Electrocardiographic Changes in Juvenile Athletes in Relation to Sex, Age, and Sport Category.

Regular physical activity in young athletes leads to significant cardiovascular adaptations, often reflected in changes observed on electrocardiograms (ECG). The aim of this study was to relate ECG changes to age, sex, and sport category to provide a more in-depth understanding of physiologic adaptations to training. This retrospective study included 600 healthy Caucasian children (5-17 years) undergoing preparticipation evaluation (PPE) in 2023-2024 consisting of thorough medical and family history, physical exam, and resting ECG. The study found that the most common adaptive ECG changes in young athletes were sinus bradycardia < 60/min (24.2%), incomplete right bundle branch block (iRBBB) (15.5%), and sinus arrhythmia (SA) (11.8%). More significant bradycardia < 50/min was found in 3.5% of athletes. Borderline or abnormal ECG findings were found in 3.5% of participants, but later studies confirmed the presence of a high-risk condition in only two athletes with pre-excitation pattern (0.33%). Sinus bradycardia was independently predicted by age, sex, and sport category, iRBBB and early repolarization pattern by sex and age, LVH only by sex and SA, and T-wave inversion in V1-V3 only by age. This study highlights that while adaptive ECG changes are common in young athletes, particularly in males and with increased age and training, the prevalence of high-risk conditions is low. Knowledge about the factors affecting adaptive ECG changes should help in clinical decision-making in juvenile athletes.