Short-term effects of marathon running: no evidence of cardiac dysfunction

The purpose of this study was to analyze the short-term effects of a marathon race (Madrid Marathon) on both markers of cardiac damage and echocardiographic parameters in a group of 22 runners (17 male and 5 female; 34 +/- 5 yr; VO2max: 55.7 +/- 9.1 mL x kg(-1) x min(-1) with a wide range of fitness levels.

Venous blood samples were collected from each subject 48 h before the race, at race finish, and 6, 24, and 48 h postexercise for the determination of myoglobin, total creatine kinase catalytic activity (total CK), mass concentration of creatine kinase isoenzyme MB (CK-MB mass), and cardiac isoforms of troponin T and I (TnT-c and TnI-c, respectively). In addition, echocardiographic parameters (M-mode two-dimensional and Doppler analysis) indicative of both left ventricular (LV) systolic and diastolic function were obtained three times from each runner: 2-5 d before the race, at race finish, and 24-36 h after exercise.

Except in one subject, levels of TnT-c and TnI-c were within normal limits (<0.1 ng x mL(-1)) in all the samples collected before or after the race. Overall LV systolic function was not altered by marathon running. Finally, LV diastolic function was transiently altered after the race since the ratio between peak early and late transmitral filling velocities (E/A) was significantly reduced at race finish (P < 0.01) and returned to resting levels after 24-36 h.

Our findings suggest that marathon running does not adversely affect the hearts of healthy individuals independently from their training status.