The Study Of Changes In Serum Cardiac Troponins After Exercise And Its Pathophysiological Significance On Myocardial Tissue

The assessment of elevations of cardiac troponin T (cTnT) and I (cTnI) in serum, an immunoassay of the regulatory cardiac proteins, is recently considered as the"gold standard"biochemical test for diagnosis of myocardial damage. The increased cTnT and/or cTnI reported recently in adult athletes after endurance exercise supported the contention of the occurrence of exercise-induced myocardial injury.In the present study, some critical issues in sports medicine were investigated such as the pathology significance of exercise-induce elevation in serum cardiac cTnT and cTnI, the exercise-related factors that may predispose to cardiac damage, and the monitoring principle in training practice.At first, we examine the appearance and clearance characteristics of serum cTnT and cTnI in junior runners after an exhaustive 21-km run. It was found that some subjects'post-exercise peak values of cTnT and cTnI above the cutoff for myocardial injury or acute myocardial infarction, which reflected occurrence of exercise-induced myocardial injury. Further findings implied that the exercise-induced myocardial damage was partly dependent on subjects'training status. This also seemed to suggest that the appearance of serum cardiac troponins might be part of the normal cardiac adaptation to endurance exercise. Moreover, we explored the relationship between exercise load and cTn level. Body function was associated with the possible alternations of serum cTnT and cTnI entailed from different exercise-trials was also examined. It was found that the elevation of serum cardiac troponins in subjects was augmented with running distance. In addition, the consistent evidences of increased training impulse concomitant with the presence of myocardial injury evidence of increased cTnT and cTnI shown support the idea of the exercise load is important factor in exercise-induced myocardial damage. It was also found that the subjects with higher cortisol and testosterone/cortisol before exercise were apt to develop myocardial damage, which was not related to the immunity, iron status and oxidative stress of subjects.We also investigated cTnT before and after basketball games that include a significant high intensity and/or isometric muscle contraction component in junior athletes. The results showed that as long-distance running, intermittent high intensity sports also increase the risk of exercise-induced myocardial damage.The animal experiment's results suggested that prolonged swimming exercise-induced elevation of serum cTnT represented the reversibile myocardial damage. The difference in cTnT and pathology characteristic between the endurance exercise and a model of acute myocardial infarction (isoprenaline-induced cardiac injury) led a postulation that there seemed to be probability of exercise-induced irreversibile myocardial damage while the serum cTnT twenty-four hours after exercise was far higher than normal level.This research also suggests serum cTn might be an indictor of the exercise load in training monitoring for the first time, its advantages lie in assessing the risk of exercise-induced cardiac damage at the same time, fewer interference factor and standardized measurement.