---

Introduction: Exercises may alter the structure and function of the heart. Achieving the optimum performance of endurance activity depends creates compatibility in different body systems especially in the heart. The purpose of this study is to compare left ventricular structure of young taekwondo athletes’ men and non-athlete ones of Qazvin province.
Methods: In this descriptive-comparative study, 15 young and adult athletes are randomly selected and 15 non-athletes are selected by convenience sampling method. Echocardiograph machines Kontron with two-dimensional method, M- mode and Simpson measurement are used to investigate the left ventricular structure of the subject. Validity of Echocardiographic device is examined through a survey completed by cardiologist and reliability of the device is measured by the Pearson Correlation Coefficient P = 0.91. Data are analyzed using SPSS. 18.
Results: The indexes of LVPWD, LVPWS, IVSD, IVSS and LVM (P = 0.001) of left ventricular of athletes are significantly higher than the one of non-athletes. But in the variables of LVEDV (P = 0.022) and LVESV (P = 0.023) there is no significant difference within two group.
Conclusions: The thickness of the walls and left ventricular mass of taekwondo athletes increased but dimensions did not change. Hence, it is suggested that coaches practice aerobic exercises and increase cardio respiratory fitness and left ventricular capacity such as taekwondo through annual examination of athletes' heart structure.