Legend has is that a Greek soldier by the name of Pheidippides, ran from the plains of Marathon to
to announce that the Greeks had just defeated the Persians, in 490 BC. The distance he ran was 42.2 kilometers,
which has then become the official distance of a ‘marathon’. Legend also has it that after announcing the
victory, he collapsed and died. 2500
years later on February 24, 2013 a brave citizen of Athens ran the half marathon in Thane, and at
the end of the race he proudly collected his medal. After receiving his coveted prize, like
Pheidippides, he too collapsed and died, despite intense efforts to revive him
by the doctors present there. 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
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.
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.
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.
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.
1. Cardiac Arrest Duing Long-distance Running Races. Kim et al, NEJM 2012;366:130-140