Alarm fabric that is released during intensive exercise does not indicate unhealthy coronary arteries

It is a mysterious paradox that scientists still have not found the answer: exercising is healthy and reduces the risk of heart conditions, but for a long time and intensive exercise is also a heavy burden on the heart muscle.

It has been known for some time that the protein troponin is released in the blood during exercise. That is the same substance that doctors at the Emergency Department measure in patients who have had a heart attack. With such an infarction, part of the heart muscle dies due to insufficient blood supply, after which the troponin level in the blood rises. The more troponin, the greater the damage to the heart.

The protein is therefore seen as an alarm dust that predicts the health of the heart, but why is the presence so increased after exercise, and what is the case with the heart of these athletes?

Researchers from the Radboudumc found a reassuring answer to that question and published Monday about it in it Journal of the American College of Cardiology. Increased troponin after exercise is not an indication of clogged coronary arteries – the blood vessels that provide the heart with blood. « Good news for the athletes, » says lead researcher and movement scientist Thijs Eijsvogels. « But this outcome raises a lot of new questions for science. »

Calculated crown arteries

Eijsvogels and his colleagues tied up existing insights about troponin together for a new research question. « In a study we did a few years ago with participants of the Nijmegen 4Daagse, we already saw that the troponin content of the participants was a predictor of heart problems and early death, » says Eijsvogels. « But we didn’t know why it was, what role troponin played in it. »

The researchers seemed to have found a suspicion for that causal link in a study that showed that athletes suffer from the crown arteries more often than non-athletes. « Logically, we therefore suspected that athletes with a high troponin content after exercise have an increased degree of coronary arteries, which in turn gives a higher risk of heart problems. »

To be able to test that hypothesis, the researchers tackled it in a big way. They followed more than a thousand participants in, among others, the Nijmegen 4daagse, the Zevenheuvelenloop and the Tour of Nijmegen. Walkers, runners and cyclists, all between forty and seventy years old. Before and after exercise, their troponin content was measured via blood collection. Within three months, ten percent of the participants went through the CT scan to measure the health of their coronary arteries.

« We really wanted to look at the extremes of the spectrum, » says Eijsvogels. « That is why we scan the 6.6 percent of the participants with the highest troponin content, sometimes ten times higher than the healthy limit, and the 3.3 percent with the lowest content, corrected for age, gender and the type of effort. » What turned out? Contrary to what the researchers thought, athletes with a very high troponin level had no unhealthy coronary arteries at all than people with low troponin values.

Leaking heart cells

For years, according to Eijsvogels, it was assumed that the release of troponin is a normal response of your body on sports. That changed when various studies suspected that troponin in your blood may not be as good as thought. Because troponin is heart -specific – it only occurs in the cells of heart muscles – it was precisely the consensus that increased troponin is always wrong: it can only be released if there is damage to the heart muscle.

But it can also be something else, says Eijsvogels now that he is looking at his own results. « We also investigated 11 participants in the Amsterdam marathon by getting them through the MRI scan. There we saw that their heart muscle cells seemed to be leaking after exercise. The higher their troponine content, the stronger the leakage of the heart muscle cell. But then the question remains: what does the degree of leaks of your heart go? After exercise, without this is harmful.

For that reason, the researchers will continue to follow their more than a thousand patients in the coming twenty years. They receive a questionnaire annually, and the researchers keep up with the death register. Although the study by Eijsvogels has invented its own hypothesis, it is good news for athletes. « Even with an elevated troponin there is not suddenly anything wrong with your heart. »

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