acute Cardiovascular Events: American Heart Association Scientific Statement: Circulation 2007;115:2358-2368
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