Acute impact of first-time marathon running on the heart in middle-aged men.

BACKGROUND: Middle-aged men seem to be particularly susceptible to adverse cardiovascular effects of endurance exercise. The acute impact of training, marathon finishing and recovery on the heart has not been extensively investigated in such at-risk novice marathon runners. METHODS: We prospectively quantified cardiac changes in middle-aged men (41.2±4.5 years; n=17) who participated in their first marathon run at four time points: at baseline, after 16 weeks of training, within 10 hours after completing the 2021 Amsterdam Marathon run and after 4 weeks of recovery. Measurements included comprehensive 3-Tesla MRI examination, echocardiography, ECG and blood sample assays of high-sensitivity troponin-T (hs-TnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP). RESULTS: Acute effects associated with finishing the marathon run were a <10% reduction in left ventricular end-diastolic volume in absence of other morphological changes, and only minor changes in systolic contractile mechanics and diastolic filling patterns. Neither quantitative myocardial mapping with MRI nor late gadolinium enhancement revealed any signs of post-marathon myocardial injury. ECGs did not reveal any abnormalities. Circulating levels of hs-TnT and NT-proBNP had increased markedly after the marathon, with hs-TnT exceeding the clinical upper reference limit for all participants. All observed marathon running-induced effects were transient. CONCLUSIONS: Extensive phenotyping using state-of-the-art quantitative imaging modalities paired with physical assessments and blood assays in this selected cohort offers no evidence to support the notion that first-time marathon running in healthy middle-aged men has a detrimental impact on the heart.