Abstract
Sudden cardiac death (SCD) in athletes is generally rare, but a serious complication of cardiovascular events during exercise. Although regular intensive physical exercise is thought to be a key to a healthy life, unsuspected pathologies might lead to SCD during or after physical activity. Cardiac dysfunction and elevated cardiac markers have been reported after prolonged exercise. We sought to clarify the cardiac marker levels and hydration status in healthy, middle-aged male subjects for 24 hours after running sixty-minute at race-pace. The participants were 47.4±1.7 years old, had peak oxygen consumption of 47.1±1.2ml/kg/min, and regularly running 70.5±6.4km/week. Blood biomarkers were performed before, immediately after, at the fourth and twenty-fourth hours after running. Compared to initial values, creatine kinase (before:161.2±22.5U/L, 24 hours after:411.9±139.7U/L, p<0.001) and CK-MB (before:4.3±0.7ng/ml, 24 hours after:10.1±3.0ng/ml, p<0.001) were significantly elevated immediately after running and remained significantly high for 24 hours. In addition, Troponin-I (before:5.0±1.1ng/l, 4 hours after:81.5±29.9ng/l, p<0.001) and NT-proBNP (before: 31.2±5.3pg/ml, immediately after: 64.4±8.5pg/ml, p<0.01) were significantly elevated immediately after running and returned to baseline levels in 24 hours. The sixty-minute running caused significant dehydration, but athletes were rehydrated at the 4th hour in their voluntary hydration behavior. As the individual data were analyzed, it was interesting to see that some of the athletes had critical biomarker levels without any cardiac symptom. Our findings indicate that race-pace sixty-minute running may induce a possible transient silent myocardial injury in apparently healthy master runners. Detailed pre-participation screening of these athletes may be necessary to reduce the risk of SCD.