Longitudinal Observation Of Cardiac Adaptation In Junior Rugby Players Using Echocardiography

Abstract

PURPOSE: The purpose of this study is to conduct a 3-year longitudinal study of cardiac adaptation in junior and senior high school athletes who play rugby with echocardiography in an effort to examine how continuous practice of rugby during the growth period affects ventricular volume expansion and ventricular septum thickening. METHODS: Subjects were 34 male junior high and 79 senior high school rugby players with top-level game power. Subjects engaged in rugby-related training approximately 3 hours a day, 6 days a week continuously for 3 years. We measured height, body weight, blood pressure and took electrocardiogram and echocardiography measurements once a year for 3 consecutive years in these subjects. Echocardiography measurements were taken by portable ultrasonic measurement apparatus on B mode to measure left ventricular end-diastolic dimension (LVDd) and posterior left ventricle wall thickness (PWT). As a substitute for the control group, we estimated predicted values for each subject based on their height to make a cross-sectional comparison with the actual measured values. RESULTS: A cross-sectional comparison of LVDd and PWT measured in junior high schoolers exhibited a significant increase between the 1st and 2nd grade (equivalent of American 7th and 8th grades, respectively) (p<0.01). A cross-sectional comparison of the predicted and actual LVDd values for each year of junior high school revealed a significant difference in 2nd year students (p<0.01). In contrast, there was a significant difference between predicted and actual PWT values in the 2nd and 3rd (equivalent of American 9th) grade students (p<0.05). In senior high schoolers, LVDd increased significantly between the 1st and 2nd grade as well as between the 2nd and 3rd grade, and PWT increased significantly between the 1st and 2nd grade (p<0.01). In senior high school, there was a significant difference between actual and predicted values of LVDd and PWT in all three grades (p<0.01). CONCLUSIONS: Continuous practice of rugby in junior and senior high school was associated with marked expansion of left ventricular volume and thickening of the left ventricular septum.