Abstract
OBJECTIVE: The aim of the present study was to determine the effects of a well-controlled endurance training program on cardiac functions and structures in healthy children and to define whether training hours per week and type of sports affect the training-induced cardiovascular response. METHODS: Echocardiographic recordings were obtained in 126 children who systematically participated in sports training for at least 1 year (study group), and the results were compared with the values obtained in 62 normal children who did not actively engage in any sports activity (control group). The two groups were comparable for age, sex, and body mass index. Study group participants were divided into two groups according to the duration of physical activity (training hours per week, <8 h and >8 h) and five groups according to the cardiovascular demand of sports type. Clinical examination, resting electrocardiogram, two-dimensional, M-mode, and Doppler echocardiography were obtained in all participants. RESULTS: Left ventricle wall dimensions, left atrial diameters, and aortic measurements were significantly higher in the study group. The mean mitral E/A ratio was also significantly higher in the training group than in untrained subjects (p<0.001). Echocardiographic measurements were similar between different sports type participants in the study group. However, aortic root diameter, left atrial diameter, and left ventricle posterior wall diastolic thickness were higher in children training >8 h/week than in children training <8 h/week in the study group. CONCLUSION: The present study showed that the echocardiographic parameters of children participating in regular sports training activities statistically significantly exceeded the parameters of untrained controls. These parameters were mostly dependent on the duration of training hours per week.