Deaths of participants in long-duration events such as marathons regularly reignite the debate over the appropriate amount of physical exercise to maintain good cardiovascular health. A recent cardiac imaging study(1) carried out in old recreational athletes who have practiced endurance sports all their lives suggests that beyond a certain limit, there are very, very active people who can develop a “heart of stone”.
Blocked heart arteries
Many are prone to the development of chronic diseases such as type 2 diabetes, dyslipidemia (disorder in the transport of blood cholesterol), and coronary heart disease.
In some people, coronary heart disease develops because of the buildup of cholesterol in the arteries of the heart. These thicken and harden due to a calcification process, and thus become fragile. When the inside of an artery ruptures, it releases different substances that will produce a thrombus (clot), which can lead to a heart attack or stroke.
Measuring atherosclerosis
The abundant scientific literature on how to prevent the development of these diseases is very clear. Regular physical activity, such as a good 30-minute walk, 5 times a week, generates many important cardioprotective effects.
But can you exercise too much? Computed tomography angiography (an imaging technique) now makes it possible to examine the structure of the heart and quantify atherosclerosis (blockage) of the coronary arteries in a non-invasive manner. Using this tool, a team of researchers from the Netherlands has been studying for several years a group of male amateur athletes initially aged on average 54 years (MARC-1 study) who were re-evaluated 6 years later (MARC-2 study)(1). Since 289 of these men participated in both studies, the stability or progression of their atherosclerosis could be assessed. It is also relevant to mention that a significant proportion of these amateur athletes trained at a vigorous intensity (44%) or even very vigorous (34%).
Vigorous exercise and calcification of the coronary arteries
The results of this study are fascinating. The presence of calcification in participants’ coronary arteries increased from 52% to 71% during follow-up and their calcium score also increased over 6 years. Furthermore, despite their regular and vigorous training, an increase in the number of atherosclerotic plaques was observed in 75% of these athletes. That said, researchers observed no association between training volume and changes in calcium score or number of atherosclerotic plaques. However, the practice of very vigorous exercise was associated with the progression of the calcium score, hence the expression “heart of stone”.
The dangers of a heart of stone – distinguishing very active people from inactive people
Is too much high-intensity exercise dangerous for amateur athletes? Care should be taken not to overinterpret images of calcified coronary arteries. In the general population, the higher the calcification of the coronary arteries, the greater the risk of heart attack. However, in athletes, the prognostic value of this score remains uncertain since athletes have more stable atherosclerotic plaques and less fragile rupture, which explains their lower cardiovascular risk and their longer life expectancy than the population. in general.
So the question remains: can you exercise too much? In a cardiac imaging study, my colleague at IUCPQ – Université Laval, cardiologist Éric Larose, reported that after a marathon, the runners’ hearts had developed edema, but that everything had returned to normal. order after a few weeks(2). Does the significant physiological stress associated with long-term events generate an inflammatory response which stimulates the calcification process and which would explain the “heart of stone” of certain endurance athletes who have abused their body and their heart? ?
Being sedentary and inactive is more dangerous than being too active!
Don’t worry, the majority of us have some room to go before concluding that we’re exercising too much! If you play very long, high-intensity sports, do it for passion, not necessarily for your heart health. Additionally, make sure you always give your body and heart time to recover, sleep well, and listen to yourself. If you feel unusual fatigue during a workout that you would normally do comfortably, talk to your doctor. Keep in mind that being sedentary will always be much more dangerous than being physically active!
(1) Aengevaeren VL et al. Exercise Volume Versus Intensity and the Progression of Coronary Atherosclerosis in Middle-Aged and Older Athletes: Findings From the MARC-2 Study. Circulation 2023;147(13):993-1003.
(2) Gaudreault V et al. Transient myocardial tissue and function changes during a marathon in less fit marathon runners. Can J Cardiol 2013;29(10):1269-1276.
