Experts agree that moderate exercise reduces your risk of cardiovascular disease, but the exact mechanisms are not completely clear. Does it keep your blood vessel healthy, increase the electrical stability of your heart or just improve your metabolism? As endurance athletes are health-conscious, it is not clear either how much of the benefits are due to a healthy lifestyle and how much to exercise.
Moreover, recently some scientists have wondered if strenuous exercise, such as marathon running, could be more harmful than beneficial. I have blogged about this problem before.
To answer all these questions, Beth Taylor and her colleagues have compared the arterial stiffness, carotid artery wall thickness and cardiovascular risk factors (cholesterol, triglycerides, body weight…) between 42 Boston marathon qualifiers and their sedentary spouses.
Arterial wall thickness is a risk factor of cardiovascular disease, as it is probably one of the early stages of atherosclerosis.
There is more and more evidence that there is a relation between arterial stiffness and cardiovascular disease.
Several studies have looked at the influence of strenuous exercise on wall thickness and stiffness before but the results are contradictory, probably because other lifestyle factors, such as diet, are confounding them. As the sedentary partners had the same lifestyle as the runners but only performed moderate workouts, this study isolates the effects of strenuous exercise.
As suspected, the cardiovascular risk factors were better in the runners than in their sedentary partners. The arterial wall thickness and stiffness however, were not different.
The researchers concluded that exercise protects you by other mechanisms than by preventing atherosclerosis. This would then explain why scientists have found a large plaque burden in some runners. On the other hand, it once again shows that strenuous exercise is not bad for you, as the runners did not show an increased arterial wall thickness or stiffness. Hopefully, this will put an end to this lingering debate!
However, marathon running does not make you immune from cardiovascular disease, and you should always take any symptoms seriously.