Marathon Runners and Heart Problems

By Jane Farrell

If you’re just a weekend runner, better think twice about signing up for that grueling race.

Researchers say that full marathons (26.2 miles) may significantly raise concentrations of several biomarkers of stress in the heart.

The study appeared in Circulation, Journal of the American Heart Association.

The strain on the heart muscle is much greater after a full marathon.

For their investigation, researchers in Spain tested levels of the cardiac biomarkers in 21 groups of three amateur runners each. Each individual ran a marathon, a half marathon (13.1 miles) and a 10K (6.2 miles) as part of the study. The investigators compared levels of two of the cardiac biomarkers, including troponin I and troponin T after each person ran each race.

The conclusion: the strain on the heart muscle, as measured by the biomarker levels, was much greater after a full marathon.

The incidence of cardiac arrests in marathoners is only about 1 in 50,000 runners who compete in races, but a high proportion of all exercise-induced cardiac events occur during marathons, especially in men 35 years of age and older.

The number of subjects in the study was not large enough to accurately assess differences in 10-year cardiovascular risk, but the researchers are planning to examine this in a larger group of runners, said lead investigator Juan Del Coso, Ph.D., 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. 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,” Del Coso said.