Early Cardiac Responses to Half-Marathon Running in Amateur Athletes: Implications for Cardiovascular Health and Safe Exercise Participation.

Background: Recreational half-marathon participation is increasing, particularly among middle-aged amateur runners, yet the interpretation of early post-race cardiac findings remains challenging in exercise-based cardiovascular health evaluation. This exploratory study assessed early post-race changes in left ventricular diastolic indices and circulating biomarkers in 20 healthy amateur runners (80% male; mean age 50.7 ± 12.3 years) after the 11th PELLA HALF MARATHON (21.1 km). Methods: Participants underwent transthoracic echocardiography and venous blood sampling within 30 days before the race and within 30 min after finishing. Diastolic assessment included the E/A ratio, tissue Doppler early diastolic myocardial velocity (e'), the E/e' ratio, isovolumic relaxation time (IVRT), and left atrial area. Biomarkers included C-reactive protein (CRP), creatine phosphokinase (CPK), creatine kinase-MB (CK-MB), and high-sensitivity cardiac troponin I (hs-cTnI). Results: Post-race assessment showed a consistent pattern of lower early diastolic filling/relaxation indices, higher IVRT and left atrial area, and significant increases in all measured biomarkers. hs-cTnI exceeded the sex-specific 99th percentile upper reference limit in 7/20 participants (35%). Conclusions: Half-marathon completion was associated with early echocardiographic and biomarker changes in this cohort of amateur runners. These findings are consistent with acute physiological cardiac stress and may help clinicians contextualise early post-race abnormalities when advising on vigorous endurance exercise participation. However, subclinical myocardial injury cannot be excluded without serial biomarker assessment and advanced imaging, and the findings should be interpreted as exploratory because of the small convenience sample, absence of a control group, lack of hydration assessment, and single early post-race timepoint.