[[Electrocardiogram in the pediatric athlete: physiological adaptations, borderline findings, and alarm criteria]].

Electrocardiographic (ECG) interpretation in the pediatric athlete is clinically challenging due to the interaction between cardiovascular growth, electrophysiological maturation, and exercise-induced adaptations. Unlike adults, the electrical phenotype in children and adolescents reflects a dynamic developmental process, leading to greater variability in ECG patterns. Accurate differentiation between development-related findings, physiological adaptations to training, and alterations suggestive of structural or electrical heart disease is essential to optimize early detection of clinically relevant cardiovascular conditions while avoiding unnecessary restrictions on sports participation. This review summarizes the electrophysiological basis of ECG findings in young athletes and proposes a clinically oriented classification of findings into physiological, borderline, and abnormal categories, integrating contemporary interpretation criteria. A practical approach to ECG interpretation and the rational use of complementary diagnostic testing is also presented, aiming to improve diagnostic accuracy and support safe sports participation in pediatric populations.