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Marathon: risks and safety

vinayakhingane - November 28, 2018 - 2 comments

हा लेख मराठीत वाचण्यासाठी लिंक:

We all know that exercise is good for our health but few believe in it whole heartedly. The world is divided between exercise lovers and haters. It is difficult for some people to experience the ‘bliss’ of endorphins after a good session of exercise. There seems to be a reason behind it. Some experiments show that the chemical response in body to exercise can differ significantly in different individuals. Some experience a ‘high’ due to secretions of chemicals like endorphins and endocanabionoids. On the other hand, some simply do not produce enough of these chemicals in reaction to the exercise. So they tend to dislike exercise for the discomforts and the muscle soreness that follows. Despite all these factors, people do exercise; if not for pleasure, for the health benefits exercise brings. The scientific evidence for exercise is quite substantial. Most doctors and health agencies prescribe exercise. There is a general consensus that exercise is good for us. The only question remains as to how much exercise is actually good and when does it become too much.

            Endurance sports are known to offer tremendous stress to the body. In a marathon and a half marathon one has to run for 42 km and 21 km respectively. However people seem to like this challenge and we now see increasing number of runners every year in marathons. Some endurance sports like triathlons are even more challenging. A person with a heart condition or illness would not attempt such a challenging physical activity. The people who participate in endurance sports are considered to be virtually healthy . This is one of the reasons why most people are shocked to learn about deaths during a marathon run. They start wondering if marathon and similar events are safe. The media exclusively covers all the events of collapse and deaths during a marathon. Social media also pays enormous attention to these events. Similar instances from the past are retold as a reminder. The articles about dangers of running marathons spring up like mushrooms. However some information is dubious. Most of us are not convinced but these articles usually succeed in creating a lingering doubt. I have seen experienced runners getting worried about the risk of running a marathon. Some people get so worried that they do not let their loved ones run in any event. I was approached by some patients and readers enquiring about my opinion on the risk of endurance sports. I gave it a thought and would like to share some scientific articles which might help you make an informed opinion on this subject .

              The biggest concern regarding long distance running is about the number of deaths during marathons. We usually presume that the participants are healthy. This makes these deaths unacceptable even though the number is small. The increasing number of collapse and deaths in the last few years has been a cause of worry. However , we need to consider these numbers closely. The ‘denominator’ is an important part of statistics that is hardly discussed in the media. There was an excellent study conducted in America by Jonathan Kim, Rajiv Malhotra and colleagues which was published in the New England Journal of Medicine in 2012. America had witnessed a total 59 cases of cardiac arrests among 10.9 million runners from years 2000 to 2010. They found out that the risk of collapse and death was more in marathons than half marathons. Around 1in 2 lakhs collapsed in half-marathons while same happened to 1 in 1 lakh during a marathon. They could save around 30 percent of those who had collapsed. That makes the risk of death even lesser. This study mentions that the numbers of cardiac arrest during these long distance running events were less than the number of cardiac arrest occurring in middle aged males jogging in routine life. The study concludes that marathons and half marathons have low general overall risk of cardiac arrest or sudden death.

A similar study in Japan showed the number of collapse due to cardiac arrest to be around 1 in 50000. They had a better survival rate in Japan and around half of those collapsed survived the cardiac arrest. So that makes one death in 1 lakh runners. Similar numbers were seen in England. After considering studies from all over the world experts opine that we can expect one cardiac arrest every year and one death every 2 to 3 years in a field of 50000 marathon runners. The experts generally consider marathons to be fairly low risk. I haven’t found any data for Indian running events. I would like to imagine that the numbers of cardiac arrest would be similar in an Indian setting. The survival rate may differ in different parts of the nation. Some cities have excellent healthcare facilities while some places are simply not at par. However overall number might not differ significantly to international estimate. These numbers are not as bad as portrayed by the social media. If we were to compare these numbers to the number of deaths on Indian roads due to traffic accidents, they would shock us. Around 1,37,000 people died in road accidents in India in 2013. This was published by NDTV based on data by various sources including National crime records bureau and Global status report on road safety 2013. This article also states that 5 people die every day on Delhi roads. There were around 1214 road crashes killing around 377 people daily. So if we consider the numbers, it appears that driving on Indian roads is riskier as compared to running a marathon. It is ironic that the everyday news of death in a road accident hardly causes any reaction but the rare death in a running event scares everyone to the core!

The number of deaths do not tell us the complete truth. For understanding the risk of endurance sports, we need further information. There are studies about causes of deaths amongst marathon runners. The American study mentioned above also looked into this matter. They found out that amongst all the cardiac arrest cases 52 percent had Cardiomyopathy (which means disease of heart muscle). Majority of these had a specific kind of heart muscle disease called ‘Hypertrophic Cardiomyopathy’. This is a medical condition where the heart muscle is deformed and enlarged in some parts. This causes obstruction in the blood flow when heart rate accelerates. These people are also at increased risk of abnormal heart rhythm and sudden death. This is a genetic condition and people are usually do not show symptoms at rest and routine daily work. There could be a history of sudden death in the family. In the same study, they found that the chances of revival after cardiac arrest are less in patients of hypertrophic cardiomyopathy. This disease is often goes undetected as the  person looks healthy and has no significant complaints. This disease is an important cause of sudden death during a sporting event. Some tests like electrocardiogram (ECG) and Echocardiography can help in identifying this condition.

We have an electrical system in our hearts which makes it run rhythmically. If there is some problem in this system, the heart rhythm may go haywire and can lead to death. This is called ‘arrhythmia’ in medical terms. This arrhythmia could be triggered in stressful conditions . This could be a silent medical condition and a person may not experience any problems for long time. An prolonged ECG recording is carried out in symptomatic people. Around 14% of those who had cardiac arrest were found to have such rhythm problems in above mentioned study. Undetected coronary artery disease (usually called as heart attacks ) was found in 16 % people. Around 7 % of those who died had low levels of sodium in the blood and 3 % had died due to heat stroke. Cause of death could not be identified in around 3 % people.

It is clear from above data that the majority of those who collapsed had some form of a hidden heart condition. If such conditions could be diagnosed beforehand, these deaths could be avoided. There are certain check-ups and tests for young athletes before major events like Olympics. Similarly, before a sporting event , one should have a complete physical check up , an ECG and blood tests to understand current health. This needs to be looked at by an expert physician especially if there is coexisting obesity, hypertension, diabetes or any other medical condition. The American study also points out a very interesting thing. Usually heart attacks happen due to rupture of fat laden ‘plaques’ in the arteries. This causes formation of a sudden clot in the coronary arteries which leads to heart attack. They found out that this was not the case in case of runners. Most of them had a heart attack due to inability of the coronary arteries to supply enough blood to the fast running heart. This happens due to stiff and thick coronary arteries which fail to dilate . This led the authors to think that a stress test (or treadmill test) could be useful to such patients before marathons. If someone develops a problem during stress test, then he should not be a candidate for long distance race. This stress test might give a false positive result which means that there may not be actual blockage in coronary artery but the test may still be positive. It’s because of this reason that stress test is not routinely advised. But the observations of the study and opinion of authors indicate that it could be used as a helpful test before long distance running. Especially in people with risk factors. There are some studies which indicate that taking an tablet of aspirin can help in reducing the risk. People who have conditions like obesity, hypertension, diabetes , kidney diseases and people with family history of cardiac deaths have higher risk of death than normal population. Similarly, individuals with symptoms like chest pain, shortness of breath, dizziness after exercise are at increased risk. The echocardiography and stress test can also be useful in such people apart from the routine ECG.

Doctors can identify people at risk identifying some hidden cardiac conditions with physical examination and tests. It is wise to undergo such examination before training for any sport. The risk of sudden collapse is more in new and inexperienced athletes. Also, the risk is higher in people with sedentary life style who suddenly decide to run a marathon. Preparation for a marathon is of paramount importance. It is usually suggested that one should prepare for around 4 to 6 months for a marathon. In this period , one is expected to practice for 3 to 5 days a week and gradually build up the stamina. There should be adequate time for rest and recovery. Such thoughtful preparation gives our body a chance to withstand stress of marathon. There are programs like ‘Couch to 5K’ in UK where people are helped to start an activity and slowly increase the endurance. Marathon or any long distance running is not something to ‘try’. It needs careful planning .


Long distance running stresses not just the heart but our whole body. Muscles, bones, lungs, kidneys and other organs, all face the stress of the exertion. This stress could be immense, especially in challenging weather conditions and may lead to other dangers. Our body loses sodium with our sweat. During marathons, this minor loss could turn out to be significant. If a runner drinks a beverage without any salt (like plain water ) during a marathon, the sodium levels in blood could drop to dangerously low levels. This is called hyponatremia in medical terms. Adding salt to drinks can help in preventing this problem. Adequate water intake keeps our body working properly. During a marathon run, muscles can get damaged due to over exertion and this may lead to leaking of myoglobin from the muscle into the blood. The myoglobin is a big protein compound which can obstruct functioning of the kidneys. If one is dehydrated then it puts additional stress on the kidneys as well. Staying hydrated also helps in regulating the temperature of our body. This will give you an idea about how important it is to keep drinking enough fluids with electrolytes. The drink should contain enough salts to maintain sodium level. Adequate carbohydrate intake is equally important before a marathon. Carbohydrates are our energy source and need to be replenished to cope with the efforts of a marathon. People on diet and trying to lose weight should bear this in mind. Food and drink need a careful thought before attempting a sporting event, Planning it ahead of the event helps and reduces the risk of developing complications later.


India has hot climate for most part of the year. This presents new challenges. There is a certain danger of heat stroke in hot climate. Heat stroke is a condition where the body fails to regulate its temperature and the body temperature starts going up. This could prove fatal. Wearing suitable clothes, staying hydrated and getting acquainted to the weather conditions are some things that can prevent a heat stroke. Excessive fatigue, dizziness, vomiting or feeling sick are some of the symptoms of heat stroke. If you experience any of these then you should stop and seek medical help immediately. A fever also increases the risk of heat stroke. So even minor infections and viral fevers should not be ignored. If you have a fever or are not feeling well, it is better to avoid a run.

Running, like other sports, has an inherent risk of injury to muscles and joints. Good preparation is again a key to evade this. A well prepared athlete is less likely to sustain an injury. I believe that coaches and trainers can help you in avoiding a injury . There is usually a fear of damage to the knees amongst the general public. Some studies however show that running could actually be beneficial for health of the knees. Athletes have shown to have many health advantages over people with sedentary lifestyle. So overall benefits of running are more.

We have so far talked about efforts at individual level. Organisers should also try to provide infrastructure for safe marathons. Early CPR (cardiopulmonary resuscitation) and prompt use of defibrillators have shown to improve the survival in case of a cardiac arrest. Provision of such facilities and medical backup can help. The record of adverse events and medical problems can help in further identifying risk factors. I recently visited Spain where a marathon was conducted at night. Such policies can be used in India to avoid heat strokes.

Marathons and long distance running events have some definite risks as they puts lot of physical stress on the body. This risk can be reduced by proper preparation and training before a marathon. Individual factors also play a role. Some individuals have high risk while some have low risk. Such individual risk assessment can be done with physical examination and medical tests. People with high risk can avoid marathons or can seek professional advice. Although it is a tough physical challenge, Marathon is not as dangerous as portrayed by the media. If you want to run a marathon then there are safe ways to do so. You need to acknowledge the risk and effort involved and prepare for it. Staying away from the ‘fads’, avoiding scaremongering and seeking help from experts are some ways to make it easy.

Dr Renuka & Dr Vinayak
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