In children and adults, endurance training increases resting stroke volume, mainly as a result of an increase in left ventricular (LV) filling.
Purpose: To evaluate whether the LV morphologic and functional alterations responsible for this increase in cardiac filling are similar in children and young adults.
Methods: Standard echocardiography (LV morphology and function) and tissue Doppler imaging (LV relaxation properties) were assessed in 10 adult cyclists, 13 age-matched sedentary controls, 12 boy cyclists, and 11 untrained boys.
Results: In our endurance-trained adults, LV morphological adaptations included increase in LV internal diameters, wall thickness, and mass. However, effects associated with training on LV morphology were different in children because no true cardiac hypertrophy was observed in our child cyclists compared with age-matched nonactive boys. Effects related training on LV systolic and diastolic function assessed by TDI were similar in boys and men. The LV diastolic function was improved in trained subjects (i.e., increased transmitral early to late filling velocities) as a result of an increase in LV relaxation properties. However, LV filling pressures, estimated from TDI, were similar in trained individuals compared with age-matched controls.
Conclusion: In both children and adults, an increase in LV relaxation properties and normal LV filling pressures in endurance-trained subjects might be taken as additional indicators for a physiologic or "normal" hypertrophy. However, further investigations are needed to evaluate whether the specific LV morphological adaptation observed in trained-children reflects a blunted trained-induced cardiac hypertrophy before puberty.