A new study published by the American Heart Association has found that running full marathons may significantly increase strain on the heart. A team of experts based in Spain found elevated concentrations of several biomarkers of cardiac strain among amateur runners.
Measuring the levels of cardiac-specific troponin T or troponin I in the blood can help identify damage to the heart. The researchers compared levels of these two cardiac biomarkers in 63 amateur runners. The team also measured levels of biomarkers for cardiac tissue stress.
The tests were conducted after the subjects ran an endurance race of three different lengths including a full marathon, a half marathon, and a 10K race. Initially, there was little difference in the risk for cardiovascular events between the runners. After the full marathon, however, the strain on the heart muscle was found to be much greater.
The incidence of cardiac arrests in marathoners is very low, affecting only about 1 in 50,000 runners who compete in races. Regardless, a high proportion of all exercise-induced cardiac events happen during marathons, particularly in men aged 35 and older.
Study lead author Dr. Juan Del Coso is the director of the exercise physiology laboratory at Camilo José Cela University in Madrid, Spain.
“We typically assume that marathon runners are healthy individuals, without risk factors that might predispose them to a cardiac event during or after a race,” said Dr. Del Coso. “But with the growing popularity of long-endurance races, the exponential increase in the number of participants, and the lack of appropriate training in some cohorts of amateur runners, our findings suggest that running shorter endurance races might reduce the strain imposed on the myocardium during running competition.”
The study is published in the journal Circulation.