Marathons and long-distance running: the benefits and risks for the heart – watch out for the warning signs

A sedentary lifestyle is a formidable enemy of the heart and arteries. However, excessive or overly prolonged exertion can also prove harmful to the heart if one is not properly prepared. Caution is therefore required, bearing in mind that for those who run for long periods and engage in endurance activities such as marathons, the cardiovascular system responds differently from person to person, depending on age, gender and fitness level. These are the three variables that affect performance and health, according to research published in BMJ Open Sport & Exercise Medicine, (first author Inarota Laily), which examined the stresses the heart undergoes during prolonged running and the organ’s responses, with a potential risk of long-term maladaptation. In short: whilst it is true that a sedentary lifestyle can increase the risk of death, endurance exercise is also capable of inducing acute changes in cardiac function, with an increase in enzymes and proteins that may indicate tissue damage and inflammation, thereby affecting health outcomes.

The specialist’s advice: “‘Exercise is good for you, but as Alessandro Manzoni would say, “cum judicio” – comments Stefano Carugo, Professor of Cardiology and Head of Cardiology at the Milan Polyclinic, as well as a marathon runner. Physical activity is important, but you mustn’t overdo it’.”

The researchers examined 69 studies (49 of which were ultimately included in the analysis) involving 3,274 people, predominantly men, aged between 27 and 63. They looked at three biomarkers (cardiac troponin T – cTnT; cardiac troponin I – cTnI; N-terminal pro-B-type natriuretic peptide – NT-proBNP), which are indicative of cardiac wall stress or myocardial damage, whilst also analysing targeted tests such as echocardiography or magnetic resonance imaging. It was found that all three biomarkers were consistently elevated within the first hour after the end of the marathon, exceeding the clinical thresholds commonly used to diagnose myocardial damage, ischaemia or heart failure. Not only that: following the race, there were changes in the heart’s ability to pump the blood required by the body – specifically in the left ventricular ejection fraction, which measures precisely how much blood is pumped by the left ventricle with each beat. To be clear: these were minor changes. And there were no abnormalities detected on MRI scans. Whilst the research suggests that a marathon does not cause visible signs of clinically significant structural myocardial damage, it is important to bear in mind that greater caution is required as women get older and, of course, depending on their level of fitness.

The three parameters considered influenced the impact of changes in biomarkers and the echocardiography findings. In short: in conclusion, following prolonged exertion there are indeed increases in cardiac biomarkers and evidence of alterations in ventricular function, but it is difficult to assess their clinical significance. So let’s not exaggerate. “Running a marathon is incredible,” says Carugo. “But running too many and asking your body to go the extra mile isn’t healthy. That’s what the published article says, and I’d add a piece of advice: the ideal number is two marathons a year.” With the right training, of course.”

To be beneficial, physical exercise must be tailored to the individual. Above all, it must not place excessive demands on the body, particularly in terms of cardiovascular risk. So, the first rule is to remember to train sensibly and not to go overboard. You should start gently, beginning with short bursts of aerobic exercise (which supply the body with oxygen), such as a slow run, cycling or swimming. Then, gradually, you can increase the duration of your activity. Finally, for those over 40, it is best to avoid activities that cause sudden changes in muscle tension, involving short, intense bursts of effort: this includes, for example, padel or five-a-side football. To some extent, the environment also plays a part in assessing the risk-benefit balance: if you are untrained and not in good health, being in the mountains – compounded by hypoxia (i.e. a lack of oxygen) – places significant stress on the heart and blood vessels. And this may be difficult to sustain. To know whether you are overexerting yourself – especially if you suffer from high blood pressure or your heart is not in the best of shape – shortness of breath and the inability to exchange a word with the person next to you should serve as a warning. Equally important, once you have been given the all-clear by a specialist following a stress test or other investigations, is to monitor your maximum heart rate, simply by checking your pulse.