HealthDay News — Running a marathon can increase cardiac strain in amateur runners, according to a research letter published online December 3 in Circulation.

Beatriz Lara, PhD, from Camilo José Cela University in Villafranca del Castillo, Spain, and colleagues selected 63 healthy runners (in triplets) from a group of 322 nonprofessional finishers. Runners were matched for age (mean age, 37 years), anthropometry (66.9kg), running experience (3.3 years), and 10-year absolute cardiovascular risk (2.8%). From each triplet, one runner competed in a 10km race, a half-marathon race, and a full-marathon race. Blood samples were obtained to measure cardiac biomarkers.

The researchers found that self-reported perceived exertion ratings measured with the Borg scale were similar for all races (P=.17). After the races, the serum concentrations of cardiac troponins I and T were significantly higher across running distances. N-terminal pro-B-type natriuretic peptide and creatine kinase-MB concentrations were higher only in marathon runners. Similarly, a correlation for higher serum concentration with running distance was found for serum myoglobin (P<.01) and creatine kinase-MM concentrations (P<.01). 

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“These data suggest that the strain imposed on the myocardium by competing in a full marathon is much greater compared with competing in shorter distances such as the half-marathon or 10km races,” the authors write.

Abstract/Full Text