It was a remarkable studyin January in the scientific journal circulation. The more intensively middle-aged men exercise, the faster the blood vessels of their heart muscle calcify. Arteriosclerosis is not a good thing, we all know that: the phenomenon is strongly related to heart attacks and strokes. The worse the condition of your vessels, the sooner you die on average. But wasn’t exercising healthy? Didn’t athletes actually live longer? Should we all exercise less intensively?
These are the questions that Vincent Aengevaeren, cardiologist-in-training at Radboudumc in Nijmegen, has been working on for years. “During my medical studies I already found cardiology very interesting,” he says. “And at that time I also played a lot of sports myself: running, skating, cycling, fitness, tennis. Then I became fascinated by the beneficial effects of sport on health.”
Aengevaeren conducted PhD research into the possible negative effects of sport on the heart. “Everybody used to think that marathon runners would have perfectly healthy blood vessels,” he says. “It later became clear that they could indeed have coronary artery calcification.”
Constipation can cause a heart attack
Arteriosclerosis, or rather arterial calcification and even more officially atherosclerosis, can arise in all kinds of blood vessels. Cardiologists mainly look at the coronary arteries: the vessels that supply the heart muscle itself with blood. It is dangerous if they become severely narrowed or even clogged. The heart can beat less due to a lack of oxygen, resulting in heart failure. Blockage can cause a heart attack, and a loose clot can lead to an infarction elsewhere.
“Sports lowers the risk of all these disorders,” says Aengevaeren. “Among other things by improving vascular function, blood pressure, fat composition in the blood and sugar regulation.” But then German researchers discovered in 2008 that marathon runners actually had more coronary artery calcification than the general population. “After that it was quiet for a long time. But I found it super interesting. That’s what I wanted to investigate: what the relationship is between health and the level of exercise. Whether you can exercise too much.”
More data is available for men
Why is he specifically researching this in men? “Coronary artery calcification is more common in men than in women,” Aengevaeren replies. “Sudden cardiac death during sports is even 92 percent of cases in a man. Why this is the case is not yet entirely clear. But in any case, this means that there is much more data available on men.”
The recent study in circulation followed nearly 300 sporting men for about six years, on average from their 54th to their 60th year of life. “Two measures are important,” says the researcher, “namely how much and how intensively people exercise.” For the latter measure, researchers look at how much energy that effort costs per hour, compared to our resting metabolism. Those who run briskly, for example, use almost twelve times as much energy as someone at rest. The men in Aengevaeren’s study exercised the equivalent of about four hours of brisk running per week on average.
“We saw two striking things,” says the cardiologist-in-training. “The more intensively the men exercised, the more their coronary artery calcification increased over those six years – and also the more often we saw that their plaques were calcified.” Plaques are thickenings in the vessel wall in which inflammatory cells, cholesterol and calcium have accumulated. All this is what we popularly call arteriosclerosis – a normal aging process of the arterial wall, which is strongly related to how healthy you live.
Sharp spikes in adrenaline, heart rate and blood pressure
Aengevaeren does not know why the plaques calcify more during intensive exercise. “Perhaps it has to do with the sharp spikes in adrenaline, heart rate and blood pressure, which put more strain on the arterial walls,” he speculates. “Perhaps their magnesium balance is different – and magnesium affects vascular calcification. Or maybe you get different blood flow profiles during very intensive sports. I would like to find out all about that.”
The key question, of course, is: are these men really more at risk of heart attacks and strokes? “We don’t know that well yet, because the long-term effects have never been properly researched,” says Aengevaeren. “Yes, we know that coronary artery calcification is strongly related to cardiovascular damage. But at the same time, we know that the more you exercise, the longer you live. Perhaps there are other effects of sports that compensate for the negative effects on the heart.”
For example, that the coronary arteries of fanatical athletes are wider and function better. That the extra calcification actually makes their plaques firmer, making them less likely to rupture. Or that there is another, unknown factor that makes these men healthier on average. “We don’t really know,” says Aengevaeren. “I find it super intriguing.”
Until then, he does not want to give firm sports advice. Except for this: “Exercising is better than not exercising – that applies to almost everyone. And it is important that you exercise in the way you like best. Then there is the greatest chance that you will persevere.”