Electrophysiologic Study of Exhaustive Exercise

Background: Exhaustive exercise is well known to pose a variety of health hazards, such as sudden cardiac death reported in ultra-marathon runners. Depressed parasympathetic tone is associated with increased risk of sudden cardiac death, thus parasympathetic withdrawal in post-exercise phase may be a high risk period for sudden death. To date, the effect on cardiac electrophysiology after exhaustive strenuous exercise has not been described. The aim of this study was to evaluate the impact of severe exhaustive exercise on cardiac electrophysiology.
Methods: The subjects in ranger training were invited to participate in this prospective study. The parameters measured consisted of PR interval, QRS duration, and macro T wave alternans as well as corrected QT, QTc dispersion, Tpeak –Tend interval and Tpeak –Tend dispersion.
Results: The study group consisted of 40 consecutive male rangers who completed training and the control group (22 healthy age and height matched male subjects). In regard to electrocardiographic criteria, no differences were found between rangers before and after training program. In respect of the repolarization markers, there were no significant differences between the rangers before and after training program.
Conclusion: There was no significant change in cardiac repolarization markers after severe exhaustive exercise. Additionally, there was no relationship between sudden cardiac death and electrophysiologic changes after exercise.