Dynamics of Change in Aerobic Capacity in 7-12 Year-Old Children Playing Soccer in Relation to Training Load

This study monitored changes in aerobic capacity in 7-12-year-old youth soccer players over three years, dividing them into two groups: Group 1 (ages 7-10) and Group 2 (ages 10-12). Key variables, maximum oxygen uptake (VO_2max) and the anaerobic threshold (AT), were measured using an incremental treadmill test. The data analysis revealed that training did not significantly influence aerobic capacity, with no strong correlation between training intensity and VO_2max, except between ages 7 and 8 (r-Pearson coefficient between -0.52 and 0.66). VO_2max differences between groups (Group 1: age 7, 46.2 ± 4.0; age 8, 59.1 ± 4.5; age 9, 63.4 ± 6.8; age 10, 59.5 ± 4.2 ml/kg/min; Group 2: age 10, 53.1 ± 8.5; age 11, 61.5 ± 5.1; age 12, 62.7 ± 5.7 ml/kg/min) appeared to be more related to individual developmental paths and genetics than to training or pubertal stages. There was no significant effect of training on the anaerobic threshold, indicating stability during submaximal efforts across the observed period. However, aerobic capacity improvements were noted, particularly in prolonged exercise duration and increased maximal aerobic speed (MAS), likely due to enhanced running efficiency and motor coordination. MAS for Group 1 increased from 8.7 km/h at age 7 to 9.5 km/h at age 10, while for Group 2, it rose from 8.5 km/h at age 10 to 9.2 km/h at age 12. This suggests significant potential for aerobic development during these early training years.