It is unclear what the effect of long‐term, high‐volume soccer training has on left ventricular (LV) function during exercise in youth soccer players. This study evaluated changes in LV function during submaximal exercise in a group of highly trained male soccer players (SP) as they transitioned over a three‐year period from pre‐adolescent to adolescent athletes. Data were compared to age‐ and sex‐matched recreationally active controls (CON) over the same time period. Twenty‐two SP from two professional English Premier League youth soccer academies (age: 12.0 ± 0.3 years at start of the study) and 15 CON (age: 11.7 ± 0.3 years) were recruited. Two‐dimensional echocardiography was used to quantify LV function during exercise at the same submaximal metabolic load (approx. 45%VO2peak) across the 3 years. After controlling for growth and maturation, there were training‐induced changes and superiority (p < 0.001) in cardiac index (QIndex) from year 1 in the SP compared to CON. SP (year 1: 6.13 ± 0.76; year 2: 6.94 ± 1.31; and year 3: 7.20 ± 1.81 L/min/m2) compared to CON (year 1: 5.15 ± 1.12; year 2: 4.67 ± 1.04; and year 3: 5.49 ± 1.06 L/min/m2). Similar training‐induced increases were noted for mitral inflow velocity (E): SP (year 1: 129 ± 12; year 2: 143 ± 16; and year 3: 135 ± 18 cm/s) compared to CON (year 1: 113 ± 10; year 2: 111 ± 12; and year 3: 121 ± 9 cm/s). This study indicated that there was evidence of yearly, training‐induced increases in left ventricular function during submaximal exercise independent from the influence of growth and maturation in elite youth SP.