Biological maturation, muscular fitness and cardiovascular asymmetry in pediatric female athletes: associations with ECG conduction and inter-arm blood pressure differences

Background Cardiovascular screening in pediatric athletes remains challenging due to physiological adaptations related to growth, biological maturation and training. While electrocardiographic (ECG) changes during adolescence may reflect normal developmental remodeling, inter-arm blood pressure difference (IAD) has been associated with vascular risk in adults. The interaction between biological maturation, muscular fitness and cardiovascular asymmetry in young athletes remains unexplored. Purpose To investigate the combined influence of biological maturation and muscular fitness on ECG parameters and inter-arm blood pressure differences in pediatric female athletes, and to assess the one-year stability of ECG findings. Methods Twenty-eight female rhythmic gymnasts (6–14 years, 9.1±2.4 years) underwent resting 12-lead ECG assessment and anthropometric evaluation. Menarcheal status was used as an index of biological maturation. PR interval, P-wave duration, QRS duration and T-wave duration were analyzed. In a subgroup (n=11), ECG assessment was repeated after one year. Additionally, bilateral systolic and diastolic blood pressure and handgrip strength (HGS) were measured to determine inter-arm blood pressure difference (IAD ≥10 mmHg) and muscular asymmetry. Results Post-menarcheal athletes demonstrated significantly longer PR interval compared to pre-menarcheal peers (p=0.005), whereas no differences were observed in QRS duration, T-wave duration or resting heart rate (p>0.05). ECG conduction parameters showed high one-year stability (PR r=0.795; P-wave r=0.940; QRS r=0.843; p<0.001). IAD ≥10 mmHg was observed in a minority of participants and was not associated with menarcheal status. Handgrip strength correlated positively with systolic blood pressure but did not independently predict clinically significant IAD. Conclusions Biological maturation selectively influences atrioventricular conduction, reflected by PR interval prolongation, without affecting ventricular depolarization or repolarization indices. ECG conduction parameters demonstrate high temporal stability in young female athletes. Muscular fitness is associated with systolic blood pressure but does not explain inter-arm vascular asymmetry. These findings highlight the importance of integrating biological maturation into the interpretation of pediatric athlete ECGs while supporting bilateral blood pressure assessment as an independent screening component.