Early childhood and pre-adolescence represent critical windows for cardiac and vascular maturation. Regular athletic training during these periods elicits a spectrum of functional and structural adaptations collectively termed the “pediatric athlete’s heart.” While such changes are generally benign, distinguishing normal sport-related remodelling from incipient pathology is essential for safe training progression. The present mixed-methods study synthesises current international evidence and reports original longitudinal data from a cohort of 168 healthy Uzbek children (8–12 years) enrolled in organised endurance or mixed-sport programmes. Over twelve months every participant underwent serial echocardiography, cardiopulmonary exercise testing, heart-rate-variability analysis and duplex assessment of carotid arterial compliance. Linear mixed-effects modelling showed that weekly training volume independently predicted physiological increases in left-ventricular (LV) mass index (β = 0.11 g·m⁻²·h, p < 0.01) and stroke volume, paralleled by resting-heart-rate reductions of −5.7 ± 1.9 beats·min⁻¹. LV end-diastolic diameter remained below age-adjusted upper reference limits in 95 % of athletes. Vascular indices improved, with carotid distensibility rising 6.4 % and intima-media thickness falling 4.1 % relative to non-sport controls. No child developed maladaptive wall hypertrophy or arrhythmogenic events. The findings corroborate contemporary paediatric sports-cardiology literature by confirming that supervised training enhances cardiorespiratory fitness without provoking pathological remodelling. Periodic, guideline-based screening and training-load individualisation are recommended to sustain these benefits.

Pediatric athlete’s heart, cardiac remodelling, echocardiography

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