Contrary to popular belief, running a marathon does not increase the risk of a heart attack. Health experts recommend nevertheless a medical checkup before embarking on such a race.
The image of the marathon runner who collapses, suddenly struck by a heart attack, just before or shortly after crossing the finishing line, is a troubling image that implants a seed of doubt in our minds. These tragic accidents, sometimes relayed by television cameras, are confusing. Sports, and in particular running, are, after all, supposed to improve our fitness and lower our risk of succumbing to a heart attack.
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A study published in the New England Journal of Medicine (NEJM) deals with this apparent paradox. Apparent because the authors of this study concluded that running a marathon (42, 195 kilometres) or a half-marathon “does not lead to an increased risk of heart attack”. According to them, this risk is, on the contrary, “low and even lower than that incurred by taking part in a triathlon or a jog”.
Mortality rate of 1 in 259,000
Dr. Aaron Baggish, of Massachusetts General Hospital, and his colleagues analysed such cases of heart attack among 10.9 million marathon runners and semi-marathoners between 2000 and 2010. Over the entire period, only 59 of these athletes suffered a cardiac arrest during and one hour after the race. Of those who suffered an attack, 42 have died resulting in a mortality rate of 1 in 259,000. This rate is 1 in 52,630 among those who take part in triathlons. The difference between the number of attacks and the number of deaths is due to the presence of medical personnel who could intervene quickly. So it is more likely to survive a heart attack during a marathon than if someone is at home.
A detailed study of these accidents and those deaths show that the majority of the victims suffered from cardiac deficiencies. In particular, the deaths were caused by hypertrophic cardiomyopathy, a condition characterised by a loss of elasticity of the heart muscle, making the heart less able to pump blood to the body. Since the age of the marathon runners have been increasing, many also suffered from atherosclerosis (deposit of plaques that reduce the blood flow to the heart). However, these problems can worsen when the person makes a violent effort, as during a marathon.
In addition to indispensable pre-deployment training, Dr. Aaron Baggish considers it essential that all candidates for this type of event first undergo a medical examination to detect possible heart failure. The risk of an individual depends on multiple factors such as high blood pressure and cholesterol, habit of smoking or family history of heart disease. In addition, it is important to ask the doctor about the risks and ways to minimise them.
Doctors’ recommendations include “no smoking one hour before and two hours after a sport” and “report to the doctor of any heart palpitation occurring during and just after exercise”. Such rules should however be obeyed by anyone who plans to do intensive aerobic exercise and is not reserved only for the marathon runners.
Researchers of the l’Institut de recherche biomédicale et d’épidémiologie du sport (Irmes) have observed that in most of the sports disciplines, athletes have reached a physiological limit since the 1980s.
‘Citius, Altius, Fortius’ or ‘faster, higher, stronger’ has been the motto of the Olympics. For Henri Didon, a French preacher who coined that motto, ‘it contains the basis and rationale behind athletics’. Yet, the creation of new world records may be in danger now.
A study by the Institute published in 2015 in the journal Sports Medicine reveals that the performance of athletes has stagnated over the last three decades. Not only has new records become increasingly rare, but the difference of measurement between the records has also decreased. ‘In a few years we will have to measure in terms of milliseconds to continue to have world records,’ said Jean-François Toussaint, Director of IRMES.
By analysing the ten best performances each year in 137 disciplines since the early 20th century, French researchers have noticed the appearance of a physiological ceiling in most disciplines since the 1980s. Thus, in the women’s 400 metre run, athletes are struggling for thirty years to cross the bar of 8 metres/second while the latter stood at around 7.3 metres/second in 1960. This same phenomenon is observable in many disciplines like men’s triple jump, swimming, 100m and 200m freestyle, or the archery. ‘We have reached that stage of human limitations,’ said Geoffroy Berthelot, computer scientist at IRMES and co-author of the study.
Many factors came into play in allowing athletes to go as fast, reach as high and be as strong as they can. Topping the list has been ‘the Cold War and the professionalisation of sports’ that boosted the spirit of competition and enabled a very rapid growth,’ says Geoffroy Berthelot. To always get the better of geopolitical rivals, techniques and race strategies have been refined, the movements optimised to decrease energy losses. Sometimes such efforts have been made in excess, with widespread use of drugs, particularly in countries like the erstwhile East Germany.
Specialisation by morphology
Technology too contributed to this development. Within a century, the equipment and the conditions in which athletes train and compete allowed them to gain a few centimetres or tenths of a second. ‘In 1936, when Jesse Owens set the 100m record, he ran on a track made of ashes of burnt wood. Today Usain Bolt runs on surfaces that waste less energy,’ recalls David Epstein, author of the book Le Gène du sport.
Once the insturments are set up, the athlete only has to give the best of herself to the limit set by her anatomy. ‘Today we know that every sport requires a different physical profile. To run the 100 metres, it is better to be big and powerful but it will be the exact opposite for a marathon runner,’ says Jean-François Toussaint. A remarkable example of this phenomenon of specialisation suited to one’s morphological profile is that of Michael Phelps, the champion swimmer and Hicham El Guerrouj, the 1500m record holder. They have an 18 cm difference in height, yet their legs have the same length. This is explained by the need to have a long trunk when swimming. An attribute to the contrary would penalise a middle-distance swimmer.
‘We cannot run as fast as a cheetah’
‘Athletes have understood that they would have to exploit their morphology in disciplines that best suit them,’ says the researcher. They may even have to abandon some sports in favour of others. So while the Scandinavians, with their imposing builds, dominated the middle distance in the 1970s, the rise to power of smaller African runners in the following decades caused a drop in the rankings of the Dutch athletes. The morphology of the Africans allowed them to achieve unattainable records and the Scandinavians gradually abandoned that discipline.
‘This factor of having a maximum limit in the performance is not bad,’ says Geoffroy Berthelot. ‘Humans are the only species who are able to understand nuclear physics. But we do not have the physical attributes to run as fast as the cheetah. We must accept it.’