The benefits of physical activity for preventing the occurrence of cardiovascular diseases have long been scientifically validated, and are the subject of reliable recommendations. The French Cardiology Federation recalls in particular that “30 to 45 minutes of moderate physical activity per day (walking briskly for example) reduces the risk of cardiovascular accident by 30% on average”.
But be careful not to overdo it, especially after a long break. Indeed, practicing intense sporting exercise without precaution can trigger a myocardial infarction or cardiac arrest. It has even been shown that among the factors triggering heart attacks, vigorous exercise is one of the most powerful (25).
Do not panic, however: not only is this type of accident very rare, but also, the majority of them occur in people who are usually not very active, or sedentary, during unusual physical activity. Respecting a few rules and practicing appropriate physical activity therefore makes it possible to limit the risk of occurrence.
Who is concerned ? What are the warning signs? What good practices should be observed to limit risks? Here are the answers given by science.
Which sports (and which athletes) are concerned?
The heavy media coverage of cardiac events occurring in competitive athletes, such as the one that struck Danish footballer Christian Eriksen during Euro 2020, does not reflect the scale of these accidents. The vast majority of them occur most often among participants in recreational sports, whose numbers are much larger. Thus, among all cases of sudden death linked to sport, it has been estimated that only 6% occur during competitive sport, compared to 94% during recreational sporting activities.
According to the sports classification of the European Society of Cardiology, the sports concerned are mainly endurance and high intensity sports. Studies on the subject reveal that approximately 70% of cases occur among runners, swimmers, cyclists, hikers, soccer players and tennis players.
Every year, in France, around 1000 sudden deaths occur during sporting activity. This figure should be put into perspective with the overall number of sudden deaths occurring in our country. In fact, between 30,000 and 50,000 cases of sudden deaths occur every year in France, with an incidence between 50 and 100 cases per 100,000 person-years (1 per 1000 in developed countries).
But as we said before, these accidents are rare. Overall, it is considered that around 5% of these sudden deaths occur during a sporting activity.
Why do these accidents happen?
Little known for a long time, we now know more about these exercise-induced cardiovascular events. Analysis of currently available data reveals that their occurrence is linked to age and associated cardiovascular risk factors: high blood pressure, diabetes, smoking, high levels of bad cholesterol, excess weight or obesity…
In young people, these accidents generally occur due to an undetected anomaly. This can sometimes be acquired (inflammation of the heart muscle), but most often it is of genetic or congenital origin.
After the age of 35, cardiovascular accidents induced by exercise result in 80% of cases from a process of atherothrombosis: the rupture of an atherosclerotic plaque induces the formation of a blood clot obstructing the lumen. of the coronary artery (thrombosis). Atherosclerotic plaques are made up of blood cells and “bad” cholesterol (LDL cholesterol). They accumulate over the years on the internal wall of the arteries causing them to thicken, harden and reduce elasticity, hindering the flow of blood.
Coronary accidents are therefore more likely to affect adults and seniors. They mainly occur in patients suffering from multiple lesions on their coronary arteries, characterized by a narrowing of the caliber of these blood vessels supplying the heart (multivessel coronary artery disease).
Although we now know better the risk factors, the mechanisms by which physical exercise triggers an acute cardiac event are not yet clearly identified. The rupture of the atherosclerotic plaque could be favored by the increase in mechanical stress on the vascular wall induced by exercise.
However, the occurrence of myocardial infarction could also be linked to mechanisms other than obstruction of the coronary artery lumen. Indeed, an imbalance between the supply and demand for oxygen of the cardiac tissue (myocardial ischemia) can occur during exercise, when a stable calcified atherosclerotic plaque is present and causes narrowing of the artery (stenosis). fixed).
What symptoms should alert you?
The symptoms of a myocardial infarction linked to sports practice are defined as those of a classic infarction. Typically, it is intense chest tightness-type pain, radiating to the jaw and/or left arm, prolonged and resistant to usual pain medication. Sometimes it may be a change in the characteristics of usually moderate pain which subsided quickly and did not alarm us.
However, sometimes the symptoms differ: the infarction can sometimes result in abnormal shortness of breath, discomfort or unexplained dizziness (with, at most, loss of consciousness), palpitations or even digestive symptoms in people having no history of digestive pathology.
Symptoms occur during physical exertion, or within an hour following exercise, during the recovery phase.
Few studies have been carried out on French territory, but an observatory recently set up at the level of a French department (IMACS) indicates that subjects who presented a cardiac event linked to sport experienced in almost one third of the cases of pain upstream, which however did not lead them to consider a medical consultation (which would perhaps have made it possible to avoid the said cardiac event).
These data, consistent with others, suggest that there is an important opportunity to prevent these cardiac events.
Difficult screening
One of the problems is that the coronary disease at the origin of cardiovascular events induced by physical exercise is frequently asymptomatic, and is therefore not always detected.
Furthermore, training makes it possible to partially compensate for coronary blood flow by increasing the diameter and/or density of the arterioles. It also improves vasomotor reactivity (the adaptive capacity of vessels to dilate or narrow depending on myocardial needs).
It is possible that in certain cases, these beneficial vascular adaptations allow subjects practicing sporting activity to manage the reduction in myocardial blood flow induced by the presence of atherosclerotic plaques. The consequence is that they experience few symptoms before the acute accident, despite the extent of their coronary lesions.
How to assess your coronary risk?
Coronary risk is assessed using the SCORE (Systematic Coronary Risk Evaluation) scale, based on the recommendations of the European Society of Cardiology. This is a diagram which makes it possible to predict the risk of occurrence of a lethal cardiovascular event over 10 years, in presumed healthy individuals. It is adapted to the European population, for cardiovascular prevention in clinical practice.
The major variables that enter into this model are sex, age, smoking status or not, blood pressure and total cholesterol. They make it possible to categorize the population into low cardiovascular risk, moderate risk, high risk and very high cardiovascular risk.
The stress test (exercise electrocardiogram) is generally only recommended in symptomatic subjects, or those presenting certain cardiovascular risk factors, in particular arterial hypertension, dyslipidemia (high level of bad cholesterol or HDL cholesterol, triglycerides, or both), diabetes, active smoking or a family history of heart attacks (that is, if immediate family members, father, mother, brother or sister, had a heart attack before the age of 55 years or, in the case of women, before menopause).
This test consists of recording the electrical activity of the heart during sustained physical exercise. In addition to the detection of rhythm disturbances and the assessment of blood pressure during exercise, it makes it possible to detect the electrical signs of myocardial ischemia induced by physical exercise (imbalance between oxygen supply and demand heart tissue).
Who is at risk, and what precautions should you take?
People with the cardiovascular risk factors mentioned above are more likely to develop a cardiovascular event.
Physical activity is of course very beneficial for these patients, but they should keep in mind that the risk associated with vigorous exercise is increased, and take precautions accordingly. The prevention of these events therefore requires adapted and individualized screening before practicing sport.
Epidemiological data indicate that particular surveillance should be carried out in middle-aged men practicing leisure sports, who constitute a population particularly at risk.
A medical examination with an electrocardiogram to screen for possible cardiac pathologies and abnormalities is recommended for the latter, as is the assessment and screening of cardiovascular risk factors in order to identify people at high risk. coronary events that require additional testing.
Before 40 years
The prevention model cited above cannot be directly transposed to individuals under 40 years old. Before the age of 35, the recommendations of learned societies are indeed contradictory.
While some recommend carrying out a systematic electrocardiogram before practicing sports, others emphasize primary prevention, in other words all measures aimed at preventing the appearance of cardiovascular problems (eating correctly, not not smoke, treat high blood pressure if necessary, etc.), which could play a major role in limiting the risk of premature onset of coronary heart disease.
The type of sport, and in particular the importance of the cardiovascular demand it induces, must also be taken into account.
Play sports, but not just any way
The practice of regular physical activity obviously remains a particularly effective strategy for preventing cardiovascular diseases, there is no doubt about it. Overall, active people have a lower cardiovascular risk than others.
However, it is important to respect certain good practices, such as those proposed by the Club of Sports Cardiologists.
Lack of awareness of the risks that poorly adapted sports practice can pose sometimes results in harmful behavior, the consequences of which can be aggravated by ignorance of suspicious symptoms. Although they are, fortunately, not always fatal, the psychological and societal impact of cardiac events is significant. It is therefore better to limit the risk of occurrence.
This article was written by Miwakan researcher Isabelle Macoucou Kouame and published on the site The Conversation.