The Observation Of Junior Middle Distance Runners' ECG QTd Before And After 21km-Running

Purpose of the Observations: ECG QT interval dispersion (QTd) can reflect changes in ventricular recovery time zone, which represents the inconsistency of ventricular repolarization; it is currently used in clinical as a simple, reliable, non-invasive diagnosis of cardiac disease indicators. As young athletes'cardiac development is not yet mature, exercise training can play a positive role in their cardiac development, but it may also have a negative effect, After training, if the runners'QTd value increased, the athletes may be at risk of myocardial injury; if after the exercise the QTd value decreased, the exercise may be positive to athletes'cardiac development. By combining experiment result with Serum cTnI levels of cardiac index, this thesis systematically observed the changes of junior athletes'QTd level after acute endurance training, it aims at providing both theoretical and practical references for the arrangement of medical supervision and training plan.Research Method: This is the first study targeted on young athletes, using the indicators of ECG and the cardiac injury markers as testing method to diagnose junior middle distance runners'QTd value, QTdc value of ECG changes and related indicators after a 21km-run, and analyzed relationship between the two with the combination with changes in cardiac index of serum cTnI levels. In the process of one year's training, I repeated these testing of athletes to observe the changes of QTd reproducibility; I also observed the changes of QTd level, QTdc level and related standards of athletes and non-athletes in quite state.Research Results:1. The QTd and related indicators of junior middle distance runner after running 21km have decreased compared with that before exercise; the measurement of their serum cTnI values 4h after exercise indicates that 68.4% of them exceeded the myocardial injury threshold, and 26.3% exceeded the acute myocardial infarction threshold; the ECG QTd, QTdc value and the serum cTnI levels of Athletes were not related before or after exercise.2. After a year of training, the repeated observations of athletes'QTd and QTdc changes indicates that changes were little in the first two before-exercise experiments, but the changes caused by training in the second after-exercise was significantly higher than that of the first.3. In quiet state, the QTd, QTdc and relative values of athletes that had been trained for a year were lower than that of non-athletes.Conclusion: 1. The reduction of QTd value in acute endurance is positive for the improvement of junior athletes'cardiac function and the adaptability of their heart.2. As indicated by the significant achievement of one year's training, moderate endurance exercise can influence young people's heart development positively.3. There are difference between the cardiac function adaptability of junior athletes who had received professional endurance training and that of young people who had never received such training, this indicates that endurance training started in teenage time is positive to the improvement of junior athletes'cardiac function adaptability.