RESUMEN
A follow-up data on electrocardiogram (ECG) and blood pressure (BP) changes in adolescent athletes are scarce. We compared ECG and BP between adolescent athletes and nonathletes in a 4-year follow-up. A total of 154 youth sports clubs (SC) in Finland and 100 secondary schools for comparison data participated in this observational follow-up study. Those who maintained or adopted SC participation are referred to as 'Always athletes' (n = 137), those who never participated in SC as 'Never athletes' (n = 108) and those who dropped out ofSC during the follow-up as 'Changers' (n = 116). The mean age of the participants was 15.5 (0.6) years in all study groups at baseline. Resting ECG including heart rate, PR interval, QRS duration, QRS axis, QRS amplitude, T axis and QT interval and BP were measured from all participants at baseline and after follow-up. 'Always athletes' had lower resting heart rate, more negative T-wave axis and higher QRS amplitude than 'Never athletes' at baseline and at 4 years (p < 0.05). 'Changers' had lower resting heart rate, more negative T-wave axis and higher QRS amplitude, systolic BP and pulse pressure than 'Never athletes' at baseline (p < 0.05). None of the observed differences at baseline, were visible at 4 years (p > 0.05) except the difference in T-wave axis (p = 0.028). The significant group × time interaction between 'Changers' and 'Never athletes' was found for QRS amplitude (p = 0.017). Adolescent athletes have several training-induced cardiovascular adaptations, which return towards the levels of nonathletes after cessation of regular training.
