The heart of the futsal athletes: a comparison of heart structure among under-18, under-20 and adult elite players.

Introduction: This study examined cardiac adaptations in futsal athletes to determine how sport-specific training influences cardiac morphology and function across different competitive levels. Methods: Male athletes from under-18, under-20, and adult categories underwent electrocardiogram, transthoracic echocardiogram, and cardiopulmonary exercise testing. Measured parameters included VO₂max, ventricular and atrial dimensions, wall thickness, and cardiac mass index. Group differences were analyzed using one-way ANOVA with Tukey's post-hoc test (p < 0.05). Results: Under-20 athletes showed significantly higher VO₂max compared to adults (mean difference: +4.87 mL·kg-1·min-1; p = 0.014). Adult players exhibited greater interventricular septal (+0.68 mm; p = 0.048) and inferolateral left ventricular wall thickness (+0.75 mm; p = 0.016), alongside higher left atrial volume (+27.4 mL vs. U18; p < 0.001) and indexed left atrial volume (+14.6 mL/m² vs. U18; p < 0.001). Conversely, the right ventricular end-diastolic diameter was larger in under-18 athletes compared to under-20 (+10.9 mm; p < 0.001) and adult players (+14.3 mm; p < 0.001). Ejection fraction, left ventricular end-diastolic diameter, and ventricular mass index remained consistent among groups, confirming preserved systolic function across all athletes. Conclusion: Progressive futsal training promotes selective cardiac remodeling characterized by increased wall thickness and chamber dilation in adult athletes without compromising function. These adaptations reflect physiological remodeling associated with chronic high-intensity intermittent training, emphasizing the need for longitudinal monitoring to distinguish normal adaptation from early pathological changes.