The aim of the present study was to investigate and compare the effect of physical training type on the structural and functional left ventricular changes in inactive male participants. For this object, forty inactive men voluntarily participated in the study and they were randomly divided to endurance (10), resistance (10), concurrent (10) and control (10) groups. The training program was conducted for eight weeks, three sessions per week. The endurance program included running with the intensity of 50% of heart rate reserve for 15 min in the first week, which increased to 80% of heart rate reserve for 30 min in the last week. The resistance program included circular resistance training with eight exercises in each session with the initial intensity of 50% one-repetition maximum, which increased to 85% one-repetition maximum. Concurrent endurance- resistance training group performed exactly resistance and endurance training programs groups alternatively for eigth weeks. Before and after the training periods, the considered variables were measured using one and two dimensional echocardiography. The research data were analyzed by the dependent t test for within-group evaluation and one-way Analysis of Variance (ANOVA) along with Bonferroni's post hoc test was used for between-group evaluation (α <0.05). Results: The findings showed that left ventricular end-diastolic volume and diameter in the concurrent and endurance groups significantly increased compared with those in the control and resistance groups (P<0.05). Also, there was significant difference in the left ventricular mass between concurrent and resistance groups, on the one hand, and endurance and control groups, on the other (P>0.05). Moreover, in the end-diastole, interventricular wall thickness and left ventricular posterior wall thickness in the resistance group significantly increased in comparison with those in the endurance and control groups (P<0.05). In the resistance group, end-systolic volume significantly decreased compared with the control and endurance groups (P<0.05). Nevertheless, no significant difference was observed between concurrent, resistance and endurance groups (P<0.05). Conclusion: It seems that doing endurance and resistance training at the same time in the current study led heart adaptation changes more toward the heart pattern of endurance athletes than that of strength athletes. This issue is caused by the adaptive effects of heart in response to endurance training which prevents from the excessive load, like high blood pressure, while doing resistance activities.
